Question

How does the trajectory of a ball change when it ciollides with anither ball

Answer 1

Answer:

When the two balls have exactly the same mass and experience a perfectly elastic collision where one ball was initially at rest, the final trajectory of the other ball is perpendicular to the line AB (in the figure). This is because as A strikes B, all of the momentum/velocity of it along line AB is transferred to B, which means the only velocity that can remain in A must be perpendicular to AB, which is tangent to the point of contact and couldn't cause any collision.