Monday, April 11, 2011
Hello girls! This Monday's project is as easy as it is fun. I hope Spring is in full bloom where you are, because this is a great project to do outside--but it can be really fun inside as well, especially with ricocheting (flying into something and bouncing off in a crazy new direction). Has that piqued your interest?
We're going to use a tennis ball and a basketball to demonstrate the power of momentum. You don't need adult supervision for this one--but you will want permission before you do it inside!
If you don't have a basketball, that's okay--you can use any big, bouncy ball, like a red playground ball. You can also use any small bouncy ball instead of a tennis ball, like a ping-pong ball.
First, hold both balls straight out in front of you, and drop them at the same time. Hey, you might ask, where's that ricocheting you promised? Don't worry, it's coming--this was just to show how high the balls normally bounce, without an extra boost from momentum.
Now we use a little bit of momentum. Hold the basketball right on top of the tennis ball, and release them at exactly the same time. What happened? Did the tennis ball not bounce at all, while the basketball bounced a little higher than where you first dropped it? That happened because instead of bouncing itself up, the tennis ball transfered (gave) all of its momentum to the basketball, and the basketball bounced higher because of the extra momentum from the tennis ball.
What do you think will happen if you drop them with the tennis ball on top of the basketball? Try it out--but you might want to tell anybody watching to duck first!
Whoa there! Not exactly the same, was it? The tennis ball shot off and went way higher! But why? Actually, the same thing happened as before--the ball on the bottom gave its momentum to the ball on the top. But momentum is tricky. The faster something is going, the more momentum it has--but it also has more momentum the bigger something is. Since the basketball is so much bigger than the tennis ball, adding the tennis ball's momentum to the basketball only makes it go a little higher. But adding the basketball's momentum to the tennis ball makes it shoot off, going as much as nine time higher than it did before! Try getting somebody really tall to do this--then the tennis ball will really soar!