Two smooth balls `A` and `B`, each of mass `m` and radius `R`, have their centres as shown in fig. Ball `A`, moving along positive x-axis, collides with ball `B`. Just before the collision, speed of ball `'A'` is `4m//s` and ball `'B'` is stantionary. The collision

Coefficient of restitution during the collision is changed to `(1)/(2)`, keeping all other parameters unchanged. What is the velocity of the ball `'B'` after the collision.

Explanation

By Newton's experimental law
`(1)/(2)=(v_(2)-v_(1))/((4cos30^(@)))`
`v_(2)-v_(1)=sqrt3` ......(i)
By conservation of momentum along line of collision
`m(4sqrt3)/(2)=mv_(1)+mv_(2)`
`v_(1)+v_(2)=2sqrt3` .....(ii)
From equation(i) & (ii),
`v_(1)=(sqrt3)/(2)m//s," "v_(2)=(3sqrt3)/(2)m//s`
`vecv_(1)=(3sqrt3)/(2)[cos30^(@)hati+sin30^(@)(-hatj)]m//s`
`=((9)/(4)hati-(3sqrt3)/(4)hatj)`