Snapshot - Newton's Cradle

My roommate bought a Newton's Cradle a few weeks ago, and every time we are sitting on the couch, we can't help but lean over to the coffee table and make the balls swing back and forth. She was bummed when she realized that the swinging eventually stopped; movies had deceived her into believing they exhibited perpetual motion. Despite this setback, it's still addictive to watch the wonder of simple physics. As it says on the box, "it's art in motion".