Gravity is a force that acts on us every day. Let’s see what fun we can have with the force of gravity and with inertia.
First of all, see if you can find out the meaning of inertia. What does it mean when the explanation of inertia says something will not move unless a force acts on it? What do you think it means when it says something will stay in motion unless a force acts on it?
Get some checkers from a checkers game. Stack eight of them on a table or desk on top of each other so you have a small tower of checkers (if they are the kind that lock together, set them so they do not stick together). Take a ruler and set it on the table next to the stack of checkers. Push the ruler in a quick, hard motion so it hits the bottom checker, hard. What happened to the stack of checkers? What does this have to do with inertia?
Open a paperclip into an S-shaped hook. Tie the paperclip on the end of a string. Hang the string from a yardstick or meter stick set across two pieces of furniture so it can swing like a pendulum. Put some washers or a bunch of paperclips on the hook so it feels heavy.
Now, stand an empty bottle up near the pendulum. Bring the weight back until it almost touches the empty bottle. Let go. Does the pendulum swing back and knock the bottle down? Why?
Take Me to the Ball Game
Some friends who had been learning about inertia and gravity invented their own games. They made a target on paper with a circle in the center marked 10 points, a larger circle around it marked 5 points and a bigger circle around that marked 3 points. Then they made a ramp from cardboard.
For their first game they rolled a golf ball down the ramp and tried to have it stop in the circle to get points. In the game, you were allowed to change how steep the ramp was but the ball had to start at the top of the ramp and the distance to the target couldn’t change. They played until one of them scored 50 points.
Their next game was to keep the ramp the same each time but try different balls to see who could score the most points. They tried a golf ball, a tennis ball, a billiard ball, a baseball and a softball. Different balls went different distances. They changed the game after a while so that the surface the ball rolled on was different, but just used a tennis ball. They tried sand paper squares, newspapers, a bath towel. Some surfaces made the tennis ball roll farther, some didn’t.
Their third game was to have a ball role down the ramp and push a cup into the target circles to score points. They tried a paper cup, a Styrofoam cup and an unbreakable plastic mug. Later they changed the game by taking the target away. They set the ramp up on a table top and tried to roll the ball down the ramp so that it pushed a cup to the edge of the table so it almost fell off. If it fell, there was no score. If it stayed hanging over the edge, there was a score of 6 points, like football.
Try some of these games. Have fun.