A body of mass `m_(1)` moving with a velocity `3 m//s` collides with another body at rest of `m_(2)` . After collision the velocities of the two bodies are `2 m//s` and `5 m//s` , respectively , along the direction of motion of `m_(1)`. The ratio `m_(1)//m_(2)` is

Options

A. `5/12`
B. 5
C. `1/5`
D. `12/5`

Answer

D

Explanation

`v_(2)^(') = ((m_(2)-m_(1))/(m_(2)+m_(1))v_(2) + (2m_(1))/(m_(1)+m_(2))v_(1)`
`v_(1) = 0`
`therefore` `v_(2)/v_(2)^') = (m_(2)+m_(1)/(m_(2)-m_(1)) = (m+2m)/(m-2m) = -3`
`therefore` `K_(2)/K_(2)^(') = (v_(2)/v_(2)^('))^(2) = 9`