Education:Science Projects: It Won't Budge

What you need

What you do

1. Place the cup on a flat surface with the card on top covering the opening.
2. Lay the coin in the middle of the card. Your goal is to get the coin in the cup without touching the coin. Can you think of a way to do it?
3. Now use your forefinger and flick the edge of the card to move it straight ahead away from you. What happens? Did you meet the goal?

Why this happens

Have you ever heard of inertia? It's a property of physics, which says that an object at rest will tend to stay at rest. That's why the coin fell into the cup—its inertia kept it from moving with the card, and gravity pulled it down. But did you flick the card too slowly? Then this experiment didn't work, because friction keeps the coin in contact with the slow-moving card, so the coin goes with the card. Try flicking the card quickly and see if it works now.