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