A proton of mass m is moving with initial speed v0 directly toward the center of a nucleus of mass 31m, which is initially at rest. Because both carry positive electrical charge, they repel each other. Find the speed v' of the nucleus for the following conditions:
a) the distance between the two is at it's smallest value.
b) the distance between the two is very large.
The Attempt at a Solution
At first I guessed 0 for both, just because.
So, since it's an elastic collision, the p and the KE remain the same before and after the collision.
divide both sides by m
multiply by 2/m
checking this, this is the case during (b) but not during (a)
I feel like I've missed something, probably not considering the fact that the two are pushing against each other at close distances but I'm not 100% sure how to account for that.