experiments surface tension

Surface Tension - Definition and Experiments

Understand Surface Tension in Physics

• Physics Laws, Concepts, and Principles
• Quantum Physics
• Important Physicists
• Thermodynamics
• Cosmology & Astrophysics
• Weather & Climate

Causes of Surface Tension

Examples of surface tension, anatomy of a soap bubble, pressure inside a soap bubble, pressure in a liquid drop, contact angle, capillarity, quarters in a full glass of water, floating needle, put out candle with a soap bubble, motorized paper fish.

• M.S., Mathematics Education, Indiana University
• B.A., Physics, Wabash College

Surface tension is a phenomenon in which the surface of a liquid, where the liquid is in contact with a gas, acts as a thin elastic sheet. This term is typically used only when the liquid surface is in contact with gas (such as the air). If the surface is between two liquids (such as water and oil), it is called "interface tension."

Various intermolecular forces, such as Van der Waals forces, draw the liquid particles together. Along the surface, the particles are pulled toward the rest of the liquid, as shown in the picture to the right.

Surface tension (denoted with the Greek variable gamma ) is defined as the ratio of the surface force F to the length d along which the force acts:

gamma = F / d

Units of Surface Tension

Surface tension is measured in SI units of N/m (newton per meter), although the more common unit is the cgs unit dyn/cm (dyne per centimeter).

In order to consider the thermodynamics of the situation, it is sometimes useful to consider it in terms of work per unit area. The SI unit, in that case, is the J/m 2 (joules per meter squared). The cgs unit is erg/cm 2 .

These forces bind the surface particles together. Though this binding is weak - it's pretty easy to break the surface of a liquid after all - it does manifest in many ways.

Drops of water. When using a water dropper, the water does not flow in a continuous stream, but rather in a series of drops. The shape of the drops is caused by the surface tension of the water. The only reason the drop of water isn't completely spherical is that the force of gravity pulling down on it. In the absence of gravity, the drop would minimize the surface area in order to minimize tension, which would result in a perfectly spherical shape.

Insects walking on water. Several insects are able to walk on water, such as the water strider. Their legs are formed to distribute their weight, causing the surface of the liquid to become depressed, minimizing the potential energy to create a balance of forces so that the strider can move across the surface of the water without breaking through the surface. This is similar in concept to wearing snowshoes to walk across deep snowdrifts without your feet sinking.

Needle (or paper clip) floating on water. Even though the density of these objects is greater than water, the surface tension along the depression is enough to counteract the force of gravity pulling down on the metal object. Click on the picture to the right, then click "Next," to view a force diagram of this situation or try out the Floating Needle trick for yourself.

When you blow a soap bubble, you are creating a pressurized bubble of air which is contained within a thin, elastic surface of liquid. Most liquids cannot maintain a stable surface tension to create a bubble, which is why soap is generally used in the process ... it stabilizes the surface tension through something called the Marangoni effect.

When the bubble is blown, the surface film tends to contract. This causes the pressure inside the bubble to increase. The size of the bubble stabilizes at a size where the gas inside the bubble won't contract any further, at least without popping the bubble.

In fact, there are two liquid-gas interfaces on a soap bubble - the one on the inside of the bubble and the one on the outside of the bubble. In between the two surfaces is a thin film of liquid.

The spherical shape of a soap bubble is caused by the minimization of the surface area - for a given volume, a sphere is always the form which has the least surface area.

To consider the pressure inside the soap bubble, we consider the radius R of the bubble and also the surface tension, gamma , of the liquid (soap in this case - about 25 dyn/cm).

We begin by assuming no external pressure (which is, of course, not true, but we'll take care of that in a bit). You then consider a cross-section through the center of the bubble.

Along this cross section, ignoring the very slight difference in inner and outer radius, we know the circumference will be 2 pi R . Each inner and outer surface will have a pressure of gamma along the entire length, so the total. The total force from the surface tension (from both the inner and outer film) is, therefore, 2 gamma (2 pi R ).

Inside the bubble, however, we have a pressure p which is acting over the entire cross-section pi R 2 , resulting in a total force of p ( pi R 2 ).

Since the bubble is stable, the sum of these forces must be zero so we get:

2 gamma (2 pi R ) = p ( pi R 2 ) or p = 4 gamma / R

Obviously, this was a simplified analysis where the pressure outside the bubble was 0, but this is easily expanded to obtain the difference between the interior pressure p and the exterior pressure p e :

p - p e = 4 gamma / R

Analyzing a drop of liquid, as opposed to a soap bubble , is simpler. Instead of two surfaces, there is only the exterior surface to consider, so a factor of 2 drops out of the earlier equation (remember where we doubled the surface tension to account for two surfaces?) to yield:

p - p e = 2 gamma / R

Surface tension occurs during a gas-liquid interface, but if that interface comes in contact with a solid surface - such as the walls of a container - the interface usually curves up or down near that surface. Such a concave or convex surface shape is known as a meniscus

The contact angle, theta , is determined as shown in the picture to the right.

The contact angle can be used to determine a relationship between the liquid-solid surface tension and the liquid-gas surface tension, as follows:

gamma ls = - gamma lg cos theta

• gamma ls is the liquid-solid surface tension
• gamma lg is the liquid-gas surface tension
• theta is the contact angle

One thing to consider in this equation is that in cases where the meniscus is convex (i.e. the contact angle is greater than 90 degrees), the cosine component of this equation will be negative which means that the liquid-solid surface tension will be positive.

If, on the other hand, the meniscus is concave (i.e. dips down, so the contact angle is less than 90 degrees), then the cos theta term is positive, in which case the relationship would result in a negative liquid-solid surface tension!

What this means, essentially, is that the liquid is adhering to the walls of the container and is working to maximize the area in contact with solid surface, so as to minimize the overall potential energy.

Another effect related to water in vertical tubes is the property of capillarity, in which the surface of liquid becomes elevated or depressed within the tube in relation to the surrounding liquid. This, too, is related to the contact angle observed.

If you have a liquid in a container, and place a narrow tube (or capillary ) of radius r into the container, the vertical displacement y that will take place within the capillary is given by the following equation:

y = (2 gamma lg cos theta ) / ( dgr )

• y is the vertical displacement (up if positive, down if negative)
• d is the density of the liquid
• g is the acceleration of gravity
• r is the radius of the capillary

NOTE: Once again, if theta is greater than 90 degrees (a convex meniscus), resulting in a negative liquid-solid surface tension, the liquid level will go down compared to the surrounding level, as opposed to rising in relation to it.

Capillarity manifests in many ways in the everyday world. Paper towels absorb through capillarity. When burning a candle, the melted wax rises up the wick due to capillarity. In biology, though blood is pumped throughout the body, it is this process which distributes blood in the smallest blood vessels which are called, appropriately, capillaries .

Needed materials:

• 10 to 12 Quarters
• glass full of water

Slowly, and with a steady hand, bring the quarters one at a time to the center of the glass. Place the narrow edge of the quarter in the water and let go. (This minimizes disruption to the surface, and avoids forming unnecessary waves that can cause overflow.)

As you continue with more quarters, you will be astonished how convex the water becomes on top of the glass without overflowing!

Possible Variant: Perform this experiment with identical glasses, but use different types of coins in each glass. Use the results of how many can go in to determine a ratio of the volumes of different coins.

• fork (variant 1)
• piece of tissue paper (variant 2)
• sewing needle

Place the needle on the fork, gently lowering it into the glass of water. Carefully pull the fork out, and it is possible to leave the needle floating on the surface of the water.

This trick requires a real steady hand and some practice, because you must remove the fork in such a way that portions of the needle do not get wet ... or the needle will sink. You can rub the needle between your fingers beforehand to "oil" it increase your success chances.

Variant 2 Trick

Place the sewing needle on a small piece of tissue paper (large enough to hold the needle). The needle is placed on the tissue paper. The tissue paper will become soaked with water and sink to the bottom of the glass, leaving the needle floating on the surface.

• lit candle ( NOTE: Do not play with matches without parental approval and supervision!)
• detergent or soap-bubble solution

Place your thumb over the small end of the funnel. Carefully bring it toward the candle. Remove your thumb, and the surface tension of the soap bubble will cause it to contract, forcing air out through the funnel. The air forced out by the bubble should be enough to put out the candle.

For a somewhat related experiment, see the Rocket Balloon.

• piece of paper
• vegetable oil or liquid dishwasher detergent
• a large bowl or loaf cake pan full of water

Once you have your Paper Fish pattern cut out, place it on the water container so it floats on the surface. Put a drop of the oil or detergent in the hole in the middle of the fish.

The detergent or oil will cause the surface tension in that hole to drop. This will cause the fish to propel forward, leaving a trail of the oil as it moves across the water, not stopping until the oil has lowered the surface tension of the entire bowl.

The table below demonstrates values of surface tension obtained for different liquids at various temperatures.

Experimental Surface Tension Values

Edited by Anne Marie Helmenstine, Ph.D.

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Detergents, soaps and surface tension

In association with Nuffield Foundation

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Various experiments to observe the effects of detergents and soaps on the surface tension of purified and hard water

A fine insoluble powder, such as talcum powder, is sprinkled on a clean water surface in a beaker, a drop of detergent or soap solution added to the centre, and the effect observed as the surface tension of the water is changed. This can be repeated with other powders after cleaning the beaker and using fresh water samples. A needle can be carefully floated on a clean water surface and the effect of adding detergent or soap observed. Finally the same experiments can be repeated using samples of hard water to compare the effects.

This is a series of quick, simple, class experiments which can be extended or shortened as desired. Each experiment should take no more than two minutes, though the cleaning of the beaker between experiments may take up more time than expected. If a full range of experiments is desired, the time taken could amount to 30 minutes, but this may not be justified in terms of the learning objectives concerned.

• Beaker (250 cm 3 )
• Glass stirring rod
• Clean sewing needle (note 1)

Apparatus notes

• The sewing needle should be a fine needle, and for safety issued to students with the pointed end inserted into a piece of card bearing a safety warning about handling the needle.
• Talcum powder, in pepper pot or similar dispenser
• Other powders (see technical notes)
• Liquid detergent in a dropping bottle
• Liquid soap in a dropping bottle
• Access to a supply of purified water (distilled or deionised), about 1 dm 3  per working group
• Access to a supply of hard water

Health, safety and technical notes

• Read our standard health and safety guidance
• Other powders – Any powders used other than talcum powder, such as lycopodium powder or carbon powder, should be subject to a risk assessment. Lycopodium powder is a potential allergen.
• Liquid detergent – Any washing-up liquid or multipurpose detergent will suffice.
• Liquid soap - Genuine liquid soap or soap flakes from which the liquid can be made, is increasingly difficult to obtain. Wanklyn’s and Clarke’s soap solutions should still be available from chemical suppliers. Lux soap flakes are ideal for making liquid soap if you can source them. Granny’s Original and other non-branded soap flakes work fine but need to be used in solution as soon as they are made. They do not form a stable emulsion and precipitate out overnight. Note that most liquid hand washes are based on the same detergents as washing-up liquids and do not contain soap. To obtain soap solution from soap flakes – dissolve soap flakes (or shavings from a bar of soap) in ethanol – use IDA (Industrial Denatured Alcohol) (HIGHTLY FLAMMABLE, HARMFUL) – see CLEAPSS Hazcard HC040a and CLEAPSS Recipe Book RB000. Do not dilute with water.
• Hard water – A supply of hard water can be made by stirring solid calcium sulfate into a large volume of tap water, allowing to stand for some time then, after the undissolved solid has settled out, decanting the clear solution into a container suitable for students to collect their samples as required. Label as ‘Hard Water’. Allow about 1 dm 3  for each working group in the class.
• Half fill the beaker with purified water.
• Sprinkle the water surface carefully with a fine layer of powder.
• Add one drop only of detergent in the middle of the water surface. Observe what happens. Does the talcum powder stay on the surface, or does it sink?
• Clean the beaker thoroughly, half-fill again with purified water, and repeat steps two and three using a drop of liquid soap instead of detergent. Compare what happens to what happened in the previous experiment.
• Repeat steps three   and four, only this time use hard water instead of purified water. Are the results different from those obtained with purified water? If so, in what ways?
• Other powders may be available to test instead of talcum powder, to see whether the type of powder makes any difference. If you do test any of these, what differences do you find?
• Again using a clean beaker with purified water, try to float a fine sewing needle on the surface by carefully lowering it into the beaker, avoiding breaking the surface with your fingers, and dropping it from as close above the surface as possible. Once you have a needle floating, add a small drop of detergent to the water, but away from the needle. What happens?

Teaching notes

This series of brief experiments on the surface tension of water, and the effects of detergents and soaps on this, can serve as an introduction to the phenomenon of surface tension, with a discussion of results leading into simple theory. Alternatively, it could be used to illustrate prior teaching of the topic, leading to discussion of what is happening when detergents and soaps are added, including the differences found with hard water.

A diagram of the forces between water molecules at the surface and centre of a liquid.

There is a net force of attraction between the molecules of water (or any other liquid) holding the molecules together. For a molecule in the middle of the liquid, these forces, acting equally in all directions, more or less balancing out. For a molecule in the surface layer of the liquid, the forces do not balance out, and all the molecules in the surface layer are pulled towards each other and towards the bulk of the liquid. This brings these molecules closer to their neighbours until increasing forces of repulsion create a new balance, and gives rise to the phenomenon of surface tension.

When an object falls onto the surface, it has to push the water molecules apart. If the effect of the weight of the object is insufficient to match the attractive forces between molecules in the surface layer, the object will not enter the surface. Careful observation of the floating needle will show that the water surface is bent down under the weight of the needle, the surface tension causing it to behave as if the needle was supported by a flexible skin.

A diagram of the forces enabling a needle to float on water

Molecules of most detergents and soaps are long chain hydrocarbon molecules with an ionic group at one end, usually carrying a negative charge, thus making it an anion. This charge is balanced by the opposite charge of a soluble cation, for example Na + . The long hydrocarbon chains do not interact well with water molecules, and many of them are effectively ‘squeezed out’ to the interfaces between the water and the air or the glass sides of the beaker. The effect of these molecules on the water surface is to considerably weaken the forces between water molecules there, thus lowering the surface tension.

A diagram of a detergent or soap molecule, which is responsible for breaking down surface tension

When the drop of detergent is added to the powdered surface, the initial effect is to draw the powder back to the edges very rapidly as the detergent molecules form their own surface layer with a lower surface tension than the water. As the detergent gradually mixes with the water, the powder begins to sink, and a needle will now pass through the surface with ease under its own weight. However, if lycopodium powder is used, which is less dense than water, it remains at the edges. Other powders may clump into nodules if they are not wetted by the detergent solution.

A diagram showing detergent molecules in a beaker of water, some lining the surfaces and other forming clumps

In hard water there is a significant concentration of calcium, Ca 2+ , and/or magnesium, Mg 2+ , cations. These cations form an insoluble compound with soap anions, so instead of forming a surface layer, they are precipitated out, leaving the surface tension largely unchanged.

2COO − (aq) + Ca 2+ (aq) → (COO) 2 Ca(s)

However, the calcium and magnesium salts of many detergent molecules are soluble, so detergents lower the surface tension of hard water.

Additional information

This is a resource from the  Practical Chemistry project , developed by the Nuffield Foundation and the Royal Society of Chemistry. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures. Practical Chemistry activities accompany  Practical Physics  and  Practical Biology . 

© Nuffield Foundation and the Royal Society of Chemistry

• 14-16 years
• Practical experiments
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Science Projects > Physics & Engineering Projects > Water Experiments  

Water Experiments

Surface tension experiments.

Surface tension is one of the most important properties of water .

It is the reason that water collects in drops, but it’s also why plant stems can “ drink water ,” and cells can receive water through the smallest blood vessels.

You can test multiple surface tension experiments using just a few household items.

What You Do:

1. Start with a cup of water and some paperclips. Do you think a paperclip will float in the water? Drop one in the cup to find out. Since the paperclip is denser than the water, it will sink to the bottom of the cup.

Now find out if you can use surface tension to float the paperclip. Instead of dropping the paperclip into the cup, gently lay it flat on the surface of the water.

(This is tricky — it may help to place a piece of paper towel slightly bigger than the paperclip in the water. Then lay the paperclip on top of it. In a minute or so, the paper towel will sink, leaving the paperclip floating on top of the water.)

2. Even though the paperclip is still denser than the water, the strong attraction between the water molecules on the surface forms a type of ‘skin’ that supports the clip.

3. Now put a drop of dish soap in the water. This will bind with the water molecules, interfering with the surface tension .

The paper clip will sink. You can try floating other things on top of the water also – pepper floats well until you add dish soap. Can you find any other light items that will float?

Surface tension creates the ‘skin’ on top of the water, but it is also what causes water to stick together in drops.

Observe how these drops stick together by experimenting with water and a penny. All you need is a cup of water, a penny, and a medicine dropper .

First make a prediction: how many drops of water do you think you can fit on the top surface of the penny? Add one drop. After seeing how much room it takes, do you want to rethink your first prediction?

Now continue carefully adding drops until the water spills off the penny. Try this three times, recording the number of drops each time, and then find the average number of drops that can fit.

Surface tension is the reason you can fit so much water on the penny. The water molecules attract each other, pulling together so the water doesn’t spill.

Try this experiment with different-sized coins. Predict how many drops you can fit on a quarter compared with the penny.

For one final surface tension experiment, start with a full glass of water. Predict how many pennies you can add to the water without the glass overflowing. Gently add pennies one by one. Because of surface tension, the water will rise above the rim of the glass before it spills! Compare your original prediction with the number of pennies you were able to add.

Freezing Point

Have you ever wondered why rivers and lakes freeze in the winter, but oceans do not? In this experiment we will see that it is the presence of salt in the ocean that makes it less likely to freeze.

What You Need:

• 1-gallon freezer bag
• 1-quart freezer bag
• crushed ice
• thermometer

1. Fill the gallon freezer bag half full with crushed ice. Add one cup of salt and seal the bag. Put on some gloves and knead the ice and salt until the ice has completely melted.

2. Use the thermometer to record the temperature of the saltwater mixture. Even though the ice has melted, the temperature should be less than 32°F (0°C).

3. Now put about an ounce of water in the quart freezer bag. Seal the quart bag and then put it in the saltwater mixture in the larger bag. Seal the larger bag also and leave it until the water inside the quart bag freezes.

How did the water freeze when surrounded only by saltwater?

The salt broke apart the bonds between the water molecules in the ice, causing it to melt, but the temperature remained below the freezing point for pure water.

Salt (and other substances dissolved in water) will always lower the freezing point .

This is why water in the ocean rarely freezes.

• Find out more about salt water by making a Solar Purifier

More Water Projects:

•   Liquid Density
•   Hot Water: Convection Science
•  Water Wheel

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Surface Tension Experiments

Science can be absolutely hands-on and engaging for kids. Learn about the surface tension of water with our simple definition below. Plus, check out these fun surface tension experiments to try at home or in the classroom. As always, you’ll find fantastic and easy to do science experiments at the tip of your fingers.

What Is Surface Tension Of Water?

Surface tension exists on the surface of water because water molecules like to stick to each other. This force is so strong that it can help things sit on top of the water instead of sinking into it. Like our pepper and soap experiment below.

It is the high surface tension of water that allows a paper clip, with much higher density, to float on water. It also causes drops of rain to stick to your windows, and is why bubbles are round. Surface tension of water also helps propels water-striding insects on the surface of ponds.

Also learn about capillary action !

Scientist, Agnes Pockels discovered the science of surface tension of fluids simply doing the dishes in her own kitchen.

Despite her lack of formal training, Pockels was able to measure the surface tension of water by designing an apparatus known as the Pockels trough. This was a key instrument in the new discipline of surface science. In 1891, Pockels published her first paper, “Surface Tension,” on her measurements in the journal Nature.

Easy Surface Tension Experiments

Here are some fun ways to demonstrate the surface tension of water. Plus, all you need is a handful of common household supplies. Let’s play with science today!

Bubble Snakes

Find out how you can blow up a gigantic bubble snake all with the help of surface tension.

Drops Of Water On A Penny

A fun science activity with pennies and water. How many drops of water do you think you can get on a penny? The results might surprise you and all because of surface tension!

Floating Paperclip Experiment

How do you make a paperclip float on water? Learn about surface tension of water, with a few simple supplies.

Magic Pepper and Soap Experiment

Sprinkle some pepper in water and make it dance across the surface. Learn about the surface tension of water when you try this fun pepper and soap experiment with kids.

Magic Milk Experiment

Try this color-changing milk and soap experiment. Similar to water, the dish soap breaks the surface tension of the milk, allowing the food coloring to spread out.

Geometric Bubbles

Explore surface tension while you blow bubbles! Make your own homemade bubble solution too!

Paper Clips In A Glass

How many paper clips fit in a glass of water? It’s all to do with surface tension!

Skittles Experiment

Why don’t the skittles colors mix in water? Explore how surface tension of water makes effects the process. Also set this up with M&Ms.

Soap Powered Boat Experiment

Explore surface tension up close as kids observe firsthand how soap influences the movement of a small boat on the water’s surface.

Bonus Activity: Water Drop Painting

Not an experiment as such but still a fun activity that combines science and art. Paint with water drops using the principle of surface tension of water.

Free Printable Science Project Worksheets!

What is the scientific method?

The scientific method is a process or method of research. A problem is identified, information about the problem is gathered, a hypothesis or question is formulated from the information, and the hypothesis is put to test with an experiment to prove or disprove its validity. Sounds heavy…

What in the world does that mean?!? The scientific method should simply be used as a guide to help lead the process.

You don’t need to try and solve the world’s biggest science questions! The scientific method is all about studying and learning things right around you.

As kids develop practices that involve creating, gathering data evaluating, analyzing, and communicating, they can apply these critical thinking skills to any situation. To learn more about the scientific method and how to use it, click here.

Even though the scientific method feels like it is just for big kids…

This method can be used with kids of all ages! Have a casual conversation with younger kiddos or do a more formal notebook entry with older kiddos! Learn more about using the scientific method with kids.

Helpful Science Resources To Get You Started

Here are a few resources that will help you introduce science more effectively to your kiddos or students and feel confident yourself when presenting materials. You’ll find helpful free printables throughout.

• Best Science Practices (as it relates to the scientific method)
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Surface Tension In Water Explanation and Experiment

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What is Surface Tension in Water?

To understand surface tension in water, we need to look at the structure of water.

A water molecule is made up of two hydrogen atoms and one oxygen atom. There are two ends to a water molecule. The two positively charged hydrogen atoms at one end and the negatively charged oxygen atom at the other end give the water molecules two poles.

Molecules that are polar will mix with each other. This is called cohesion. This happens in water because the negative charge of the oxygen atom in a water molecule is attracted to the positive charge of the hydrogen atoms in another water molecule.

Cohesion simply means that water molecules like to stick to each other. This is caused by the slightly negative charge of the oxygen atom of one water molecule being attracted to the slightly positive charge of the hydrogen atoms of another water molecule.

When the water molecules stick together they form a “skin”. This skin is strong enough to hold some insects, like water striders, on top of the surface of the water.

Let’s observe surface tension in water with the following activity.

Surface Tension in Water Experiment

• 1 small bowl of water. Fill about 3/4 full of water
• 1 Sheet of paper towel.
• 1 Small paper clip

Instructions

• Drop the paper clip directly into the water. What happens?
• Thoroughly dry the paper clip.

• Put the paper clip in the center of the folded paper towel.
• Slowly and gently lower the paper towel into the water and wait as it absorbs the water. The paper towel will begin to drop into the water.
• Slowly remove the paper towel up one side of the bowl, and be careful not to touch the paper clip.

What Happened In Our Surface Tension in Water Experiment?

Water molecules are polar. This means they have a positive end and a negative end. (You can read more about surface tensions of water, water molecules, and polarity by reading this post on testing the properties of water.

The negative ends stick to the positive ends, and the positive ends stick to the negative ends. This creates a “skin”; we call this surface tension.

When the paper clip was dropped into the water, the “skin” on the water wasn’t strong enough to hold the weight and force of the paper clip.

When the paper towel was used, the weight of the paper clip was evenly distributed on the surface of the water as the paper towel absorbed water and began to sink.

Read about surface tension and have your children make their own water strider insect that floats on the surface of the water.

For a more in-depth look at the properties of water, check out our Testing The Properties Of Water post and activities!

MORE WATER EXPERIMENTS

Water Quality Experiment

Charcoal Water Purifying Experiment

Learn About The Water Cycle (and an experiment)

I hold a master’s degree in child development and early education and am working on a post-baccalaureate in biology. I spent 15 years working for a biotechnology company developing IT systems in DNA testing laboratories across the US. I taught K4 in a private school, homeschooled my children, and have taught on the mission field in southern Asia. For 4 years, I served on our state’s FIRST Lego League tournament Board and served as the Judging Director.  I own thehomeschoolscientist and also write a regular science column for Homeschooling Today Magazine. You’ll also find my writings on the CTCMath blog. Through this site, I have authored over 50 math and science resources.

Water Surface Tension Experiment

Experiment to teach kids about water surface tension.

Posted by Admin / in Matter Experiments

Water has a property we see everyday, but may not know it is there until it is pointed out. It is called water surface tension. If you have ever watched bugs appear to skate on top the surface of the water, they are using water surface tension to move across the water without sinking. Try this surface tension experiment to help to understand why.

Materials Needed

• Small paperclip, Size # 1 (about 1.25" long (3.2 cm))
• Small bowl or cup
• Liquid soap
• Mixing spoon, if needed

WATER TENSION EXPERIMENT STEPS

Step 1: Fill up a cup or bowl of water. Plain tap water works great.

Step 2: Take some metal paperclips and drop them into the bottom of the water to demonstrate how metal paperclips have a density greater than water so they sink.

Show how metal paperclips sink in water

Step 3: Carefully place a metal paperclip on the surface of the water. Use a #1 paperclip (they work the best).

Carefully place the paperclip on the water surface

Step 4: Show the kids how the paperclip now magically floats on the surface of the water.

Step 5: Shake the cup/bowl of water to show that the paperclip is the same as the others and let them see it sinks.

Step 6: Make another paperclip float on the water surface.

Step 7: Now add some liquid soap to the water where the paperclip is floating. What happened?

Step 8 (optional): Try to repeat the experiment using liquids other than water. Do you get the same results?

SCIENCE LEARNED

Water has cohesion that pulls the water molecules together. We can see examples of water cohesion in nature. Water droplets form to make rain. If you pour water over a car windshield it groups together to form drops and streams of water. Water joins together to form streams, rivers and oceans. Water in soil helps that soil stick together so if you dig a hole, it stands up for a while. If soil did not have cohesion then everytime the wind blew hard, it would result in dust storm. Without the cohesive forces of water our world would be much different.

In the experiment we start with showing the kids that paperclips are heavier than water and they sink right to the bottom. When they are carefully placed at the water surface, however, the paperclips float. There is an added force at the surface of the water that is not present under the surface of the water. It is called surface tension. The surface tension is in fact the cohesion of the water pulling it together. Since all of the water is below the surface and their is no water above it there is internal pressure created in the water at the surface. This acts like a skin that helps the paperclip float on the water surface.

What happened when the soap was added? Why did the paperclip suddenly sink? Simple. The soap reduce the cohesion force in the water, resulting removing the "skin" from the water surface.

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Air Pressure Experiment

in Matter Experiments

Simple Experiment with a good visual demonstration of changing air pressure.

Hot and Cold Water Density

Use this simple experiment to demonstrate hot and cold water density..

Water Cycle Experiment

Experiment to show all the phases of the water cycle.

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Easy Science: Surface Tension Water Drop Races

Science experiments don't need to be complicated! A water drop race is a simple science project is a great was to pass the time when you need a quick distraction for your kids. It can be part of an in-depth classroom exploration into the concept of surface tension and molecule cohesion.

What is Surface Tension?

Surface tension is

the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules. The cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension. The molecules at the surface of a glass of water do not have other water molecules on all sides of them and consequently they cohere more strongly to those directly associated with them. USGA

A classic kids surface tension experiment is the one where you drip water drop by drop onto a penny. You can also observe surface tension by floating a paper clip on the surface of water.

Bugs also use surface tension to hang out on ponds and streams. Leaves during a rain storm also demonstrate water's cohesive nature.

For this water drop race experiment, surface tension is responsible for the spherical shape of the water droplets. The waxy paper keeps the water from being absorbed away by the surface they sit on.

However, even if your child is too young to grasp the concepts of surface tension and the bonding properties of water molecules, it's still a super fun indoor activity that will make kids say, "Cool!!!"

Water Drop Surface Tension Experiment

How to conduct water drop races

You will need: one straw per scientist glass of water water dropper wax paper or parchment paper

Observations

Kids will start to notice ways in which they can control their water drops. Young scientists can explore surface tension strength by blowing air through the straw extra hard, which will cause larger water drops break up into smaller water beads.

Kids will also learn how to blow water beads together to merge them into larger droplets. No doubt, they will have fun sucking water drops up the straw and blowing them back out! My kid loved blowing his off the table to "plop" on the floor! ( It's just water, after all. )

Conclusions

Whether or not you use this surface tension experiment to go into depth about how water molecules, tension and cohesion work, water drop races provide lots of entertainment!

I absolutely loved how this project has the added bonus of keeping the kids busy for an extended period of time without a lot parental involvement. And because it's just a small amount of water that is used, you won't have to worry about everything getting wet or the kids making a big mess to clean up!

More water experiments

• Water refraction is just like magic!
• Amaze your kids with a leak proof hole in a bag!
• Make a coin jump off a bottle
• All our favorite indoor water activities

I First Published this idea 3/16/09.

Reader Interactions

Leptir says

June 04, 2010 at 9:14 am

Looks like fun 🙂 I'll probably try it in my classroom with kids. Thanks for sharing 🙂

MaryAnne says

June 04, 2010 at 12:15 pm

What an excellent activity! Thanks for the idea =)

June 05, 2010 at 1:44 am

Christy says

June 05, 2010 at 5:33 pm

My kids will love this! Thanks.

Raising a Happy Child says

June 09, 2010 at 11:14 am

I have to try it out - wind races have been popular here, but we haven't done them with water.

September 12, 2016 at 5:29 pm

Hi! I'm about to launch a year-long science course for young kids at some of the local schools. I love this idea! It will be a PERFECT fun activity to end the "Surface tension" lesson with! We'll be doing some fun experiments to bring the concept home to the kids, and this is just what I needed! Thanks so much Erica!

September 14, 2016 at 12:16 pm

Glad the idea was useful!

Julie C Billow says

April 17, 2017 at 12:45 am

I just tried this out myself and had fun! Try adding some color to the experiment by drawing on the waxed paper with markers and then watch as the water drops blow through the colors and absorb them. Fascinating!

April 19, 2017 at 11:07 am

I love that idea!

March 09, 2018 at 3:22 pm

Used this today with my preschool kids. Many had fun watching the water break apart and go back together. I added food coloring to the water and used freezer paper ??

Rebecca says

March 28, 2019 at 3:00 pm

We used color waters and blew the the color water droplets into each other to see what colors they turned into. The kids loved it.

March 29, 2019 at 8:08 am

What a fantastic idea!

Racing Lolly Sticks – Surface Tension Experiment

June 26, 2013 By Emma Vanstone 7 Comments

How do you make a lolly stick race across water? Would you believe me if I told you all you needed was a drop of washing-up liquid ( dish soap ) and some water to do a fun surface tension experiment ?

Racing lolly sticks – surface tension experiment

You’ll need.

A large container – we used our water table, but a bath would work too.

Washing up liquid – dish soap

Wooden lolly stick

Instructions

Fill your container with water. You only need it a couple of cm deep.

Place the lolly stick on the water. It should float.

Add a little washing-up liquid at one end of the stick. It should zoom off.

Why does this work?

This simple science investigation is a great demonstration of surface tension . When you have a container full of water, the water molecules below the surface are pulled together equally in all directions, but those on top are pulled together more tightly, as they don’t have water molecules above them. This draws them together to form a kind of ‘skin’ that we call surface tension. It is the surface tension that stops the lolly stick from sinking. When washing-up liquid is dropped onto the surface of the water it disrupts the arrangement of the water molecules, decreasing the surface tension behind the stick.

Water molecules move from areas of low surface tension to high surface tension, and so the lollystick stick moves.

More surface tension investigations

Make a small boat and investigate to see whether disrupting the surface tension of the water makes it move.

Ask a friend to blow waves over the surface of the water with a straw, investigate whether the surfboard still moves when washing up liquid is added.

Set up a lollystick race for multiple children!

Another way to demonstrate surface tension is to disrupt cocktail sticks in a bowl of water or to make a hole in a layer of pepper on water !

More Science for Kids

If you enjoyed this experiment, we’ve got lots more science for kids you’ll love.

Try our STEM Challenges , fun experiments for science at home or science fair ideas .

Last Updated on September 8, 2023 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

June 28, 2013 at 2:23 pm

This is a great summer science activity!

July 04, 2013 at 4:19 pm

What a neat and fun lesson!! Thank you for sharing at Sharing Saturday!!

July 20, 2013 at 8:36 pm

Oh I never knew that. I’ve been collecting lollipop sticks and I’m sure my boys will love this activity.

March 28, 2014 at 10:19 am

October 08, 2015 at 6:13 pm

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Floating Paper Clip on Water – Science Experiment

• March 10, 2021
• 10 Minute Science , 7-9 Year Olds , Physics

Today, I am going to share an awesome science concept ‘Surface Tension’ through a classic science experiment.

If you are in need of science project for your science fair day, then here is the best science activity you can pick to perform on the day.

How to Make Paper Clips Float on Water

Objective: To explore the strength of water molecules and investigate the science concept ‘Surface Tension’.

Materials Required:

All the materials you are going to collect on your experiment table in this activity are easily available. Here is the simple supplies list:

1) Paper Clips

2) A transparent glass Bowl

3) Clean Water

4) Tissue Paper

5) A New Pencil attached with Eraser or Craft Stick

Instructions to do Floating Paper Clip Science Experiment

Complete Step By Step Video

Take a clean and transparent glass bowl on your experiment table and fill it with fresh water.

Make sure to fill the glass bowl with water nearer to the top or brim of the bowl. Such that we are making things go easily during the activity.

Also, you need to wash your hands before the experiment but only using water.

Do not use soap when you decide to conduct this activity because soap may tamper the outcome results as it holds its own surface tension properties.

Just to show your children, perform a small step how a paper clip actually does when dropped in water.

So, take a paper clip and simply drop it in to the glass bowl filled with water. And now ask your child to check whether it is sinking or floating in the bowl of water.

Absolutely, the paper clip sinks to the bottom of the bowl because of density differences.

Remove the paper clip out of the bowl to perform the next step. Then, take a tissue paper and cut it in the shape of square. Make sure the size of the cut tissue paper is slightly larger than the paper clip.

Now, gently place the square cut tissue paper into the glass bowl with water. You will observe the tissue paper start floating and reaches to top of the water.

At this point of time, place our paper clip carefully on top of the tissue paper. This is a bit tricky step as there is no balance inside water to hold things in right place.

Hope this helps you to place the experiment clip in right place on tissue paper and does not touch the water surface.

It is time to poke tissue paper and this is the favourite step for children.

Hahaha! Take the pencil with eraser on the other side. Use the eraser side to poke the tissue paper.

But make sure you are not touching the paper clip on the tissue paper while poking it with pencil. You need to poke the tissue paper until it reaches to the bottom.

Here is another trick. Extend a paperclip to create a holder like this.

Now carefully place the paper clip on the holder and dip it slowly in the water. Viola.. your paper clip will float now.

I let my kids to float as many paper clips as possible on the surface of the water.

We even had fun blowing air through straw to make the paperclips move in circular motion while floating on the water.

What you observe here? You will observe the tissue paper sinks but not the paper clip. The paper clip remains on the surface of the water floating. It looks magical but it is not a magic, it is actually the science. Let us learn the science behind this super classic experiment.

Science involved in Floating Paper Clip Science Experiment

Why does paper clips sinks to bottom in water? Generally, paper clips are of metal material and normally sink to bottom when put in water.

Because the metal materials are usually heavy in weight and possess higher density when compared to water. That is the reason, paper clips usually sink to the bottom in water.

However, we can make the paper clips to float on the surface area of water using simple science trick.

The floating paper clip science experiment is all about ‘ Surface Tension ’. Surface tension is the cohesive nature of liquid surface film due to the attraction between the molecules which tends to the minimum surface area possible.

In this floating paper clip activity, water molecules hold tightly and stay together because of surface tension.

And we are creating “skin” on the water surface which holds water molecules tightly and suspending the paper clip to appear as floating.

Until the water molecules stay together and hold tightly, they can support paper clip to float on water surface.

So, we are creating ideal and right conditions to support the paper clip to float using tissue paper.

Using tissue paper, we are suspending the paper clip on the surface tension of the water and slowly removing the tissue under it.

Actually, the paper clip does not float but it holds up by the cohesive forces of surface tension and appear as floating.

The same science is being used by the tiny insects to walk across the water surface of the lakes.

Extension Experiment

Here is another awesome experiment that proves surface tension in an educational way. This is an extension activity to floating paper clip science experiment.

Set up the experiment table with a bowl of water. Repeat the same steps of the above activity and make a paper clip float.

Now, dip your finger in a little amount of dish soap and put it on the surface of the water. You will notice the floating paper clip drop to the bottom that means the paper clip sinks to the bottom of the bowl.

Because the soap liquid spreads or pushes away the surface or skin of the water surface to its sides as soon as the soap comes in contact with water.

The soap liquid has a thin layer of surface tension which is less dense than the water surface tension.

That is the reason the soap layer does not hold paper clip anymore and makes it sink.

If you even want to take the experiment further, you can try the same experiment using other steel objects instead of paper clips.

Also, you can replace water with different varieties of juices, milk, etc. and check whether the outcome results are same.  

You can try these interesting and related science experiments with water and surface tension:

Learn to Make a Square Bubble

DIY Soap Powered Boats

Walking Water Experiment

Swirling Magic Milk Experiment

Floating Drawings on Water

Chemical Formula of Surface Tension and Water

Surface tension is the nature of liquid molecules to get attracted due to cohesive forces and remain tightly and tends to minimal surface area possible. The chemical formula of surface tension is:

r = 1/2 . F/L

r is surface tension

F represents Force

L represents Length

Water is the major constituent of Earth’s atmosphere with chemical formula, H2O. In chemical formula , H represents hydrogen atoms and 2 says hydrogen atoms in two numbers. Whereas O represents one oxygen atom. Hydrogen atoms are positively charged and oxygen atom is negatively charged. That means, water molecule is a constituent of two hydrogen atoms and one oxygen atom. Water is colorless, tasteless, odorless, and offers no calories.

Water molecule is stable when two positively charged hydrogen atoms bond to one negatively charged atom. There is a slight difference in charges while bonding which is known as dipole. The bond between two water molecules is referred as hydrogen bonding. The water molecules on the surface of water in the bowl attract each other due to cohesive forces and form surface tension on top of it. This surface tension is the reason to hold paper clip on top of water.

When you dip the soap liquid in the water, the surface tension breaks because the thin layer of soap liquid reduces the water surface tension because of existence of non-polar and dipole free bodies. Hence, it is difficult for paper clips to float and sinks to bottom.

Questions to discuss during the Experiment

Asking questions during the experiment helps children to improve their critical thinking skills and encourages them to do wonders in science. Here are a few questions to discuss about the experiment:

1) Why does paper clip floats on water but not on other liquids?

2) Are there any other liquids that hold paper clip to float?

3) What do you think the shape of the paper clip impacts the floating ability?

4) How many paper clips can the water surface tension holds?

5) Is it possible to increase the surface tension of the water naturally?

6) What are the other liquids that show stronger surface tension and good at floating things?

Yes, absolutely you can float a paper clip on water. Paper clips are of steel material which defy the floating physical laws. But surprisingly we can float steel paper clips on the water using surface tension created on top surface area of water. The higher surface tension of water molecules holds the paper clips float on water.

Naturally, paper clips are of heavy weight and sinks in the water container as it shows greater density than water. But when you suspend the paper clip carefully on top of the water surface, it floats amazingly. This is because of surface tension formed due to the cohesive forces between the water molecules. You can find many tricks to make the paper clip float on top of the water surface in a container.  

When you drop a paper clip into the water, it sinks to the bottom of the container. But when you drop the paper clip trickily, on top of the water surface, it floats. Because the water molecules stay tightly together by attracting other water molecules and form a strong surface tension due to cohesive forces. This surface tension keeps the paper clip floating on the water surface.

Alcohol is a non-polar liquid body that holds very less surface tension when compared to water. As alcohol is non-polar, it does not form hydrogen bonds. Without hydrogen bonds there is no cohesive forces and no surface tension making the paper clips sink in the water! Hence, it is highly impossible for a paper clip to float on alcohol.

When you add some detergent to the water on which a paper clip is floating, the surface tension of water gets disturbed. Due to the thin layer of soapy liquid of detergent, the surface tension of water breaks. When the surface tension gets disturbed the water molecules loose enough strength to hold the water molecules together. And the water surface area loses its surface tension due to lack of attraction between the water molecules. Finally causes the floating paper clip to sink to the bottom of the bowl containing full of water.

Tooth picks float on water surface because they naturally come with flat surface and made of wood. Flat surfaces do not sink into the water instead float on top of the water surface naturally. Because of their light weight and surface tension of water, the tooth picks float amazingly on top of the water.

Paper clips float on the surface area of the water because of surface tension. Surface tension is the tendency of liquid molecules to attract each other due to cohesive forces. In floating paper clip science experiment, the water molecules on the surface area attract each other and stay tight due to cohesive force. Thus forms the strong surface tension on the top layer of water in the bowl. When you push the paper clip, due to strong force the surface tension breaks and sinks the paper clip float.  

Naturally, paper clip is a metal material i.e. steel and stays separated from other paper clips when placed together in a container. However, they become magnetised when we use strong magnets to make the paper clips float. This is because steel easily gets attracted to magnets and becomes slightly magnetic but loses its magnetism soon after you remove the magnet away.  

Yes, absolutely we can increase the surface tension of water using salt. Salt is the magical kitchen hold ingredient that surprisingly increases the water surface tension. All you need to do is just add a little amount of salt to the fresh water taken in a container. That’s it! The surface tension of water increases amazingly. You can observe this by doing some surface tension experiments like floating paper clip, magnet paper clip, etc.

Water is an odourless, tasteless, and calorie less inorganic compound that has strong surface tension i.e. 72.8millinewtons (mN) per meter at 20 °C. There are other liquids that show strongest surface tension such as mercury. Whereas alcohol and benzene shows less surface tension compared to water and mercury.

It all depends on the surface tension. You can keep on adding paper clips to the water surface carefully until the surface tension of the water in the container holds. Make sure you are dropping paper clip one after the other carefully on the surface tension of the water. When you drop paper clips one by one, they start sticking to each other because of the forces acting inside the liquid surface area.

Because of higher surface tension on the water, the paper clip is able to float when placed on quizlet. The water molecules stay tightly together and remain closely forming skin of the water surface due to the cohesive forces inside it. This skin of the water surface is nothing but the surface tension which makes paper clips float on the water surface area.

Floating paper clips with magnets is an interesting and exciting science activity using everyday supplies in the home. Here are the instructions to do: 1) Take 5-6 inch long thread and tie it to one end of the paper clip 2) Now glue the other free end of the thread to the immobile object in the home like tables, desks, etc. Whatever you use, you need to perform the experiment near that object only. 3) Place a magnet just above the paper clip and make sure the magnet is not touching the paper clip. Just bring it near to the paper clip. 4) As the paper clip is metal, it gets attracted to the magnet and starts moving towards magnet which seem like the paper clip is floating.

As human body is much stronger and has great gravitational force, it is impossible for them to walk on water surface. Because of these two reasons, the humans overcome the surface tension of water. Whereas the small tiny insects walk across the surface layer of lake water because of string surface tension of water molecules on the lake. As insects are small in size and light in weight cannot overcome the strong surface tension of water. Thus, it is easy for tiny insects to walk across the water.

The densest liquid on Earth’s atmosphere is Mercury or Quick Silver. Mercury is the best known liquid since 3500 years and stays stable at STP i.e. standard conditions of pressure and temperature. In addition, mercury proves to have higher surface tension than water and known as second highest surface tension liquid after water.

Time requires: It just requires 3-5 minutes of your free time. As it is a simple and quick activity, you can even perform it on your busy day during play time as well.

Age Group: Kids of all age group are perfect to investigate this simple science activity. Especially the older kids learn the science concepts in an easy and educational way while having a lot of fun. Kindergarten, elementary, and pre-school children can also perform this activity during their free time and learn about water molecules.

Safety measures: This activity is completely safe as we are not using any single toxic material or substances. The only thing we need consider is paper clips. As paper clips are tiny, there are chances by younger children to keep it inside the mouth. So, adult supervision is mandatory when you perform this activity with toddlers, and kindergarten. It is always suggestible to wear safety goggles and gloves while performing the activity.

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February 1, 2018

Use Surface Tension to Make Pepper Dance!

A kitchen science activity from Science Buddies

By Science Buddies & Megan Arnett

Can you make your spices zoom around--with just a little tension? 

George Retseck

Key concepts Physics Cohesion Surface tension Hydrophobic

Introduction Water. You can drink it, splash it, dive into it, float things in it. But it has its strange side: it flows, but then on some surfaces, it won’t flow, it’ll just roll up into a little bead. And on still ponds outside, in shady areas, you can sometimes see small insects with long legs walking around—on top of the water. What’s up with that? Today you’re going to learn about how water has something called “surface tension” that you can see and play around with by doing some very easy experiments.

Background Water molecules like to cling to one another through the bonds in their hydrogen atoms. The strength of this cohesive force allows the molecules to act similar to an elastic membrane on the water’s surface. This creates surface tension, a property of a liquid that allows it to resist external forces including the weight of a small bug or the force of gravity trying to pull water into a flat puddle! If you drop a small amount of water on a piece of wax paper, you can see a great example of surface tension in action. Instead of splashing or flattening, the water will form small, hemispherical droplets on the paper. These water droplets can hold their shapes because water molecules are more attracted to one another than they are to the wax paper. The strength of that attraction helps hold a water droplet together.

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In this activity we’ll be exploring surface tension with water and some household products. Get ready to make a splash!

Ground black pepper—at least five teaspoons

A shallow bowl or aluminum pie tin (Something light in color works best.)

Liquid dishwashing soap

Cooking oil

Glass cleaner

Five toothpicks

An adult helper

Pencil (or pen)

Access to a sink

Preparation

Use your paper and pencil to create a table with two columns and six rows. Label the first column “household product” and the second column “behavior of pepper.” Add the following words to the rows in the left column: “oil,” “dishwashing liquid,” “glass cleaner,” “milk” and “toothpaste.” This will help you record your observations during this activity.

Gather your materials on a surface that can withstand spills.

This activity uses household chemicals that, if handled incorrectly, can be dangerous. Please have an adult help you!

Fill your bowl or pan two thirds full of water.

Sprinkle one teaspoon of black pepper over the water. Observe the behavior of the pepper. Does the pepper sink or float? Does it spread out or clump together? What else do you notice about the pepper?

Carefully dip the end of your toothpick into the cooking oil. You only need a tiny bit of oil at the end of the toothpick!

Dip the oil-coated end of the toothpick into the water with the pepper. Observe what happens when the oil comes in contact with the water. Does the movement of the pepper flakes on the surface of the water change when you add oil? What else do you notice about the oil and the pepper?

Write your observations in your table. Discard the toothpick.

Empty and rinse your bowl.

Again, fill the bowl two thirds full of water.

Sprinkle one teaspoon of black pepper over the water. Again take a minute to observe how the pepper moves in the water.

Carefully dip the end of a clean toothpick into dishwashing liquid.

Dip the dishwashing liquid end of the toothpick into the water with the pepper. Observe what happens when the dishwashing liquid comes in contact with the water. Does the movement of the pepper flakes on the water’s surface change when you add the dishwashing liquid? In what way?

Write your observations in your table. Discard the dishwashing liquid toothpick.

Empty and rinse your bowl with water.

Sprinkle a teaspoon of black pepper over the water. Again take a minute to observe how the pepper moves in the water.

Repeat these steps with each of the remaining testing ingredients. Rinse and refill the bowl with clean water between each ingredient. Record your observations in your table.

Extra: Repeat this activity, testing with other household supplies. Do you notice a pattern in which products affect the pepper and which don’t?

Extra: Repeat this activity testing what happens when you use juice or soda instead of water.

Observations and results During this activity you tested five different household products to see how they affected the movement of pepper flakes in water. The first thing you may have noticed is that at least some of the pepper flakes floated on the water’s surface. Pepper is hydrophobic, which means water is not attracted to it. Therefore, unlike salt or sugar pepper will not dissolve in water. The pepper is able to float on the surface because water molecules like to cling to one another. They arrange themselves in a way that creates surface tension on the top of the water. This tension keeps the pepper flakes floating on top instead of sinking to the bottom of the bowl.

You should have observed a change in the behavior of the pepper flakes when you added different household products. Adding three of the products—the dishwashing liquid, glass cleaner and toothpaste—to the water should all have caused the pepper flakes to instantly dart away from the toothpick. In contrast the oil and milk should have had very little or no effect on the pepper’s behavior, although you could probably see the oil droplet floating on the surface. Before we break down why this happens can you think of anything that dishwashing liquid, glass cleaner and toothpaste have in common?

If you said that they all clean things—you’re right! And that important trait helps explain why the pepper was chased away by each of those three products. Soaps and cleaners are designed to break down the surface tension of water. This helps make them good cleaning tools. When you add the dishwashing liquid, toothpaste or glass cleaner to the water it breaks up the surface tension. The water molecules, however, want to stick together and maintain that tension, so they move away from the soap, carrying the pepper with them!

Clean up Discard any remaining liquid down the drain and throw away any used toothpicks.

More to explore Measuring the Surface Tension of Water , from Science Buddies Build a Raft Powered by Surface Tension , from Science Buddies Surfactant Science: Make a Milk Rainbow , from Scientific American Make a Paper Fish Swim with Surface Tension , from Scientific American Science Activities for All Ages ! from Science Buddies

This activity brought to you in partnership with Science Buddies

Editor’s Note (5/6/20): This story has been edited after posting to correct descriptions of how surface tension works.

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How to Measure Surface Tension

Last Updated: November 4, 2022 Fact Checked

This article was co-authored by Bess Ruff, MA . Bess Ruff is a Geography PhD student at Florida State University. She received her MA in Environmental Science and Management from the University of California, Santa Barbara in 2016. She has conducted survey work for marine spatial planning projects in the Caribbean and provided research support as a graduate fellow for the Sustainable Fisheries Group. There are 11 references cited in this article, which can be found at the bottom of the page. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 160,254 times.

Surface tension refers to the ability of a liquid to resist the force of gravity. For example, water forms droplets on a table because the water molecules at the surface group together against the force of gravity. [1] X Trustworthy Source Science Buddies Expert-sourced database of science projects, explanations, and educational material Go to source Surface tension is what allows a denser object, such as an insect, to be able to float on the water's surface. Surface tension is measured by the amount of force (N) exerted on a unit such as length (m) or the amount of energy of a measured area. These are measured as Newton per meter (or N/meter). [2] X Trustworthy Source Science Buddies Expert-sourced database of science projects, explanations, and educational material Go to source The forces that water molecules exert on each other, or cohesive forces, cause the tension and are responsible for the shape of water (or other liquid) drops. You can measure surface tension with a few household items and a calculator.

Measuring Surface Tension with a Balance Beam

• The force will be calculated at the end of the experiment.
• Measure the length of the needle in meters using a ruler before starting the experiment.

• Mark the center of the material to be used for your beam (straw, plastic ruler) and drill or poke a hole through it; this will be the fulcrum point (the point that allows the beam to rotate freely). If you are using a plastic straw you can just poke a pin or nail right through it.
• Drill or poke a hole at each end of the beam ensuring that they are the same distance from the middle. Thread a string through each hole to serve as holders for the balance dishes. Make sure that there is 1 string for each hole at either end.
• Rest the nail horizontally between two stacks of books so that the center beam can rotate freely.

• Hang the box or dish from one end of the beam. Poke small holes in the sides of the dish and thread the string through to hold up the dish.

• This is called counterbalancing. The clay does not affect the calculations because it is balancing out the beam.

• Make sure the string holding the needle in place remains taut once the needle is on top of the water.

• Count out a number of pins or drops of water and weigh them.
• Determine the individual weight of each drop or pin by dividing the total weight by the number of pins or water drops.
• For example, let’s say 30 pins weigh 15 grams: 15/30 = 0.5. Each pin weighs 0.5 grams.

• Count the number of pins or drops of water needed to remove the counterweight from the water's surface.
• Record each reading.
• Repeat the exercise several times (5 or 6) for more accurate readings.
• Calculate an average of the results by adding the total number of pins needed in each trial and dividing that by the total number of trials.

• Multiply the number of pins added to the dish by the weight of each pin. For example, 5 pins at 0.5 g/pin = 5 x 0.5 = 2.5 g.
• Multiply the amount of grams by the conversion factor 0.00981 N/g: 2.5 x 0.00981 = 0.025 N.

• Continuing our example, let’s say the needle was 0.025 m long. Plugging the variables into the equation yields: S = F/2d = 0.025 N/(2 x 0.025) = 0.05 N/m. The surface tension of the liquid is 0.05 N/m.

Measuring Surface Tension with Capillary Action

• The height the liquid rises can be used to calculate the surface tension of that liquid.
• Cohesion causes water to form bubbles or droplets on a surface. When a liquid is in contact with air, the molecules feel attractive forces towards each other and make a bubble on the surface.
• Adhesion causes the meniscus that is seen in liquids when they cling to the sides of a glass. It is the concave shape at the top of the liquid seen at eye level. [7] X Research source
• An example of capillary action is watching water rise in a straw placed in a cup of water.

• When working through this equation, make sure all of your units are in the proper metric form: density in kg/m 3 , height and radius in meters, and gravity in m/s 2 .
• If the density of the liquid is not given, you can look it up in a reference book or calculate it using the equation density = mass/volume.
• The unit for surface tension is one newton per meter (N/m). A Newton is equal to 1 kg-m/s 2 . To work out the units on your own, simply solve the equation with just units. S = kg/m 3 * m * m/s 2 * m. Two of the meter units cancel out two of the per meter units and you are left with 1 kg-m/s 2 /m or 1 N/m.

• If you repeat this with different liquids, make sure the dish is thoroughly cleaned and dried before adding the next liquid. Alternatively, just use separate dishes for each liquid.

• To measure the radius, simply place a ruler across the top of the tube and determine the diameter. Divide the diameter by 2 and you have the radius.
• You can buy these tubes online or from a hardware store.
• It can be difficult to accurately measure small changes in the height the liquid will rise in a straw or wide tube. As the height to which the water will rise is inversely proportional to the diameter of the tube (narrower tube = higher rise) this experiment is much easier to do with a narrow transparent capillary tube. These can be purchased at low cost online, but confirm the inside diameter is provided (typically around 1mm-1.2mm) and both ends are open. As these are fragile and made of glass, ensure care when handling them.

• For example, let’s say we are measuring the surface tension of water. Water has a density around 1000 kg/m 3 (we will use approximate values in this example). [12] X Research source The variable g is always 9.8 m/s 2 . The radius of the tube is .029 m and the water rises 0.0005 m. What is the surface tension of the water?
• Plugging the variables into the equation yields: S = (ρhga/2) = (1000 x 9.8 x 0.029 x 0.0005)/2 = 0.1421/2 = 0.071 J/m 2 .

Measuring Relative Surface Tension with a Penny

• Make sure the penny is completely clean and dry before beginning the experiment. If there are other liquids on the penny, the experiment will not be accurate.
• This experiment does not allow you to calculate surface tension, but just determine surface tensions of different liquids relative to each other.

• Write down how many drops it takes for the liquid to flow over the side of the penny.

• Try mixing a little bit of dish soap to the water and dropping again to see if the surface tension changes.

• Substances with a higher surface tension will have more drops on the penny than substances with a lower surface tension.
• The dish soap lowers the surface tension of the water, using fewer drops to fill the penny.

Community Q&A

Things You'll Need

• Straw, plastic ruler or other stiff rod
• Aluminum foil
• Modeling clay or other similar material
• Long needle or nail for fulcrum
• Paper clip or needle to submerge into water
• Books or other material of equal weight to support the balance beam
• Small container
• Eye dropper, pipette or pins
• Postal scale or other small weighing device
• Shallow dish

You Might Also Like

• ↑ http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p021.shtml#background
• ↑ http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p012.shtml#background
• ↑ https://csef.usc.edu/History/2015/Projects/J1710.pdf
• ↑ http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p012.shtml#procedure
• ↑ https://www.teachengineering.org/view_lesson.php?url=collection/duk_/lessons/duk_surfacetensionunit_lessons/duk_surfacetensionunit_less2.xml
• ↑ https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/States_of_Matter/Properties_of_Liquids/Capillary_Action
• ↑ https://pressbooks.uiowa.edu/clonedbook/chapter/cohesion-and-adhesion-in-liquids-surface-tension-and-capillary-action/
• ↑ https://chem.libretexts.org/Courses/Oregon_Institute_of_Technology/OIT%3A_CHE_202_-_General_Chemistry_II/Unit_7%3A_Intermolecular_and_Intramolecular_Forces_in_Action/7.1%3A_Surface_Tension%2C_Viscosity%2C_and_Capillary_Action
• ↑ http://www.engineeringtoolbox.com/water-density-specific-weight-d_595.html
• ↑ https://www.scientificamerican.com/article/measure-surface-tension-with-a-penny/
• ↑ https://www.sciencebuddies.org/science-fair-projects/project-ideas/Chem_p021/chemistry/measuring-surface-tension-of-water-with-a-penny

About This Article

To measure surface tension using the capillary method, fill a shallow dish with 1 inch of water. Measure the radius of a clear tube, then place the tube in the water and measure how high the water in the tube rises above the water in the container. Plug the measured value into your equation to calculate the surface tension. For more information on measuring surface tension from our Environmental Science reviewer, including how to calculate relative tension with a penny, keep reading. Did this summary help you? Yes No

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Go on a hands-on adventure at heilbronn’s experimenta science center.

The Experimenta Science Center in Heilbronn, Germany, seen on June 16, 2024, attracts more than 1,000 visitors daily with its engaging science and technology exhibits. (Alexander Riedel/Stars and Stripes)

You’ve probably heard of the butterfly effect, but what about the Brazil nut effect? Imagine shaking a can of mixed nuts and finding that the largest, like Brazil nuts, have risen to the top.

Also known as granular convection, this phenomenon, in which larger particles end up on the surface while smaller ones settle at the bottom, is just one of many that can be explored hands-on at the Experimenta Science Center in Heilbronn, Germany.

Experimenta is a playground consisting of a changing array of 275 interactive exhibits designed to engage visitors. My wife, a passionate biologist, and I recently spent a Sunday afternoon there and got lost in the experiments.

From the moment we entered, we were immersed in a world of discovery. At the door we were issued RFID bracelets to interact with the exhibits. These bracelets allowed us to save images and videos of our experiments, which we could access later at home.

The technology added a layer of engagement, making the learning process even more enjoyable. Best of all, each experiment is explained fully in English, leaving nothing to guesswork or cumbersome cellphone translation.

We started by exploring the various materials making up a car, and a wind studio where we could feel the effects of varying wind speeds and capture fun selfies in a wind tunnel. This wasn’t just child’s play; the science behind aerodynamics was right at our fingertips.

A young girl examines the textures and shapes of sea shells and pine cones at the Experimenta Science Center in Heilbronn, Germany, where interactive exhibits engage visitors of all ages in hands-on learning. (Alexander Riedel/Stars and Stripes)

A visitor uses a heat camera to explore the conduction of heat and cold through different materials at the Experimenta Science Center in Heilbronn, Germany. (Alexander Riedel/Stars and Stripes)

A guest scans an RFID chip at an interactive station in the Experimenta Science Center, allowing them to save images and videos of their experiments for later access. (Alexander Riedel/Stars and Stripes)

Brazil nuts rose to the top of a container of rice, demonstrating the Brazil nut effect, one of the many intriguing phenomena explored at the Experimenta Science Center in Heilbronn, Germany. (Alexander Riedel/Stars and Stripes)

One exhibit that stood out involved exploration of different materials like plastics, metals and leather, and understanding how they conduct heat, light and electricity.

On the second floor, the focus shifted to sensory experiences. We navigated a dark room that tested our eyes’ perception of colors and examined how refraction and wavelengths of light allow us to see.

Another activity tested our sense of smell, which can sometimes be deceptive. We identified scents from metal dispensers activated by pressing a button, before revealing the source of the aroma.

The third floor, dubbed WeltBlick, or “World View,” afforded us the chance to study weather phenomena. Other stations showcased mold and fungal spores, and we could observe microscopic organisms.

Some stations are more scientific than others. One exhibit that made us laugh and think was the dropped-sandwich experiment. It tested the age-old question “Does a dropped slice of bread always land butter-side down?”

Using different heights and recording our results, we engaged in a simple yet effective demonstration of the scientific process and probability. Spoiler alert: Nature often conspires against your lunch.

The buttered bread experiment at the Experimenta Science Center tests whether a dropped slice always lands butter-side down, and how many times it turns. (Alexander Riedel/Stars and Stripes)

A visitor tries to sneak past a computer-screen samurai by stepping carefully on sound-sensitive floorboards at the ninja obstacle course in the Experimenta Science Center. (Alexander Riedel/Stars and Stripes)

A family explores the world of microorganisms at the Experimenta Science Center, observing microscopic life and learning about complex biological systems. (Alexander Riedel/Stars and Stripes)

A boy tests his balance on a circular cycling station at the Experimenta Science Center, discovering the principles of physics and motion. (Alexander Riedel/Stars and Stripes)

The packaging station explores the effect of color, shape and materials of packaging on marketing and perception by allowing visitors to select appropriate packaging for different products and comparing their selection against other visitors’. (Alexander Riedel/Stars and Stripes)

One particularly whimsical exhibit was the ninja challenge, where we tried to sneak up to a computer-screen samurai by stepping carefully on sound-sensitive floorboards. It was a playful way to understand sound and movement.

In the Explorer Land area, we found a water playground where kids could build obstacles and observe water flow dynamics by letting small plastic balls travel through a whirlpool and be elevated by high-pressure streams.

I also enjoyed the Strandbeesten, Dutch for beach beasts, which are lightweight, wind-driven constructs that mimic animal-like movements. Watching these wooden structures come to life highlighted the beauty of engineering and design.

Experimenta’s highlight arguably is the Science Dome, a combination of a planetarium and theater that is worth a visit on its own. With 3D glasses, visitors embark on a virtual journey through space, enhanced by laser effects.

While we missed out on it during our visit, the center also features Germany’s first all-sky cupola, offering an immersive look into space when the weather is right.

A girl plays with a small Strandbeesten, wind-driven constructs that mimic animal movements, at the Experimenta Science Center, in Heilbronn, Germany. (Alexander Riedel/Stars and Stripes)

Two kids play in the wind tube station, exploring how air pressure can transport items in a vacuum at the Experimenta Science Center. (Alexander Riedel/Stars and Stripes)

A visitor listens to an audio guide at a nature station, learning about how trees grow and the science behind their development at the Experimenta Science Center in Heilbronn, Germany. (Alexander Riedel/Stars and Stripes)

A family works together on lighting fixtures in the Maker Lab at the Experimenta Science Center. The lab features instructors that walk visitors through guided creative experiments with a variety of materials. (Alexander Riedel/Stars and Stripes)

A girl tries the air parcour hang glider station at the Experimenta Science Center, learning about aerodynamics and balance in a fun and interactive way. (Alexander Riedel/Stars and Stripes)

Every exhibit is clearly designed to be accessible and engaging for children. But I found it particularly amusing to watch adults of all ages find themselves just as captivated as their youngsters.

My wife and I both found ourselves engrossed in the stations, turning into big kids as we experimented and learned a thing or two along the way.

Our three hours flew by — a sign of the relativity of time, perhaps — but we barely managed to scratch the surface of all that Experimenta had to offer.

Address: Experimenta-Platz, Heilbronn, Germany

Hours: Monday-Friday, 9 a.m.-5 p.m.; Saturday, Sunday and holidays 10 a.m.-6 p.m. 

Cost: Entry is 12 euros per adult; kids under 18 pay 6 euros or free for children under 3. A not-so-secret tip: Experimenta has its own adjacent parking garage, which is more convenient than the nearby city car park. Validate tickets at the Experimenta ticket counter for a reduced rate.

Online: experimenta.science

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Response Surface Model for Mechanical Properties of Robotically Stitched Composites

• Published: 27 June 2024

Cite this article

• Radwa Alaziz 1 ,
• Shuvam Saha 1 &
• Rani W. Sullivan 1  

Composite structures are extensively used in several industries such as aerospace, automotive, sports, and construction due to their many advantages, including tailorable mechanical properties, high strength-to-weight ratios, and high specific stiffness. However, due to their low interlaminar tensile and shear strength, composites are prone to delaminations, which can degrade the overall mechanical performance of the structure. Through-thickness stitching provides a third-direction reinforcement to enhance the interlaminar tensile and shear strengths. In this study, quasi-isotropic composite test specimens were manufactured with a novel through-thickness robotic chain stitching with different patterns and tested under uniaxial tensile and three-point bend loadings. A design of experiments (DoE) approach was used to investigate the influence of stitch parameters (stitch density, stitch angle, and linear thread density) on the tensile strength, tensile modulus, and flexural strength of stitched composites. Experimental results are then used to develop a statistically informed response surface model (RSM) to find optimal stitching parameters based on a maximum predicted tensile strength, tensile modulus, and flexural strength. This study reveals and discusses the optimum selection of stitch processing parameters to improve the in-plane and out-of-plane mechanical properties.

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Data Availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Alaziz, R., Sullivan, R.W.: Investigation of damage in composite structures under vibration using Hilbert-Huang transform. Proceedings of the American Society for Composites - 34th Technical Conference, ASC (2019). https://doi.org/10.12783/asc34/31417

Mouritz, A.P., Leong, K.H., Herszberg, I.: A review of the effect of stitching on the in-plane mechanical properties of fibre-reinforced polymer composites. Compos. Part. A. Appl. Sci. Manuf.  28 , 979–991 (1997). https://doi.org/10.1016/S1359-835X(97)00057-2

Article   Google Scholar  

Mouritz, A.P., Cox, B.N.: A mechanistic interpretation of the comparative in-plane mechanical properties of 3D woven, stitched and pinned composites. Compos. Part. A. Appl. Sci. Manuf.  41 , 709–728 (2010). https://doi.org/10.1016/j.compositesa.2010.02.001

Mouritz, A.P., Cox, B.N.: A mechanistic approach to the properties of stitched laminates. Compos. Part. A. Appl. Sci. Manuf.  31 , 1–27 (2000). https://doi.org/10.1016/S1359-835X(99)00056-1

Velicki, A., Thrash, P.: Damage arrest design approach using stitched composites. Aeronaut. Journal. 115 , 789–795 (2011). https://doi.org/10.1017/S0001924000006539

Yudhanto, A., Lubineau, G., Ventura, I.A., Watanabe, N., Iwahori, Y., Hoshi, H.: Damage characteristics in 3D stitched composites with various stitch parameters under in-plane tension. Compos. Part. A. Appl. Sci. Manuf. 71 , 17–31 (2015). https://doi.org/10.1016/J.COMPOSITESA.2014.12.012

Larsson, F.: Damage tolerance of a stitched carbon/epoxy laminate. Compos. Part. A. Appl. Sci. Manuf. (1997). https://doi.org/10.1016/S1359-835X(97)00063-8

Tan, K.T., Yoshimura, A., Watanabe, N., Iwahori, Y., Ishikawa, T.: Effect of stitch density and stitch thread thickness on damage progression and failure characteristics of stitched composites under out-of-plane loading. Compos. Sci. Technol. 74 , 194–204 (2013). https://doi.org/10.1016/j.compscitech.2012.11.001

Article   CAS   Google Scholar  

Mouritz, A.P.: Fracture and tensile fatigue properties of stitched fibreglass composites. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications. 218 , 87–93 (2004). https://doi.org/10.1177/146442070421800203

Yoshimura, A., Yashiro, S., Okabe, T., Takeda, N.: Characterization of tensile damage progress in stitched CFRP laminates. Adv. Compos. Mater. 16 , 223–244 (2007). https://doi.org/10.1163/156855107781393740

Yudhanto, A., Watanabe, N., Iwahori, Y., Hoshi, H.: Compression properties and damage mechanisms of stitched carbon/epoxy composites. Compos. Sci. Technol. 86 , 52–60 (2013). https://doi.org/10.1016/j.compscitech.2013.07.002

Tan, K.T., Watanabe, N., Iwahori, Y.: Impact damage resistance, response, and mechanisms of laminated composites reinforced by through-thickness stitching. Int. J. Damage. Mech. 21 , 51–80 (2011). https://doi.org/10.1177/1056789510397070

Herwan, J., Kondo, A., Morooka, S., Watanabe, N.: Effects of stitch density and stitch thread thickness on mode II delamination properties of Vectran stitched composites. Plast. Rubber. Compos. 43 , 300–308 (2014). https://doi.org/10.1179/1743289814Y.0000000103

Xuan, J., Li, D., Jiang, L.: Fabrication, properties and failure of 3D stitched carbon/epoxy composites with no stitching fibers damage. Compos. Struct. 220 , 602–607 (2019). https://doi.org/10.1016/j.compstruct.2019.03.080

Song, C., Fan, W., Liu, T., Wang, S., Song, W., Gao, X.: A review on three-dimensional stitched composites and their research perspectives. Compos. Part. A. Appl. Sci. Manuf. 153 , 106730 (2022). https://doi.org/10.1016/j.compositesa.2021.106730

Aymerich, F., Priolo, P., Sun, C.T.: Static and fatigue behaviour of stitched graphite/epoxy composite laminates. Compos. Sci. Technol. 63 , 907–917 (2003). https://doi.org/10.1016/S0266-3538(02)00314-7

Yudhanto, A., Watanabe, N., Iwahori, Y., Hoshi, H.: Effect of stitch density on tensile properties and damage mechanisms of stitched carbon/epoxy composites. Compos. B. Eng. 46 , 151–165 (2013). https://doi.org/10.1016/j.compositesb.2012.10.003

Kang, T.J., Lee, S.H.: Effect of Stitching on the Mechanical and Impact Properties of Woven Laminate Composite. J. Compos. Mater. 28 , 1574–1587 (1994). https://doi.org/10.1177/002199839402801604

Dickinson, L.C.: A Designed Experiment in Stitched/RTM Composites. NASA. Langley Research Center, Third NASA Advanced Composites Technology Conference, Volume 1, Part 1 (1993)

Nie, J., Xu, Y., Zhang, L., Yin, X., Cheng, L., Ma, J.: Effect of stitch spacing on mechanical properties of carbon/silicon carbide composites. Compos. Sci. Technol. 68 , 2425–2432 (2008). https://doi.org/10.1016/j.compscitech.2008.04.012

Zhao, N., Rödel, H., Herzberg, C., Gao, S.-L., Krzywinski, S.: Stitched glass/PP composite. Part I: Tensile and impact properties. Compos. Part. A. Appl. Sci. Manuf. 40 , 635–643 (2009). https://doi.org/10.1016/J.COMPOSITESA.2009.02.019

Alaziz, R., Saha, S., Sullivan, R.W., Tian, Z.: Influence of 3-D periodic stitching patterns on the strain distributions in polymer matrix composites. Compos. Struct. 278  (2021)

Cecen, V., Sarikanat, M., Seki, Y., Govsa, T., Yildiz, H., Tavman, I.H.: Polyester composites reinforced with noncrimp stitched carbon fabrics: Mechanical characterization of composites and investigation on the interaction between polyester and carbon fiber. J. Appl. Polym. Sci. 102 , 4554–4564 (2006). https://doi.org/10.1002/app.24983

Wu, E., Wang, J.: Behavior of Stitched Laminates under In-Plane Tensile and Transverse Impact Loading. J. Compos. Mater. 29 , 2254–2279 (1995). https://doi.org/10.1177/002199839502901702

Jain, L.K., Dransfleld, K., Mai, Y.W., Baillie, C.: Improvement of interlaminar properties in advanced fibre composites with through-thickness reinforcement. Cooperative Research Centre for Aerospace Structures Ltd., CRC-AS TM94012. (1994)

Mouritz, A.P., Gallagher, J., Goodwin, A.A.: Flexural strength and interlaminar shear strength of stitched GRP laminates following repeated impacts. Compos. Sci. Technol. 57 , 509–522 (1997). https://doi.org/10.1016/S0266-3538(96)00164-9

Cholakara, M.T., Jang, B.Z., Wang, C.Z.: Deformation and failure mechanisms in 3D composites. In: International SAMPE Symposium and Exhibition (Proceedings). pp. 2153–2160 (1989)

Mouritz, A.P.: Flexural properties of stitched GRP laminates. Compos. Part. A. Appl. Sci. Manuf. 27 , 525–530 (1996). https://doi.org/10.1016/1359-835X(96)00010-3

Chung, W.C., Jang, B.Z., Chang, T.C., Hwang, L.R., Wilcox, R.C.: Fracture behavior in stitched multidirectional composites. Mater. Sci. Eng. A. 112 , 157–173 (1989). https://doi.org/10.1016/0921-5093(89)90355-9

Flanagan, G., Furrow, K.: Parametric studies of stitching effectiveness for preventing substructure disbond. In: NASA Technical Report. p. 539. NASA (1995)

Bilisik, K., Erdogan, G., Sapancı, E.: Flexural behavior of 3D para-aramid/phenolic/nano (MWCNT) composites. RSC Adv. 8 , 7213–7224 (2018). https://doi.org/10.1039/C7RA13437A

Article   CAS   PubMed   PubMed Central   Google Scholar  

Bilisik, K., Karaduman, N.S., Sapanci, E.: Flexural characterization of 3D prepreg/stitched carbon/epoxy/multiwalled carbon nanotube preforms and composites. J. Compos. Mater. 53 , 563–577 (2018). https://doi.org/10.1177/0021998318787861

Drake, D.A., Sullivan, R.W., Lacy, T.E., Pittman, C.U., Toghiani, H., Dubien, J.L., Nouranian, S., Simsiriwong, J.: Creep characterization of vapor-grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology. J. Appl. Polym. Sci. 132 ,(2015). https://doi.org/10.1002/app.42162

Montgomery, D.C.: Design and analysis of experiments, 2nd edn., p. ©1984. Wiley, New York (1984)

Google Scholar  

Drake, D.A., Sullivan, R.W., Clay, S.B., DuBien, J.L.: Influence of stitching on the fracture of stitched sandwich composites. Compos Part A Appl Sci Manuf 145 , 106383 (2021). https://doi.org/10.1016/J.COMPOSITESA.2021.106383

Tamakuwala, V.R.: Manufacturing of fiber reinforced polymer by using VARTM process: A review. Mater. Today. Proc. 44 , 987–993 (2021). https://doi.org/10.1016/j.matpr.2020.11.102

Göktaş, D., Kennon, W.R., Potluri, P.: Improvement of Mode I Interlaminar Fracture Toughness of Stitched Glass/Epoxy Composites. Appl. Compos. Mater. 24 , 351–375 (2017). https://doi.org/10.1007/s10443-016-9560-x

Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials. Tech. Rept. ASTM D3039/D3039M 17, ASTM International, West Conshohocken, PA. (2017)

Gom. 23 May. 2019: Web, http://gom.com/

Kashfuddoja, M., Prasath, R.G.R., Ramji, M.: Study on experimental characterization of carbon fiber reinforced polymer panel using digital image correlation: A sensitivity analysis. Opt. Lasers. Eng. 62 , 17–30 (2014). https://doi.org/10.1016/j.optlaseng.2014.04.019

Standard Test Method for Flexural Properties of Polymer Matrix Composite Materials. Tech. Rept. ASTM D7264/D7264M-07, ASTM International, West Conshohocken, PA. (2015)

Yaakob, M.Y., Husin, M.A., Abdullah, A., Mohamed, K.A., Khim, A.S., Fang, M.L.C., Sihombing, H.: Effect of stitching patterns on tensile strength of kenaf woven fabric composites. Int. J. Intr. Eng. 11 , 070–079 (2019). https://doi.org/10.30880/ijie.2019.11.06.008

Dincer, M., Karci, E., Halil Sahin, I., Emre, C., Ozkendirci, B., Ozden Yenigun, E., Cebeci, H.: Effect of linear density on the mechanical properties of 3D spacer composites with improved manufacturing quality. Compos. Struct. 323 ,(2023) https://doi.org/10.1016/J.COMPSTRUCT.2023.117518

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Alaziz, R., Saha, S. & Sullivan, R.W. Response Surface Model for Mechanical Properties of Robotically Stitched Composites. Appl Compos Mater (2024). https://doi.org/10.1007/s10443-024-10245-w

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Response surface methodology for kinematic design of soft pneumatic joints: an application to a bio-inspired scorpion-tail-actuator.

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Antonelli, M.G.; Beomonte Zobel, P.; Stampone, N. Response Surface Methodology for Kinematic Design of Soft Pneumatic Joints: An Application to a Bio-Inspired Scorpion-Tail-Actuator. Machines 2024 , 12 , 439. https://doi.org/10.3390/machines12070439

Antonelli MG, Beomonte Zobel P, Stampone N. Response Surface Methodology for Kinematic Design of Soft Pneumatic Joints: An Application to a Bio-Inspired Scorpion-Tail-Actuator. Machines . 2024; 12(7):439. https://doi.org/10.3390/machines12070439

Antonelli, Michele Gabrio, Pierluigi Beomonte Zobel, and Nicola Stampone. 2024. "Response Surface Methodology for Kinematic Design of Soft Pneumatic Joints: An Application to a Bio-Inspired Scorpion-Tail-Actuator" Machines 12, no. 7: 439. https://doi.org/10.3390/machines12070439

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