Question

check my understanding please.

Larry weighs 300 N at the surface of the earth. what is the weight of the earth in the gravitational field of Larry?
-would it still be 300 N

an astronaugt lands on a planet that has twice the mass as earth and twice the diameter. how does the astronaut weight differ from that on earth?
-his weight on earth would be less

if the moon pulls the earth as strongly as the earth pulls the moon, why doesnt the earth rotate around the moon, or why don't both rotate around a point midway between them?
-is it because they are in orbit and have a foce field

Answer 1

2) Isn't gravity force= GMm/d^2

3) Where is the center of mass for Earth/Moon. ISn't the center of mass what they both rotate around?