The Coin and Paper Challenge
Introduction:
Einstein built huge ideas on top of simple truths about motion. One of the most important truths is inertia. Inertia is an object’s tendency to keep doing what it is already doing, staying still or moving, unless something forces it to change.
This quick activity shows inertia in a way students can see and repeat.
What You Will Need:
One clear drinking glass
One index card or small piece of paper
One coin
A flat table
Notebook and pencil
Step-by-Step Instructions:
Place the glass on the table.
Put the index card on top of the glass opening.
Place the coin on the center of the card.
Flick the card sharply sideways with one quick motion.
Observe what happens to the coin.
Repeat three times, trying a slow pull and then a fast flick.
What to Look For:
Does the coin drop straight down when the card moves quickly?
What happens when the card moves slowly?
Which motion changes the coin’s movement more, slow or fast?
Fun Fact:
Inertia is part of why seat belts matter. Your body wants to keep moving when a car stops suddenly.
Safety Tip:
Use a stable table and keep glass away from the edge. If you prefer, use a plastic cup instead.
Journaling Prompt:
Explain why the coin falls into the glass when the card is flicked quickly. Use the word inertia in your explanation.