A long long long time ago a scientist named Galileo declared that without air resistance any two objects would fall at the same rate. People laughed at Galileo for that, among other things. Anciently the Greek philosopher Aristotle had said heavier things fall faster than lighter things. It made sense and until Galileo no one thought any more about it.
Imagine a feather and a hammer. Which will hit the floor first? Imagine a piece of paper and a book. Which will hit the floor first? Easy. The hammer and the book will hit before the feather and the paper. True, true, they will indeed, unless you remove the air resistance.
On the moon, which has almost no air resistance, astronauts tried Galileo’s experiment. Here’s a video of what happened.
You can try your own experiment at home. Remember that paper and book? Get them out.
- Have one person hold the paper and one person hold the book. Drop them at the same time. Pay attention to what happens.
- Now place the paper on top of the book (make sure the book is at least as large as the paper). Now drop them both together. Observe what happened that time.
- Now answer the question why.
The paper doesn’t have less potential energy than the book, but it does have less mass, so the air affects the paper more. Remove the influence of the air and the paper falls at exactly the same rate as the book.
- Read more about Galileo. What other kooky things did he believe? And how did it get him into trouble?
- Have the kids write about where they would go if they could travel into space and what they would see and discover.
- Everything is impossible until it is proven to be true or until somebody does it. What impossible things have you dreamed about doing? Have a discussion about it with your kids.
- Enter NASA’s zero gravity experiment design contest.