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Gravity: Top 10 Questions

September 2010

Thanks to Alex Miller, Brian Pierre, Jake Forsberg, and Pamela Ward; Microgravity Project Team Members, Boise State University for the answers.

1: What causes gravity?

Gravity is caused by the mass of objects. The larger the mass, the more gravity it has. That's why the moon has less gravity than the Earth does. Its mass is less. (From Cole in Mrs. Peterson's class at Owyhee Elementary School in Boise)

2: Why isn't there gravity in space?

There is gravity in space. There's gravity everywhere. When you see astronauts in space, it looks like they are floating. However, gravity is affecting them just like it's affecting us on Earth. (From Quinn in Mrs. Peterson's class at Owyhee Elementary School in Boise)

3: How fast do you have to go to escape the atmosphere?

You can escape the atmosphere at any speed you want, but for us on Earth, there is a term called "escape velocity." This is the speed you would have to go to never come back to Earth. It's about seven miles a second, which is very, very fast. (From Kaleb in Mrs. Peterson's class at Owyhee Elementary School in Boise)

4: Will Saturn smash you like a pancake because it has so much gravity?

The mass of Saturn is much greater than the mass of Earth. So, if we were to stand on Saturn, we would feel much more forced toward its surface. Depending on the exact mass of Saturn, it is possible that it could smash us. (From Kyle in Mrs. Stoddard's class at Owyhee Elementary School in Boise)

5: Does the sun keep Pluto in orbit?

The sun is so huge and has such strong gravitational pull that it is able to keep all of the planets in orbit, including Pluto, which is really far away. (From Reagan in Mrs. Hunt's class at Cynthia Mann Elementary School in Boise)

6: Does the moon have gravity?

Everything that has mass has gravitational force associated with it. Therefore, the moon does have gravity. If you were there, you would feel the gravitational force. The Earth has so much more mass than the moon that its gravitational force keeps us on its surface. When we see astronauts on the moon, they bounce around (or can jump higher than we can on Earth) because gravity there is less strong. (From Victor in Mrs. Hunt's class at Cynthia Mann Elementary School in Boise)

7: Why do feathers float?

Feathers float because of air resistance. A feather has a lot of surface area. As a feather falls downward, air pushes up on it. The air is able to push on it enough that it essentially cancels out gravity. Therefore it falls more slowly to the ground. (From Lauren in Mrs. Schweitzer's class at Riverside Elementary School in Boise)

8: Why do we need gravity?

Gravity is very important to us. The solar system would not even exist without gravity. Planets were made from gas that condensed due to gravitational force over a long period of time. We have gravity to thank for everything. If there were no gravity, we wouldn't be here. (From Isabel in Mrs. Schweitzer's class at Riverside Elementary School in Boise)

9: How can you make zero gravity on an airplane?

When an airplane's flight pattern is a parabola (up and down, up and down), it creates a feeling of weightlessness right at the top as it's changing from going up to going down. It's not really zero gravity. It's that you are falling at the same rate as gravity, so you don't feel the effects of gravity on you. (From Sarah in Eagle)

10: What causes black holes?

Black holes are suspected to be very, very massive objects that collapse in on themselves because of their own gravity to a point where they are very, very tiny. They have so much gravity that nothing can escape them. This includes light, which is why we call them black holes. (From Adam who is home schooled)


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