## Fast Fall

Do heavy objects fall faster than light objects? Background:

Gravity is a force, or type of energy, that pulls all objects toward Earth. It holds people on the ground and keeps the Moon from flying off into space. If you pick up an object then let go of it, it falls down because of gravity.

What You'll Need:

• ball of crumpled aluminum foil What to Do:

1. Hold the book in one hand and the rubber ball in the other hand.

2. Put your arms straight out in front of you. Make sure the book and the ball are the same distance from the floor.

3. Let go of the book and the ball at exactly the same time. Watch them drop. Do they hit the floor at the same time?

4. Repeat the experiment several times. Use a different pair of objects each time: a ball and a spoon, a pencil and a marble, a book and a ball of crumbled aluminum foil, and so on. Do the objects always hit the floor at the same time?

What Happened:

The objects you dropped—the book, ball, spoon, pencil, marble, and ball of crumpled aluminum foil—were pulled down by gravity. The force of gravity on all these objects is equal, no matter how big or heavy they are. Therefore, all the objects fall at the same speed. In each part of this experiment, the pair of items you dropped fell at the same speed and hit the floor together.

One Step Further:

Try the experiment with a pencil and a flat piece of paper. Now crumble up the paper and try it again. Do the two objects hit the floor at the same time in both cases? Why or why not?

Questions:

I. Why do objects fall down instead of up?

2. If you wanted to travel to Mars, how would you overcome Earth's gravity?

3. Gravity is stronger on bigger planets. Pluto is the smallest planet in our solar system. Can you name a planet that has stronger gravity than Pluto?

4. Earth is larger than the Moon. Could you jump higher on the Moon or on Earth? Explain your answer.

5. The gravity of a black hole is so strong that nothing can escape it. not even light. What do you think happens to things that are pulled into a black hole?

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