2. PING PONG BALLS
Anyone who’s watched the top table tennis players in action knows they hit the ball hard and that it travels almost too quickly for the eye to see. But even that pales in comparison to the air-powered cannon built in 2013 by students at Indiana’s Purdue University, which fired ping pong balls at more than 900 mph. “You can get really, really high accelerations, the ball comes out of the barrel intact and doesn’t break until it actually hits something,” mechanical engineer Mark French Inside Science. The cannon used a vacuum pump to suck the air from a sealed tube, the air rushed to a nozzle shaped like an hour glass, and the nozzle propelled the ping pong balls at supersonic speed—about 919 mph. Remarkably, given their light weight and poor aerodynamics, the ping pong balls delivered as much energy to their target as a brick falling several stories.
via Mental Floss
