Two planets of mass 3 x 1025kg are release from rest 1.5 x 1012 m apart. What is the speed of the planets when they are half this distance apart?

Help! I've been stuck on this for a good bit! I cant seem to find a formula that can help me solve this! I can find the force but i don't know what to do with it!

1 answer

I think this will help:

https://www.physicsforums.com/threads/two-bodies-attracting-via-gravitation.413391/