demonstrations:inertia_hat

Inertia Hat

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★★☆ Can be done by science teachers
Safety: ★☆☆ Minimal safety procedures required

Categories: Motion

Alternative titles: Newton's Inertia Hat

Summary

A wire coat hanger is shaped into a headpiece holding two tennis balls. When balanced on the head, the ball remain still when the person turns.

Procedure

- Use wire cutters to remove the hook from a wire coat hanger.

  1. Bend the hanger into the shape of the letter “M,” ensuring the center point of the “M” is sharp and well-defined.
  2. Slightly bend the bottom ends of the “M” upward so they can hold zip ties securely.
  3. Tape a tennis ball to each end of the “M,” ensuring both balls are the same size and hang below the center point.
  4. Place the point of the “M” on the top center of your head to balance the hat.
  5. Spin yourself around while keeping the tennis balls still, or spin the tennis balls around your head while you remain still.
  6. Observe how inertia keeps the tennis balls in place until friction or another force slows them down.

Inertia Hat (Newton's 1st law) - Kids Fun Science:


📄 Inertia Hat - Morning Science: https://www.astronaut.org/wp-content/uploads/WABI-segment_Challenger_October-10-2016.pdf

Variations

  • Try spinning at different speeds to see how long the balls stay still or in motion.
  • Use lightweight balls of different sizes to compare inertia.
  • Balance the hat on a smooth surface (like a bottle) instead of your head to reduce friction and prolong motion.

Safety Precautions

  • Use caution with wire cutters to avoid injury.
  • Ensure wire ends are smooth or taped to prevent scratching the head.
  • Spin slowly to avoid dizziness or loss of balance.
  • Use lightweight objects like tennis balls instead of harder items.

Questions to Consider

  • Why do the tennis balls stay at rest even when you spin your body?
  • What eventually causes the balls to stop spinning?
  • How does this model show Newton’s First Law of Motion (inertia)?
  • How does friction between the wire and your head affect the demonstration?