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 🚗💨

Science Behind It

This project combines stored energy and thrust.

🔋 Stored Energy (Elastic Potential Energy)

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

🔄 Energy Conversion

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

💨 Thrust & Motion

The spinning propeller pushes air backward.

👉 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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