Now then, Newton came up with three really important Laws of Motion that tell us the basics of how things move. Let me show you the first one.
Lazy Tennis Ball Trick
What you need:
- Small board or piece of stiff paper
- Toilet paper roll tube
- Tennis ball
- jar of water
What you do:
- Lay a small board or piece of stiff paper on a jar of water.
- Place a toilet paper roll tube upright on the board, and on this place a tennis ball.
- Now try to get the tennis ball into the jar of water without touching it. Can you do it?
- Try pulling the board sharply to the side. The board will be moved out of the way, but the ball falls straight down!
What happened?
Because of its weight, the tennis ball has a property called inertia. This means that if it isn’t moving, it wants to stay still. Even though the board is pulled sideways, nothing is pushing or pulling on the ball (besides gravity, of course), so the ball simply drops into the jar. Cool, huh?
Everything in the world is made of stuff, which scientists like to call mass. And the more stuff there is in an object, the heavier something is here on Earth, and the more inertia it has. So heavy things have more inertia: it’s harder to get a heavy object moving than to get a light object moving.
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