Apparatus Inertia

For illustrating an effect of inertia.

When you place the ball on the card and pull back the spring the card (cloth) shoots forward but the ball (dish) drops back to post (table). Actually the ball did move but because it is a ball -it settled into the cup. (The ball has a 5 mm flat spot which permits to stay on the card)

Try the same experiment with a coin. Contains : glass ball, card, plastic base, post hardware instructions.