Say we have equal masses M1 and M2, traveling at equal but opposite velocities. Assume elastic collision. The forces are equal and they come to stop, then accelerate away from one another at same initial speeds.

But what if now we do same but one velocity is V, other is -2v. Is the force from above example the in this case? Wouldn't it have to be right, becuase the masses don't know how fast one is relative to the other, and the forces  have to be equal by N3l.  Just now they act longer, causing the change in momentum, such that the balls switch velocities compared to before the collision.


Just looking for clarification if I am thinking correctly of the forces during a collision.