How to do an Air Pressure on Water Experiment for Kids

We’re going to show you how the air pressure on water experiment works. It may surprise you! But it illustrates the effect of atmospheric pressure on liquids.

Have you ever wondered how water can be pulled up into a straw? Or what happens to the air pressure when you go up in an airplane?

Now, you can explore these questions with this awesome experiment. The science behind this phenomenon is air pressure.

If you have ever had a bike pump, then you know that the higher the pressure inside, the more forcefully it can push air out. This same principle also applies to water being sucked up through your water dispenser.

Air Pressure Experiment For Kids Science Activities

Air Pressure and Water Experiment Supplies

Air Pressure on Water Experiment is an awesome physical science experiment as it can be done using simple and easily available supplies. Here is the list of items you need to collect before you start the experiment.

Materials Required

1) A Balloon

2) A Plastic straw

3) Water

4) A small container (glass one is better to get a good visual experience) or a Peg

5) Putty or Plasticine

6) A Plastic water bottle (Make sure it is clean and clear no matter the shape and size.)

7) Food Color

8) Some other miscellaneous things like kids-friendly knife, glue, metal scale, etc.

Directions to do Air Pressure on Water Experiment

Step-1: Select a place where you feel free to do experiments with water like sinks or outdoors as this activity messy up things with water.

Put Hole In Bottle

Step-2: Now, pick an old and clear plastic bottle and make a hole of 10cm at the middle of the bottle. You can use kid-friendly knife or scissors to make hole. Whatever the tool you use, make sure you are moving it clock and anti-clock wise direction to achieve a good round shape. You can also use a soldering rod to make exact size hole as of straw.

Close Hole Using Glue Gun

Step-3: Once the hole is ready, insert the plastic straw into it and seal any leakages around the hole using hot glue. You can also use putty or plasticine to seal it.

Insert Straw To Bottle

Step-4: Then, take a small container and add some amount of water. Also add a few drops of food color and into the water to make it colourful. This colourful water is good to experiment with as it gives good visual experience of the experiment.

Attach Angry Bird To Straw
Fill Bottle With Color Water

Step-5: As a next step, pour the color water into the plastic bottle fixed with straw up to half way. And keep a peg or small glass or transparent container under the other end of the straw which is hanging outside of the bottle.  

Step-6: In this step, take a medium sized balloon and inflate it using your mouth or any balloon blower machine. Seal the mouth of the inflated balloon and fit it around the mouth of the bottle carefully. At this point, our school science fair project set up to show Air Pressure is ready for demo.

Blow The Balloon

Step-7: Now, release the secured mouth part of inflated balloon such that the air inside it goes straight down into the plastic bottle.

Step-8: You will notice the color water inside the plastic bottle moving out of the straw towards the small container placed beside the plastic bottle under the open end of straw.

Air Pressure Science Experiments for Kids

What is the science behind the water movement in this experiment?

In this physical science project, the air gives pressure equally on the water and inside straw when there is no balloon around the mouth of the plastic bottle.

But when the inflated balloon is set up on top of the plastic bottle i.e. around its mouth part, the air inside the balloon forces down into it.

Thus, creates increased pressure on the surface of the water and presses the water molecules down due to force and gravity. This increased pressure inside the water pushes water into the straw. And hence the water moves towards the straw and stores in the small container placed outside.

The science concepts learned through this classic Air Pressure Experiment on Water include:

1) Atmospheric Pressure: The pressure applied by the molecules (that has weight) present in the atmosphere or air towards the surface of the Earth due to the force and gravity is known as Atmospheric Pressure. Atmospheric Pressure is also known as Barometric Pressure.

2) Pressure: The amount of force exerted per unit area byt the surrounding surfaces and particles is known as pressure. The pressure unit is pascal. The formula of pressure is P=F/A. Absolute pressure, atmospheric pressure are the types of pressure.

3) Potential Energy: The energy developed due to the pressure or force with in itself is known as potential energy. Potential energy can also use electric charges to build its energy.

In this experiment, the air inside the inflated balloon develops potential energy and tries to come out of it. And hence, the water feels pressure when the mouth of the inflated balloon releases.

This pressure makes the water flow out of the plastic bottle and into the small container placed beside it through the straw.

Other Air Pressure Experiments You Can Try at Home

Balloon and Pin Experiment

Egg in a Bottle – Air Pressure Experiment

Balloon in a Bottle : Air Pressure Experiment

Drip Drop Bottle-Water Bottle Pressure Experiment

What we learn from Air Pressure on Water Experiment

  • Students learn about Air and Atmospheric pressure
  • Explore different types of forces, pressures, and potential energy
  • Get knowledge on various science terms such as atmospheric pressure, force, pressure, stress, etc.
  • Can be a great science fair idea
  • Encourages children to actively participate in science work-shops and events

How do you define Air Pressure?

Air pressure is the pressure created by the weight of the particles in the air that are forcing to move down to Earth because of gravity.

In simple words, air around us encompasses of a lot of air molecules (that has weight), which exerts pressure whenever they get in touch of any objects. This is the pressure we call it as Air Pressure.

Air pressure is also known as Atmospheric Pressure. As we use Barometer to generally measure atmospheric pressure, we also call it as Barometric Pressure.

The standard unit of atmospheric pressure is equivalent to 101,325 Pa or 29.9212 inches Hg or 760 mm Hg or 14.696 psi.


P_h= P_0 e^{\frac {-mgh}{kT}}

P_0= sea level pressure

P_h= pressure at height h

g= Acceleration due to gravity

K= Boltzmann’s Constant (Ideal gas constant divided by Avogadro’s number)

T= Absolute Temperature

M= Mass of one air molecule

Safety Measures

1) It is highly recommended to wear safety glasses to protect your eyes.

2) Handle the hot glue or hot melting glue carefully otherwise children may burn their hands

3) Use kid-friendly knife

4) Always there must be an adult supervision while conducting this experiment


How to explain air pressure on water experiment?

When you inflate the balloon, the air inside it creates potential energy and faces pressure against the rubber surface of balloon. And when the inflated balloon placed over the neck of the plastic bottle, the air pressure of balloon flows into it.
This creates higher pressure on the top of the plastic bottle and thus creates even more pressure inside water in the bottle. This pressure moves water from the plastic bottle to the container placed beside it through the straw.

How do you demonstrate pressure?

There are many ways to demonstrate pressure through our daily activities. Here is the easy one to explore or demonstrate pressure:
1) Take a plastic water bottle and fill it with water to its half way.
2) Place a straw into its neck part and seal the leaky edges using putty or clay.
3) Blow heavily into the straw which creates increased air pressure inside the bottle.
4) This increased pressure inside the bottle pushes the water out of straw like a fountain.

What is the science behind water dispenser?

Water dispenser plays important role in restaurants, hotels, offices, etc. And it is the perfect example to demonstrate Air Pressure.

Water dispenser is useful to supply normal to moderate to hot water whenever we press button. Water dispenser is a set-up of upside down 4-5 gallon water bottle at the top of the machine.

Mostly, water dispensers work by pressing button, through which you are increasing the pressure inside by allowing the air inside the bottle. And that’s the way, you can dispense water from the machine when air allowed inside the bottle.

What happens when air exerts pressure on our body?

Air has mass as it contains a lot of tiny particles that possess weight. These particles when touched against any solid object, exerts pressure.

The pressure exerted by air molecules in all directions around us, known as air pressure. However, because of the air particles weight, we experience more air pressure when we stay closer to the surface of Earth.

How do you make an air into a bottle with balloons and straws?

Take one litre plastic bottle and make a straw size hole at the middle of it. Insert a straw through the hole and seal the leakages using clay or putty. Outside the bottle and under the other open end of the straw, place a small container.

Now, fill half of the bottle with water and cover its mouth using inflated balloon. When you release the air inside the balloon, there creates high pressure inside the bottle and water.

Thus, the water is let outside the bottle through the straw and into the container placed beside the bottle.

How do we use air pressure in everyday life? (Give examples).

Here are some of the situations where we use air pressure in everyday life:

1) When we drink through straw, the air pressure inside it decreases while outside pressure increases and forces the drink to suck inside the straw.

2) Consider a vacuum cleaner, it has a fan inside it which creates low pressure environment inside the machine. Whereas the outside atmospheric pressure forced inside and takes the dirt and air molecules to suck inside the machine.

3) Syringes creates pressure by plunging the nob of it while taking the blood from human body. This pressure sucks the blood from human body into the syringe easily.

What are some examples of air pressure?

1) The pressure of air inside car tires holds the car weight
2) The flight movement up in the sky because of the air pressure on its wings.
3) Bullet firing from the gun using gas pressure.
4) Inflation of balloon because of air pressure developed inside.
5) Sucking a drink through straw using pressure created inside it.

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