Playing with Gravity

What You Need:

• Small watermelon
• Apple
• Really tall playground structure

What You Do:

1. Before both of your scramble onto the playground structure, sit down with your child. Take turns weighing the watermelon and apple in your hands. Does she know which one is heavier?
2. Ask your child to imagine both the watermelon and the apple falling from the tallest point of the playground structure. Which fruit does she think will fall faster. Most people—not just children—think that heavier objects fall faster than lighter ones.
3. Climb with your child to the tallest point of the play structure. Make sure she doesn't go higher than the structure is actually intended to be climbed.
4. Hand her the apple and you keep the watermelon.
5. Drop both fruits at the same time. Which one hit the ground first? (Hint: if this experiment is done correctly, both watermelon and apple will smack the ground at the same time. If the heavier object hits first, you'll need to drop the fruit from a higher point)
6. Is your child surprised? How can both the big, bulky watermelon and the tiny apple fall at the same speed?
7. Explain gravity's pull. The same force that keeps you and her stuck to the earth pulls the watermelon and the apple to the ground. Gravity doesn't have a stronger pull on heavier objects; the pull is equal. That's why all objects fall at the same rate. It wouldn't matter if you dropped a big bowling ball and a ping pong ball—they would both hit the ground at the same time if dropped from a high enough point. Your kid might be temped to challenge this law of physics. How about a bowling ball and a piece of paper? It's true that the bowling ball would reach the ground first, but that's because of a pesky variable: air resistance. Explain to your curious kid that, believe it or not, the piece of paper and the bowling ball would fall at the same rate in a vacuum!