Build a rubber band powered propeller car and discover how stored energy turns into motion. This exciting STEM activity shows how twisting a rubber band stores energy, which spins a fan to create thrust and move the car forward.

Difficulty Level: Medium

Concepts: Thrust and Reaction, Laws of Motion, Elastic Potential Energy, Kinetic Energy

Materials List

  • Cardboard base or foam board
  • 4 bottle caps or plastic lids (wheels)
  • 2 wooden skewers (axles)
  • Straw pieces (for axle holders)
  • Rubber band
  • Ice cream sticks (for frame)
  • Small plastic propeller (or DIY from plastic/paper)
  • Toothpick or stick (to hold propeller)
  • Glue (hot glue recommended with supervision)
  • Tape

Steps

  1. Build the base
    • Cut a rectangle from cardboard or foam board for your car.
  2. Attach wheels
    • Insert skewers through straw pieces and fix them under the base. Attach bottle caps as wheels.
  3. Create the frame
    • Use ice cream sticks to build a raised frame to hold the propeller.
  4. Add the propeller system
    • Fix a stick or axle at the front and attach the propeller to it.
  5. Attach the rubber band
    • Tie one end of the rubber band to the propeller shaft and the other end to the back of the car.
  6. Wind it up
    • Rotate the propeller to twist the rubber band and store energy.
  7. Release and watch!
    • Place the car down and let go - the spinning propeller will push air backward and move the car forward πŸš—πŸ’¨

Science Behind It

This project combines stored energy and thrust.

πŸ”‹ Stored Energy (Elastic Potential Energy)

When you twist the rubber band, you store energy inside it. This is called elastic potential energy.

πŸ”„ Energy Conversion

When released, the rubber band untwists and turns this stored energy into motion, spinning the propeller.

πŸ’¨ Thrust & Motion

The spinning propeller pushes air backward.

πŸ‘‰ Just like rockets and airplanes:
Air pushed backward = car moves forward

This is again explained by Newton’s Third Law of Motion:

Every action has an equal and opposite reaction.

Watch the video!

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