# B How do you know the size/maximum area of a gravity field

1. Mar 20, 2017

### Steven Hansel

The title said it, how do you know the size or maximum area of a planet's gravity field can cover. The reason i asked this question because from the gravity equation the r is the radius from Mplanet and Mobject. So, that doesn't explain how big is the gravity field. Is it when the gravity force become 0?

2. Mar 20, 2017

### FactChecker

There is no maximum. The gravitational effects go forever. They may become negligible, since it decreases proportional to 1/r2, but it never completely disappears. As object A gets farther from one other object B and closer to a third object, C, the gravitational effect of C may become greater than that of B, but the effect of B is still there.

3. Mar 20, 2017

### Steven Hansel

Thanks for the answer, i still have one more question that i forgot to ask, why does gravitational force weakens as it get farther from a planet. I'm really confused. I also don't understand why when you get near fire it's hot and when you get away from it, you don't get any heat. thanks for answering!

4. Mar 20, 2017

### FactChecker

For heat from a fire, the energy of a source gets spread out, so less of it hits another object of a fixed size as it gets farther away.
For gravity, the true answer is beyond my expertise on the subject. A mass distorts space-time in a certain way that is the subject of General Relativity.

5. Mar 20, 2017

### Steven Hansel

Okay, that really helped me to where i should find my answer, thanks for answering :)

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted