A body of mass `m_(1) ` moving with uniform velocity of 40 m/s collides with another mass `m_(2)` at rest and then the two together begin to moe wit h uniform velocity of 30 m/s. the ratio of their masses `(m_(1))/(m_(2))` is

Options

A. `1:3`
B. `3:1`
C. `1:1.33`
D. `1:0.75`

Answer

B

Explanation

(b) Initial momentum of the system
`m_(1)xx40+m_(2)xx0=40m_(1)`
Final momentum of the system=`(m_(1)+m_(2))xx30)`
By the law of consevation of momentum,
Initial momentum= Final momentum
`40m_(1)=(m_(1)+m_(2))30 `
`40 m_(1)-30m_(1)=30m_(2)`
`10m_(1)=30m_(2)`
`(m_(1))/(m_(2))=3/1`