demonstrations:two_falling_coins

Two Falling Coins - Projectile Motion

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

Categories: Motion

Alternative titles: Projectile Motion

Summary

Two coins are released from the same height: one falls straight down while the other is given a horizontal push. Both hit the ground simultaneously, demonstrating that horizontal velocity does not affect vertical motion.

Procedure

  1. Place a ruler so that it extends over the edge of a table.
  2. Position one coin on the ruler at the overhanging end and place a second coin directly next to it on the table edge.
  3. Flick the ruler so that the first coin drops straight down while the second is pushed off horizontally.
  4. Observe and listen for when the coins strike the floor.

Simple Projectile Motion Demonstration - Alom Shaha:


Projectile motion demo with two coins - Simon Lloyd:


📄 Two falling coins - Sciensation: https://sciensation.org/hands-on_experiments/e5060p_fallingCoins.html

Variations

  • Try using different small objects instead of coins to confirm the result.
  • Change the table height to see how the fall time varies while both still land together.
  • Use slow-motion video to track the different paths of the two coins.

Safety Precautions

  • Ensure the area below the table is clear to prevent coins from hitting people.
  • Do not use heavy or sharp objects in place of coins.
  • Be cautious when flicking the ruler to avoid hitting your hand.

Questions to Consider

  • Which coin is faster, and why?
  • Why do the two coins hit the floor at the same time?
  • Does gravity affect vertical and horizontal motions differently?
  • What does this experiment reveal about velocity as a vector quantity?