Two solid balls A and B having masses 200 g and 400 grespectively are moving in opposite direction with velocity of A equal to 0.3 m//s. After the collision the two balls come to rest. The velocity of B before collision is :

Options

A. `- 0.15 m//s`
B. `1.5 m//s`
C. `0.1 m//s`
D. zero

Answer

a

Explanation

Hence (b) is the right choice. 107. Initial momentum = Final momentum
`m_(1)u_(1)+m_(2)u_(2)=(m_(1)+m_(2))0`
`u_(2)=(-200xx0.3)/(400)=-0.15m//s`
Hence correct choice is (a).