Question

Two ball `A` and `B` having masses 1kg and 2kg, moving with speeds `21m//s` amd `4m//s` repectively in opposite direction, collide head on. After collision `A` moves with a speed of `1m//s` in the same direction, then correct statements is:
A. The velocity of `B` after collision is `6m//s` opposite to its direction of motion before collision.
B. The coefficient of restitution is `0.2`.
C. The loss of kinetic energy due to collision in 200J.
D. The impulse of the force between the two balls is `40Ns`.

Answer 1

Correct Answer - A::B::C
Multi correct
(A)
Using conservation of linear momentum
`1xx1+2xxv=1xx21-2xx4" "rArrv=+6m//s`
(B) `e=(6-1)/(21+4)=0.2`
(C) Loss in `K.E.=(1)/(2)(m_(1)m_(2))/(m_(1)+m_(2))(u_(1)-u_(2))^(2)(l-e^(2))`
`=(1)/(2)((2)/(3))(25)^(2)(1-0.04)=200J`
(D)`I=p_(f)-p_(i)=2(+6)-2(-4)=20Ns`