Question

Two Juptier sized planets are released from rest 1.0 x 10^11 m apart. What are their speeds as they crash into each?

Answer 1

The mechanical energy is conserved.
1/2 mv^2+Gm/r=constant
From here we can find v and x as well.

Answer 2

I mean r :)

Answer 3

So m doesn't matter in this problem, right?

Answer 4

Since it's equal, it cancels each other.

Answer 5

ok, cool

Answer 6

Good luck :)

Answer 7

wouldn't vf =0?

Answer 8

What does vf stands for? final velocity?

Answer 9

yea

Answer 10

Lol, you're quite right. But the problem ask for v just the moment before collision. It isn't 0.

Answer 11

oh, gotcha