Balloon-powered Hovercraft

Repurpose those old CDs and water bottle caps into a working hovercraft!

Vocabulary

1. Friction–(noun) the rubbing of one thing against another
2. Hovercraft–
   (noun) a vehicle supported above the surface of land or water by a cushion of air produced by fans blowing downward

Newton’s First Law states that an object in motion will stay in motion unless acted upon by an outside force.

Newton’s Second Law tells us that Force = Mass * Acceleration. In other words, an object’s mass, multiplied by its amount of change in position gives us the amount of force that it can expend on another object.

Newton’s Third Law states that for every action there is an equal and opposite reaction.

Materials

• Old CD (cardboard cut into a circle/square with a hole in the center will work as well)
• Superglue or hot glue
• Pop-up lid from a drink bottle (must have a valve)
• Balloon

Activity

1. Apply glue to the base of the drink lid. Use a good amount as you are trying to make an air-tight seal.
2. Press the lid to the center of the CD over the hole and allow to dry.
3. Place the balloon over the drink lid opening and attempt to push it across the floor.
   • Take note on the distance traveled and measure how far the hovercraft traveled with a single push.
4. Remove the balloon and blow it up. Twist the opening to keep the air in. (A clip can be used to help hold the twist in place.)
5. Place the balloon back over the drink lid opening, being sure the air remains in the balloon.
   • Make a prediction of how far the hovercraft will travel when moving on a layer of air.
6. Remove the clip to allow the air to escape from the balloon and watch it go!
   • Measure how far the balloon traveled. Explain why it moved differently.

Further Exploration

• Experiment on different surfaces, including water.
• Try adding weights to the hovercraft and observe the results.
• Try different sizes of balloons. Does one size work best?

Explanation

Friction is a force that acts in an opposite direction to movement. Friction is found everywhere that objects come into contact with each other. The force acts in the opposite direction to the way an object wants to slide. In general, the rougher a surface, the more friction there is when moving an object across it.

Real hovercrafts use fans to pump air underneath themselves allowing them to travel over land and water on a layer of air. This balloon hovercraft reduces friction by blowing the air from the balloon between the CD and surface, making it move much quicker across the tabletop or floor.