I love playing ping pong, but I always, ALWAYS dent the tiny plastic balls. I was playing ping pong with my friend after school today, and I dented yet another ball. I was grumbling that I would have to go out and buy new ones, when she showed me how to make them round again. All you have to do is put the balls in a bucket of warm water. I know, I thought she was crazy when she first told me too. But, it actually works! Maybe if I explain the science behind it, you’ll believe me.
A brilliant French scientist named Jacques Charles figured out that if, while the pressure on the gas is the same, the temperature increases, the gas will expand. If the temperature decreases, the gas will take up less space. Naturally, this law is called Charles’s Law. Now you think I’ve totally lost it. Why am I talking about a science law when I’m supposed to be admitting that the ping pong trick doesn’t actually work? Actually, the two things are completely related. When you put the dented ping pong ball in warm water, the temperature of the gas increases because the water on the outside is heating the gas (or air) inside. Charles's law states that when a gas’ temperature is increased, it will take up more space. The pressure has to remain constant, or course. In the ping pong ball situation, as the air inside the ping pong ball heats up, it expands to take up more space, according to Charles’s Law. Because it has to take up more space, it has to force the dented plastic of the ball out to create space inside, and makes the ball round again. See, I’m not crazy! Try it and see for yourself!