Is vA Greater Than, Equal to, or Less Than vC After the Collisions?

[rockerdude1210]

Homework Statement

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

Homework Equations

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P=mv

The Attempt at a Solution

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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

 

[ehild]

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

 

[rockerdude1210]

Ah I get it,

Thanks!