# Question #56ea6

##### 1 Answer

The acceleration at a distance of

#### Explanation:

The question in your photo is asking about gravity a short distance above the surface of the earth. 60 miles sounds like a lot, but the earth has a radius of 4000 miles.

The gravitational force is calculated using this equation:

Where

Comparing

In the Mars example we must change R to twice the value of R. So we are comparing these two equations:

A little algebra turns that second equation into:

Or, writing that a little more clearly:

And it should be clear that the gravitational force at this distance is one quarter what it is at the surface.

To be completely clear, this

So the acceleration will be:

But it should be easy to show that this is in the same proportions at the differences in F.