# Rubber ball colliding with steel ball of equal mass

1. The problem statement, all variables and given/known data
Suppose a rubber ball collides head-on with a steel ball of equal mass traveling in the opposite direction with equal speed. Which ball, if either, receives the larger impulse? Explain.

2. Relevant equations
p = m*v
impulse force = change in p

3. The attempt at a solution

(1) At first I intuitively thought that since the rubber ball is more "bouncy" than the steel ball, it’ll likely bounce off after the collision and travel in the opposite direction at a greater speed than the steel ball will. So I thought that the rubber ball will have larger change in momentum, and thus will exert more impulse, meaning the steel ball will receive the larger impulse.

(2) But then, I began thinking that my intuition may not be correct. The momentum change must be the same for both balls regardless of whether they’re steel or rubber, meaning the impulse force must be equal….also, impulse is nothing more than the integral of the force exerted during some time interval. The balls collide for the exact same time interval, and the force exerted by the balls on each other is also the same.

Is answer (2) correct? If so, would the answer remain the same if the question were changed to the following: "Suppose a rubber ball collides head-on with a steel ball of equal mass traveling in the opposite direction with **DIFFERENT** speeds."

Thanks a lot.

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