# Gravitational Force Problem?

## Homework Statement

The radius of the Earth is 6.86 e6 m and the mass of the earth is 5.98 e24kg. There is a satellite floating in space at a point where the earth's gravitational acceleration is 3.2 m/s^2.

How far above the earth's surface is the satellite?

Fg = Gmm/r^2

## The Attempt at a Solution

I know I need to find Fg - at least I think. But I dont know how to start...

## Answers and Replies

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rock.freak667
Homework Helper

Fg = Gmm/r^2

## The Attempt at a Solution

I know I need to find Fg - at least I think. But I dont know how to start...

The gravitational force of attraction provides the centripetal force. So you need to equate Fg and Fcentripetal (which you can just write as ma for this case).

The gravitational force of attraction provides the centripetal force. So you need to equate Fg and Fcentripetal (which you can just write as ma for this case).
ma - ok, I have the acceleration, but I get confused as to which "m" i am using. My problem is the intuition with formulas

Wow I reread the problem and I am extra confused. How do I figure out the mass of the shuttle?

rock.freak667
Homework Helper
Wow I reread the problem and I am extra confused. How do I figure out the mass of the shuttle?
You don't need it! if you have

ma= GMm/r2

an 'm' (the mass of the shuttle) cancels out

Ahhh so 3.2 = G(5.98e24)/R^2. Then solve for R?

rock.freak667
Homework Helper
Ahhh so 3.2 = G(5.98e24)/R^2. Then solve for R?
Yes, but be aware of what that R is.