This video of a combination of liquid nitrogen, a plastic drinks bottle, some water, and 1,500 ping pong balls shows yet again that besides being amazingly helpful, science can also be really fun.
http://www.youtube.com/watch?feature=player_embedded&v=dfiR1Rde7dI
Happy Friday!
Discussion
4 Thoughts on "I Wish I'd Had This Teacher — The Ping Pong Ball Explosion"
Why did the trash bin itself launch upwards when the bottle exploded? Anybody know?
Equal and opposite reaction, I think — the force of the explosion was looking to go everywhere, and part of it went downward, forcing the bottom of the can down, as well as the floor, and those both then rebounded. If you look at the slow-motion shot from the end of the room, the floor flexes, which bounces the can up. The bottom of the can also probably provided some spring action as it recoiled after being forced down. There are probably couple of other smaller contributors (partial vacuum above from rush of air up and out, the ping pong balls might be jostling the can up a bit as they evacuate), but I think the floor and can bottom flexes would be the biggest contributors.
I hope my answer isn’t totally stupid, but another comment will surely let me know.
Thanks, Kent. Since this was a classroom demonstration, there should have been some discussion of the physics of the event. I think we do a disservice to STEM teaching when we act like science is only fun when it is merely fun and not instructional.
Great entertainment, but a bit scary on the safety front. He should have had a full face protection mask, and have worn gloves and arm cover all the way through. Why did he take the safety gloves off after he had filled the bottle?
