Challenge!
Your friend has a loonie sitting in the middle of the open palm of his hand. He says you can have the loonie if you can grab it out of his hand before he can pull away his hand. Can you do it?
Think Physics!
It is tempting to simply reach for the coin and try to grab it with your fingers. A faster way is to place your open hand above his, and quickly drop your hand down on his hand. The coin will tend to remain where it is (INERTIA!), so for a brief time it is in ‘mid-air’, in your own hand, and you can grab it!