Elastic Collisions Video Lessons

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Problem: Two billiard balls with the same mass m move in the direction of one another. Ball one travels in the positive x-direction with a speed of V1i, and ball two travels in the negative x-direction with a speed of V2i. The two balls collide elastically, and both balls change direction after collision. If the initial speeds of the balls were v1i=2.0m/s and v2i =1.0m/s, what would be the final speed and direction of ball two, v2f, in m/s?

FREE Expert Solution

Conservation of momentum:

Pi=Pf

Therefore:

mv1i-mv2i=-mv1f+mv2fv1i-v2i=-v1f+v2f-v1f+v2f=v1i-v2i-v1f+v2f=2.0-1.0v1f=v2f-1

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Problem Details

Two billiard balls with the same mass m move in the direction of one another. Ball one travels in the positive x-direction with a speed of V1i, and ball two travels in the negative x-direction with a speed of V2i. The two balls collide elastically, and both balls change direction after collision. If the initial speeds of the balls were v1i=2.0m/s and v2i =1.0m/s, what would be the final speed and direction of ball two, v2f, in m/s?

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