water pressure depth experiment

List of Topics

• Feedback Q&A

SfC Home > Science Projects and Experiments >

Fluids Experiment: Show Relationship Between Water Pressure and Depth

by Ron Kurtus (updated 21 November 2022)

You may have noticed when you swim underwater, that the deeper you go the greater the pressure on your ears. You've also probably seen how deep-sea divers must protect themselves against the water pressure at greater depths. This may get you curious as to how to verify the relationship between water pressure and depth.

Finding the relationship between water pressure and depth can be an idea for a science project in the area of physical science . The biggest problem is in measuring water pressure. A clever way to demonstrate increasing water pressure is by showing how far it will squirt from an opening.

Questions you may have include:

• What is the purpose of the experiment?
• What research must be done?
• What is the experiment?

This lesson will answer those questions.

Purpose of experiment

The purpose of the experiment is to demonstrate how water pressure increases with depth. You can also make some rough measurements to show an approximate relationship between depth and water pressure.

Research and factors

It is good to research the physical laws with respect to what pressure is, as well as the concept of increasing pressure in a fluid due to the weight of the fluid. One other research item concerns the relationship between water pressure and how far a stream of water would squirt.

Pressure is force per unit area. At any point in a fluid, the pressure is the same in all directions. Water pressure at a given depth in an open container, such as a swimming pool, is shown by the equation: P = gh , where

• P is the water pressure
• g is the acceleration due to gravity
• h is the depth of the water at that point
• gh is g times h

You know that as you turn up the pressure in a hose, the water squirts out further. So, there is a relationship between pressure and how far the water squirts.

If you had a container with a hole in it, and if it is true that pressure increases with depth, then the water should squirt out further the higher the water level. You could show this by having one hole and measuring how far the water squirts as you change the depth of the water in the container, or you could put several holes at different heights and show how the water squirting varies. 

Note : If you use several holes, they all should be the same size. As you will see in the next experiment the hole size is another variable. You don't want to mix variables in an experiment.

• Large tin can or plastic milk bottle.
• Hammer and nail

Water squirts further at greater depths

• Punch holes in side of the container at one inch intervals.
• Fill the container with water.
• Measure the distance from the container that the water squirts out of each hole.
• Plot a graph of depth (distance of hole from top of water level) versus distance water squirts from can.

Keep records

If this is going to be an experiment for a science fair, you will need to record your activities in a log book.

Draw conclusions

This experiment should verify that since the water squirts out further with increasing depth, that the water pressure increases with depth.

Write report

Write up a report to summarize your results and your proposed solution to the problem.

Since you noticed that the deeper you go in water the greater the pressure on your ears, you can perform an experiment to verify the relationship between water pressure and depth. The biggest problem is in measuring water pressure. A clever way to demonstrate increasing water pressure is by showing how far it will squirt from an opening.

Expand your horizons

Resources and references

Ron Kurtus' Credentials

Experiments Resources

(Notice: The School for Champions may earn commissions from book purchases)

Top-rated books on Science Fair Projects

Top-rated books on Experiments

Students and researchers

The Web address of this page is: www.school-for-champions.com/experiments/ fluids_pressure_depth_relationship.htm

Please include it as a link on your website or as a reference in your report, document, or thesis.

Copyright © Restrictions

Where are you now?

School for Champions

Experiment topics Fluids Experiment: Show Relationship Between Water Pressure and Depth

Science Projects and Experiments

Project preparation.

• Science Project Definition
• Types of Science Projects
• Parts of a Science Project
• Factors in Getting an Idea for a Science Project
• Determine Reasons Students Get Poor Grades
• Control Growth of Mold on Bread
• Overview of Experiments with Fluids
• Volume of Irregularly Shaped Object
• Show Weight in Water is Less than in Air
• Compare the Density of Different Liquids
• Water Pressure and Depth
• Spigot Size versus Fluid Velocity
• Overview of Experiments with Friction
• Measure Coefficient of Friction with a Scale
• Measure Coefficient of Friction with a Ramp

Static Electricity

• Overview of Static Electricity Experiments
• Causing a Balloon to Stick to Things
• Electrical Attraction of a Comb
• Bending Flowing Water
• Control Static Cling
• Make an Electroscope
• Creating Sparks
• Make an Electromagnet

States of Matter

• Overview of States of Matter Experiments
• Temperature versus Changing State
• Use Mpemba Effect to Freeze Hot Water
• Physical Science

Let's make the world a better place

Be the best that you can be.

Use your knowledge and skills to help others succeed.

Don't be wasteful; protect our environment.

You CAN influence the world.

Live your life as a champion:.

Take care of your health

Seek knowledge and gain skills

Do excellent work

Be valuable to others

Have utmost character

Be a Champion!

The School for Champions helps you become the type of person who can be called a Champion .

• Free Resources
• Project Search
• Featured Projects
• Member Benefits

1059 Main Avenue, Clifton, NJ 07011

The most valuable resources for teachers and students

(973) 777 - 3113

[email protected]

1059 Main Avenue

Clifton, NJ 07011

07:30 - 19:00

Monday to Friday

123 456 789

[email protected]

Goldsmith Hall

New York, NY 90210

• Why We’re Unique

Water Pressure

Introduction: (initial observation):.

While watering the grass with a water hose, I tried to use my finger to stop the water a few times, but it didn’t work. The water rushing out of the hose had too much pressure. My friend told me that they don’t have this much pressure at their house. They live up the hill, just a few blocks away. I tried their water hose and could stop it by my hand. That showed me that water pressure is not the same everywhere. I was thinking about this for a while. First, I thought the diameter of the pipe may be a factor, but that wasn’t the case. I checked them out and they both looked the same size. Thinking about this experience raised many questions in my mind.

Now my questions are, why does water have pressure? Do all liquids have pressure? How does the water pressure change at different depths? How can we reduce or increase water pressure? Can we use water pressure to do something, such as lift a car, break a tree, or dig into the ground?

Dear This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “ Ask Question ” button on the top of this page to send me a message.

If you are new in doing science project, click on “ How to Start ” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Information Gathering:

Water pressure is a subject of physics. Therefore, we can search books and web sites related to physics to find information about the science and theory of water pressure. If you search for water pressure, be sure to add the key word “physics” to your search string so that you will be able to find more related information. One of the interesting web sites that I found is a good simulation of water pressure , and can show you why water pressure varies in different areas.

Then I searched for “Industrial applications of water pressure”. I found many good web sites including those describing that water pressure can actually be used as a cutting tool. Waterjet cutting uses a jet of water so powerful that it cuts cleanly and precisely through material in a single pass without shredding or crushing.

About the amount of water pressure! (By the way, I’d like to build a device that measures water pressure at different depths.) I found that even though we do not feel it, 14.7 pounds (lb.) of AIR pressure are pushing down on our bodies as we rest at sea level. Our body compensates for this weight by pushing out with the same force.

Since water is much heavier than air, this pressure increases as we venture into the water. For every 33 feet down we travel, one more atmosphere (14.7 lb.) pushes down on us. For example, at 66 feet, the pressure equals 44.1 lb., and at 99 feet, the pressure equals 58.8 lb.

To travel into this high-pressure environment, we have to make some adjustments. Humans can travel three or four atmospheres and be okay. To go farther, submarines are needed.

Animals that live in this watery environment undergo large pressure changes in short amounts of time. Sperm whales make hour-long dives 7,380 feet (2,250 meters) down. This is a pressure change of more than 223 atmospheres! By studying and understanding how these animals are able to withstand great pressure changes, scientists will be able to build better tools for humans to make such journeys.

Question/ Purpose:

As I said in the introduction section, I have so many questions about water pressure and each of them can be the subject of a different science project. Here I will try to discover as much as possible to answer my questions: Some of my questions are:

Why does water have pressure? Do all liquids have pressure? How does water pressure change at different depths? Is water pressure greater near the surface or in deeper waters? How can we reduce or increase water pressure? Can we use water pressure to do something, such as lifting a car, breaking a tree, or digging into the ground? (I love this part!)

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

Variables for question number 3 can be defined as follows:

The Independent variable (also known as manipulated variable) is the depth.

The dependent variable (also known as responding variable) is the water pressure.

Constants are the type of water, the temperature and experiment method.

Hypothesis:

Since I have so many questions, I also have so many hypothesis!, basically one hypothesis for each question. My hypotheses are as follows:

• I think pressure of water is the result of its weight.
• I think other liquids also must have pressure that varies depending on their specific gravity. (So in a space station there is no water pressure because there is no gravity).
• Water pressure increases by increase in depth. I think water pressure is more at a deeper depth because of the weight of water above.
• I think we can change the pressure by changing the water level. Like the simulation program.
• I think if we have proper equipment, we can use water pressure to lift a car or do anything that requires lots of force.

Experiment Design:

For each hypothesis I will design an experiment to test it. But I first need a tool to measure the water pressure. The device that measures water pressure is called pressure gauge or manometer. Manometers can be purchased from plumbing suppliers, but commercial manometers sold in stores are designed for higher pressures and will not help us with our tests. As a quick solution we will build our own monometer.

How to build a manometer?

The monometer that I will make is a U shaped glass tube with some colored water in it. A flexible plastic tube will be attached to one end of the glass tube. The other end of the plastic tube will be a piece of glass tube that I use as a probe to test water pressure. When there is no pressure, colored water on both sides of the U will be at the same level.

Any pressure will change the balance and cause the colored water to go up in one side and come down on the other side. The height of the U glass above is about 26 cm. The length of the plastic tube is about 50 cm, and the height of the glass tube is about 17cm. Instead of the glass tube, you can use a hard plastic tube or even a flexible plastic tube. It will just take a little more work to secure it and fix it in a straight line. In this manometer, the distance between the water level on the two sides of the U is the pressure. In the picture the pressure of 8 grams per square centimeter is shown.

Experiment 1:

The purpose of this experiment is to see if water weight is causing water pressure.

Water has a weight. It’s specific gravity is 1. In other words, one cubic centimeter of water weighs one gram. If the weight of water is the cause of water pressure, another liquid that is 10% heavier or 10% lighter than water should show a pressure that is 10% higher or 10% lower at the exact same conditions.

We can change the specific gravity or the weight of certain volumes of water by mixing it with a heavy salt, but for this test we will use another liquid such as Isopropyl alcohol that has a specific gravity of 0.78.

Fill up a large cup or a bottle with water. Use your manometer to read the pressure at the depth of 10 cm. Record the result. Next, fill up another cup with Isopropyl alcohol and again measure the pressure at the depth of 10 cm and record the results. If this is the weight of liquid that causes pressure, the pressure of Isopropyl alcohol must be 78% of water pressure at the same depth.

Record your results in a table like this:

Experiment 2:

The purpose of this experiment is to see if all liquids have pressure.

Collect samples of different liquids such as water, Isopropyl alcohol, mineral oil, glycerin, Ethanol (Ethyl alcohol) and test their pressure at a certain depth such as 10 cm. Notice that you don’t have to have large samples of these liquids for testing. Instead of cups or bottles, you can have your samples in test tubes.

Record the results in a table like this:

Experiment 3:

The purpose of this experiment is to see how the pressure of water changes at different depths.

Procedure : (the effect of depth)

• Insert the probe of your nanometer in a glass of water.
• Move it to the left and right. Does the nanometer show any change in pressure?
• Move the probe up and down. Does the manometer show any change in pressure?
• Hold the manometer at 10 different depths and record the pressure for each depth. Record your observations on a table like this:

Simple Experiment:

The purpose of this experiment is to see if water pressure varies in different depths.

Attach a longer flexible tube (about 1 meter) to the manometer so that you could test the pressure at different depths in a bucket of water or in a pool. Keep the manometer probe or tube faced down and take it to different depths while reading the pressure.

Is water pressure different in different depths?

A simpler procedure for this experiment is this one:

Put the end of the straw just below the surface of the water in the jar and blow. Now put the end of the straw near the bottom of the jar and blow again.

Which way is harder to blow bubbles?

In this picture we are using an aneroid manometer to test the water pressure at different depths. Water is not used in the construction of aneroid manometers, so they can be used at almost any condition to test the water pressure. They will even work in low gravity conditions.

Experiment 4: (Similar to the experiment 3)

The purpose of this experiment is to see how can we increase or decrease the water pressure at a certain location?

Independent variable (manipulated variable) is the water level above any point. (The point where we measure water pressure).

Dependent variable (responding variable) is the water pressure at that point.

• A manometer
• A graduated cylinder or any other cylindrical container
• A metric ruler stick that measures centimeters

Place the sensor or probe of the manometer at the bottom of the cylindrical container. Use a piece of tape, a clip or a heavy object to hold the probe at the bottom of the container. (Note that in a home made manometer, the open end of the tube is the sensor or the probe of the manometer.

Insert the ruler in the cylindrical container so you can measure the height of the water. At this time the probe of the manometer (end of the tube) must be at the same level as 0 in your ruler.

Start to add water to the container to the height of 1 cm as shown by the ruler. Read and record the pressure. Add more water so the water level will be at 2, 3, 4,…. 10 centimeters. At each water level observe and record the pressure.

Does increasing the water level increase the water pressure?

Report the results.

Experiment 5: (Try this, you will like it.)

The purpose of this project is to use water pressure to do something useful. Something more than taking a shower or washing the dishes. While searching about water pressure, I read somewhere that the normal water pressure in a town is 45 lbs. That means 45 pounds per square inch. A simple calculation shows that this pressure equals to 6480 lbs per square foot. That is double the weight of a mini van! So in theory, I should be able to lift a minivan by a bag of water about 1 cubic foot attached to a water hose. At this time I will do this experiment in a smaller scale to see how it works. Creating a pressure of 100 grams per square centimeter (100 g/s2) is easy. This is the pressure of a column of water, 100 centimeter tall. 100 g/s2 is about 1.4 lbs per square inch. So it is almost 30 times less than water pressure in our homes. If I be able to lift 100 lbs per square inch with this pressure, that means that lifting a car with the pressure of a water hose should not be a problem.

Variables for this experiment are as follows:

• Independent variable is the water pressure. Water pressure will be calculated based on the level of water in the input tube.
• Dependent variable is the weight lifted,
• Constants are the the pressure area and experiment method.

For this experiment you will need a roll of polyethylene tube. Polyethylene tubes come in roll and that is what companies use to make plastic bags. The tube that you get can be as low as 4 inches up to 20 inches wide. See what you can find. Local hardware store may be a good place to start. You will need about 2 to 5 meters (6 to 15 feet).

Seal one end of your tube and leave the other end open. If you don’t have access to a plastic sealer, just make a big knot to close one end. Or you can cover the end of your plastic tube with aluminum foil and use a hot iron to seal it. (Danger, Danger, Danger…. Don’t burn yourself, get help from adults. Adult supervision is a must).

The first simple test that you can do is to hang your plastic tube from a height of about 2 to 3 feet in a way that about one foot of the tube stays on the ground. Then start filling up the tube with water. When the water goes up the tube about 2 feet, touch the part of the inflated tube that is on the floor with the palm of your hand. Try to push it down. How much pressure do you need to push it down and make it flat? How much weight can this tube carry?

The plastic tube that you see in this picture is a 3MIL polyethylene tube, 4 inches wide.

For second test, put your plastic bag in a box and leave the open end out. Put another piece of cardboard or wood over the plastic bag and place a heavy object on the top of that. Start to add water from the open end. Soon your heavy object should start to rise while the plastic bag gets filled up with water. In this picture shows that we are using a metal can instead of the box, but the results are the same.

If you ever want to use this method to lift a car or any similar heavy object, you need to cover your plastic bag with a strong fabric bag. A plastic bag by itself does not resist high pressure and will burst. By covering it with a strong fabric, you can give it more strength.

The picture on the left is a simple drawing of using a larger plastic bag and inflating it with water pressure. On the right, we filled up a one gallon plastic container and used it as a heavy object. Water pressure raised it 3 inches.

Control experiment can be a similar setup, but you do nothing with that. In other words you don’t add water, so it will not lift any weight. The purpose of having a control experiment is to show that no other external factor is causing our observation.

Other experiments related to water pressure: (For Display)

Make a Cartesian Diver:

Fill a two liter soda bottle with water. Take a medicine dropper and fill it partially, so that the dropper just sinks in the water inside the bottle. It will take some experimentation to find the right amount of water in the dropper. Then put the lid tightly onto the bottle. Squeeze the sides of the bottle. Notice that, as the water pressure inside the bottle is increased thereby, the air in the dropper is compressed, and the dropper falls. You might enjoy repeating the experiment with an oval-shaped bottle. The device is called a Cartesian Diver .

Make an atomizer:

Fill a bottle completely with water, and insert a plastic straw. Hold an inch or two of the straw out of the bottle. By tape or any method of your liking, secure the straw onto the bottle. Blow gently over the straw, either directly or by means of another straw. If possible, use an air pump to force air over the top of the straw. You will notice that water comes out of the bottle. The water is forced up and out of the straw because of the Bernoulli Principle . This mechanism is used in aerosol cans , in that a liquid is ejected from the reservoir by passing a gas over a tube at high speed.

Optional Experiment: Effect of gravity on water pressure

To test the effect of gravity, we need to take our test instruments to a place where there is no gravity or little gravity. In other words we should go to outer space. Since we cannot go to outer space, we came up with an alternate solution that will simulate a low gravity situation.

For example, we can do our test on a roller coaster. When a roller coaster is going down and we are going down with it, that is a simulation of near zero gravity. (Actually, gravity is everywhere. The fact that astronauts feel zero gravity is that they are constantly falling just like a roller coaster.) Also, when the roller coaster is going up, that simulates extra gravity. Your setup must be very small so you can take it with you on a roller coaster. If the gravity be a factor, when the roller coaster is coming down, the manometer must show less pressure than when it is going up.

I did this experiment and made a small setup, but instead of testing it on a roller coaster, I decided to hold it in my hands and quickly sit or quickly stand and see the results. Surprisingly, there was no change of pressure shown in my manometer while sitting or standing. So what do you think? What was the problem?

By looking at my manometer setup, I noticed that my manometer by itself is working based on the pressure of the liquid inside of it. Therefore, when the pressure drops, it drops both in my manometer and in my test liquid. That’s why they stay in balance. So for this test we need a manometer that does not work based on liquid pressure. We will not do this at this time because we do not have a manometer that does not use water pressure, and because the answer to this question can be concluded from our first experiment.

Materials and Equipment:

List of material can be extracted from the experiment section. The following is a partial list:

• A quart jar full of water
• Several two liter “pop bottles” and assorted plastic bottles
• Several “push pins” for making holes
• A medicine dropper for the cartesian diver
• A large clear funnel with a stand for holding it in place
• Several plastic straws and a supply of strong plastic tape or Duck Tape

Results of Experiment (Observation):

Write the results of your experiments as you perform the tests.

Summary of Results:

Water has weight, as anyone who has lifted a bucket of water knows. The pressure in the ocean, or any body of water, is proportionate to the depth below the surface. At the great depths of underwater exploration the pressure may be tremendous and any underwater vehicle, like a submarine, must be very strong in order to withstand the weight of the water.

Write more, this is just a start…

Conclusion:

What did you learn from your experiments? What are the answers to all of your questions about water pressure?

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

List of References

http://www.seagrant.wisc.edu/madisonjason11/experiment_pressure.html

http://www.wwp.org/dockom/experiments.asp

http://www.mste.uiuc.edu/murphy/WaterTower/default.html

Additional experiments and information

What is pressure and how does it affect divers?

The depth at which Aquarius scientists work means they’re under quite a bit of pressure, pressure exerted by water. This series of explorations will take you through something that all of us deal with, but is especially important to underwater divers – pressure .

DOES WATER SEEK ITS OWN LEVEL?

Purpose: a trick to challenge the students., description:.

The liquid level in the left side of the U-tube is higher than that in the right side of the U-tube. How does one explain this?

Two immiscible fluids of different densities, which are identical in physical appearance, are in the two ends of the U-tube. The point where they meet (which could be easily seen) is covered by the clamp which holds the U-tube.

PASCAL’S LAW – COILED TUBE PARADOX

PURPOSE : To illustrate Pascal’s law in a dramatic way.

Referring to the photograph on the right, pouring water (colored green) into the tube at the left in the photograph causes the asymmetric configuration shown due to the equalization of pressure in the central air bubble. Similarly, if one end of a three-turn loop of tubing is raised vertically, as in the photograph at the left above, water poured into the high end will never come out the bottom end, even when the bottom end is lying flat on the table, as seen in the center photograph.

It is always important for students, parents and teachers to know a good source for science related equipment and supplies they need for their science activities. Please note that many online stores for science supplies are managed by MiniScience.

Testimonials

" I called School Time and my husband and son came with me for the tour. We felt the magic immediately."

- Robby Robinson

" My husband and son came with me for the tour. We felt the magic immediately."

- Zoe Ranson

Contact Info

Our address, working hours.

Week Days: 07:00-19:00

Saturday: 09:00-15:00

Sunday: Closed

Science Project

Relationship Between Depth and Pressure Review and Equations

Fluid Flow Table of Contents Hydraulic and Pneumatic Knowledge

Anyone who dives under the surface of the water notices that the pressure on his eardrums at a depth of even a few feet is noticeably greater than atmospheric pressure. Careful measurements show that the pressure of a liquid is directly proportional to the depth, and for a given depth the liquid exerts the same pressure in all directions.

As shown in Figure 1 the pressure at different levels in the tank varies and this causes the fluid to leave the tank at varying velocities. Pressure was defined to be force per unit area. In the case of this tank, the force is due to the weight of the water above the point where the pressure is being determined.

The volume is equal to the cross-sectional area times the height (h) of liquid. Substituting this in to the above equation yields:

This equation tells us that the pressure exerted by a column of water is directly proportional to the height of the column and the density of the water and is independent of the cross-sectional area of the column. The pressure thirty feet below the surface of a one inch diameter standpipe is the same as the pressure thirty feet below the surface of a large lake.

If the tank in Figure 1 is filled with water that has a density of 62.4 lbm/ft3, calculate the pressures at depths of 10, 20, and 30 feet.

A cylindrical water tank 40 ft high and 20 ft in diameter is filled with water that has a density of 61.9 lbm/ft3.

(a) What is the water pressure on the bottom of the tank?

(b) What is the average force on the bottom?

Link to this Webpage :

Copy Text to clipboard

© Copyright 2000 - 2024, by Engineers Edge, LLC www.engineersedge.com All rights reserved Disclaimer | Feedback Advertising | Contact

Science Projects for All Ages

Water Pressure and Depth

Have you ever watched scuba divers on tv? They face many challenges when they dive. The deeper that a scuba diver descends, the more dangerous the dive becomes. During a dive, divers can experience lots of different problems. Some of these problems can be lightheadedness, joint pain, coordination loss, and even paralysis. Why? The answer to that question has to do with air, gas, and even pressure. Did you know that water pressure is much more dense than air pressure? In this experiment, you’re going to observe how pressure changes with depth.

What You’ll Need:

Scissors Sharpie (marker) Duct tape 1 clear 2-liter bottle with lid Water Ruler 3 in. nail with a sharp point An adult to help

Directions:

1. With the scissors; remove the label from the bottle so that you can observe what happens within the bottle. 2. Using the ruler and marker; make a mark on the bottle that’s 3 inches from the bottom of the bottle. 3. Make another mark that is 8 inches from the bottom of the bottle. Do this directly above the first mark that you made. 4. With the cap still on the bottle, lay the bottle down on a flat surface. Your bottle should now be horizontal. 5. Have an adult use the sharp nail to poke a hole into the two marks that you made on the bottle. 6. Using your duct tape, put a small piece of tape over the holes that were made to cover them. 7. Fill the bottle, clear to the top, with water. 8. You can either set the bottle at the side of the sink with the holes facing toward the sink or you can take it outside for this next part. 9. Quickly remove the tape from both holes and watch what happens! 10. What is your observation?

Conclusion: When the tape is removed, water will shoot out of both of the holes. The bottom hole has the water exiting the bottle more forcefully. Why? The bottom hole is deeper under the water and therefore under greater pressure. There is more weight pressing down on the bottom so it makes the water exit with more force.

A Step Further:

For a full experiment and project, make other holes at different depths in the bottle. Test to see if the water pressure increases at a steady rate the closer the holes are to the bottom. Try using a wider container. Discover whether or not more water matters or if depth is what matters most. You can also use salt water vs. regular water. Salt water weighs more than regular water.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Liquids Science Experiment: Water Pressure

Find out how depth affects water pressure.

A Liquids Experiment about Water Pressure

What you will need:.

• Empty plastic bottle
• A pair of compasses

What you will do:

• Use the compass to push a hole in the side of the bottle close to the bottom.  Be very careful – it’s sharp!
• Now push another hole about halfway up the bottle, in line with the first hole.
• Finally push another hole in line with the first 2 but close to the top.
• Outside, fill the bottle right to the top then put it down on the ground.
• Observe how the water leaks out of the bottle.  What do you notice about the different holes?

What is going on?

Air pressure pushes down on the surface of the water all the time, so water is always under a certain amount of pressure.  However water itself is also heavy, so water at the top of the bottle pushes down on water at the bottom of the bottle, increasing the pressure.

Monster Challenges: 

• Use spare bottles to have a competition – who can make their bottle spurt water the furthest? What can variables can you change to make the water go further?
• Next time you are swimming, try picking up a Frisbee or other flat object from the bottom of the shallow end of the pool. Now try it at the deep end – how is it different?
• Can you design a machine that uses water pressure to run?
• Research the adaptations fish living in the deep parts of the ocean have made to cope with the water pressure there.

Teaching Notes:      Monster  Sciences Experiment: Liquids LQ12

Key concepts:.

The effect of water pressure

• Investigation Record IR01– one copy per student
• Experiment Description Liquids LQ12– one copy per student
• Empty plastic bottle, pair of compasses, water

Lesson Notes:

This experiment must be done outside – it makes a mess!

For younger students I usually put the holes in the bottles myself.  For all other students safety is key – show students how to hold, carry and use the pair of compasses safely before giving any students access to them.

As a class discuss the experiment prior to undertaking it and students should complete the sections of their Investigation Report IR01 from ”Title to “Hypothesis”.

What should happen in this experiment, and why?

The water flowing from the lowest hole should spurt the furthest as it is under the most pressure.  The highest hole should show the least pressure.  As the water level in the bottle decreases, so should the flow rate from each of the holes, but the proportions should remain the same.

Follow up discussion questions:

• If you were using water pressure to run water to your house, where would you think the best place to put the water tank would be?
• Where should the hose attach to the tank?

Get this experiment here or as part of a bundle of Experiments about Liquids  here .

Written by admin

View all posts by: admin