A moon (3.312*10^15 kg) is orbited by a satellite at 15km. What is the gravitational acceleration that the moon exerts on the satellite as it's in orbit? Also, what force does the moon exert on the satellite (1500 kg) while in orbit?

Question

anonymous · Answer

Let's start with Newton's second law: $$F=ma$$ The force in this case is: $$\frac{Gm _{1}m _{2}}{r ^{2}}$$ So using Newton's second law (and the fact that gravitational acceleration = g = a) $$g=\frac{Gm _{satellite}}{r ^{2}}$$ where$$G=6.67*10^{-11}N \frac{m ^{2}}{kg ^{2}}$$

anonymous · Answer

I made a mistake above, you should use $$m _{moon}$$ instead of the mass of the satellite above.
 
As for the second part of the question, use the mass of the satellite in the 3rd equation above. You can see that g will be much smaller!

anonymous · Answer

Okay, I think I understand. Thanks for your help!