Type of Activity: Physics

Materials Needed:


- A group of similar coins (Five one-pound coins)

- A plastic knife.

Duration: 15 minutes

Applications: The reaction of passengers in a bus when it suddenly stops or moves. Wearing seat belts. Why we wear a seat belt.

Target Group: 12-14 years old

Steps of the Experiment:

1. Align the coins in a vertical, regular line.
2. Use the plastic knife to move the lower coin without touching the other coins.

What is Happening?

The coin you pushed will move, while the rest of the coins will remain in their places. 


Because of the heaviness of these coins, they remain in a state of inertia, so, they do not move when we push the lower coin. Since the lower coin is light, its inertia is much less than that of the whole pile. Therefore, it easily moves when we push it.

Relevant Experiments:

 “The cup and the coin”.


You can use setscrews instead of metal coins.


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