Episode 2: Gravity For Breakfast

gregwebb44Space Train

Doug and the Cadets take their first trip to outer space and learn about gravity. (Duration: 19:34) Get access to all of the Purple Rocket Podcast episodes for free by downloading the RadioPublic app HERE. Theme music by Kevin Macleod – Incompetech.com. Want to listen offline? Click the download icon on the player above to download this episode to your device.

 

Discussion

Have a conversation with your child about gravity.

Definition: The force that attracts a body toward the center of the earth, or toward any other physical body having mass.

Demonstrate the effects of gravity by having your child jump up and down or throw a ball up in the air and catch it. Explain that gravity is what’s pulling them (or the ball) back down to the ground. If there wasn’t any gravity, when they jumped they would float away.

Activity

Galileo’s Gravity Experiment: Gravity pulls everything down equally

Have your child find objects of different sizes around the house. Make sure they are droppable items. (example: balls, pencils, a book, stuffed animals, etc.)

Ask your child to take two of these objects and predict which one will hit the ground first if dropped at the same time. Your child will likely guess the heavier object. Then have them experiment, dropping two different items at the same time. If done correctly, they should both hit the ground at the same time. Explain that Gravity is what causes all objects to fall to the ground and that all objects fall at the same acceleration.

But, only one thing can change that, air resistance. It is the frictional force that air exerts on an object moving through it. For example, when you stick your hand out the window of a moving car, that force pushing your hand back is called air resistance. When you make your hand a fist, the force decreases.

Air resistance can work against gravity in decreasing the acceleration of a falling object.

Have your child take a sheet of paper and drop it at the same time as the other objects. They will find that the paper takes longer to reach the ground than the other items. Explain that this is because of the paper’s shape. Because it is wide and flat it has more surface for the air to push against, thus more air resistance.

Have them take two sheets of paper and crumple one of them into a ball and then drop both pieces of paper at the same time. The crumpled paper will now drop faster than the sheet because the shape has changed and it no longer has as much air resistance.

crumpled paper

But what would happen in the vacuum of space? Galileo, a famous astronomer from the 1500’s, predicted that all objects would fall at the same time in the absence of air.

Watch the video below to see if his prediction was right!