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A ball moving with a velocity v hits a m...

A ball moving with a velocity `v` hits a massive wall moving towards the ball with a velocity a. An elastic impact lasts for time `/_\t`

A

The average elastic force acting on the ball is `[m(u+v)]///_\t`

B

The average elastic force acting on the ball is `[2m(u+v)\]///_\t`

C

The kinetic energy of the ball increases by `2"mu" (u + v)`.

D

The kinetic energy of the ball remains the same after the collision.

Text Solution

Verified by Experts

The correct Answer is:
B, C
In an elstic collision `v_(sep)=v_(app)`
or `v'-u=v+u` or `v'=v+2u`

change in momentum of ball is
`|p_f-p_i|=|m(-v')-mv|=m(v'+v)=2mu(u+v)`
Average force is `(/_\P)/(/_\t)=(2m(u+v))/(/_\t)`
change in `KE`, `K_(f)-K_(i)=1/2mv^('2)=2mu(u+v)`
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Knowledge Check

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    C
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    D
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