Gravitational Forces!

1. Sep 30, 2009

ahealy88

(a) Calculate the magnitude of the gravitational force exerted on a 787-kg satellite that is a distance of two earth radii from the center of the earth= 8.48*10^-14

(b) What is the magnitude of the gravitational force exerted on the earth by the satellite? (In Newtons)

(c) Determine the magnitude of the satellite's acceleration. (m/s^2)

(d) What is the magnitude of the earth's acceleration (m/s^2)

2. Sep 30, 2009

tiny-tim

Welcome to PF!

Hi ahealy88! Welcome to PF!

Show us what you've tried, and where you're stuck, and then we'll know how to help!

3. Sep 30, 2009

ahealy88

Thank you! :)
I've tried the F=G(m1m2/r^2) and F=ma and I'm not getting anywhere.

4. Sep 30, 2009

tiny-tim

(try using the X2 and X2 tags just above the Reply box )

Well, have you done a) then?

If not, show us your calculations, so that we can see what's going wrong.

5. Sep 30, 2009

ahealy88

The answer to A was given to me, its 8.48*10-14

6. Sep 30, 2009

ahealy88

I don't know how to get A; I'm completely lost in this problem.

7. Sep 30, 2009

tiny-tim

You know g, the gravitational acceleration at one Earth radius …

so what is the gravitational acceleration at two Earth radii?

(and then use F = ma)

8. Sep 30, 2009

ahealy88

that did not help.

what i have is the mass of earth=5.9742*10^24
G= 6.674*10^11

my equation did not add up= 6.674*10^11(5.9742*10^24 * 787 / 12756.2^2)

9. Sep 30, 2009

ahealy88

and i have no idea how to figure out b,c, & d

10. Sep 30, 2009

ahealy88

Help!

11. Oct 1, 2009

tiny-tim

You don't need the mass of the Earth!

You know g, the gravitational acceleration at one Earth radius …

so what is the gravitational acceleration at two Earth radii?