# Ball Hitting Stationary Blocks

1. Jun 14, 2015

### rockerdude1210

1. The problem statement, all variables and given/known data

Objects A and C are made of different materials, with different “springiness,” but they have the same mass and are initially at rest. When ball B collides with object A, the ball ends up at rest. When ball B is thrown with the same speed and collides with object C, the ball rebounds to the left. Compare the velocities of A and C after the collisions. Is vA greater than, equal to, or less than vC?

1. vA > vC

2. vA = vC

3. vA < vC

2. Relevant equations

P=mv

3. The attempt at a solution

I thought that since the ball stopped in the case of A, all of the energy would be transferred to A and that it would have the higher final velocity. However, the correct answer was tha vC was greater than vA and I wasn't sure why

2. Jun 14, 2015

### ehild

The energy need not conserve during a collision, but the momentum conserves. Which of A and C get greater momentum during the collision?

3. Jun 17, 2015

Ah I get it,

Thanks!