Two blocks of masses `5 kg` and `2 kg` are placed on a frictionless surface and connected by a spring. An external kick gives a velocity of `14 m//s` to the heavier block in the direction of lighter one. The magnitudes of velocities of two blocks in the centre of mass frame after the kick are, respectively,

Options

A. `4m//s,4m//s`
B. `10m//s,4m//s`
C. `4m//s,10m//s`
D. `10m//s,10m//s`

Answer

C

Explanation

`v_(CM)=(5xx14)/(5+2)=10m//s`
velocity of the `5kg` block w.r.t `CM=14-10=4m//s`
Velocity of the `2kg` block w.r.t `CM =0-10=-10m//s`