A block of mass `m` is pushed up against a spring, compressing it a distance `x`, and the block is then released. The spring projects the block along a frictionaless horizontal surface, grving the block a speed `v`. The same spring projects a second block of mass `4m`, giving it a speed `3v`. What distance was the spring compressed in the second case ?

Options

A. `6x`
B. `x//6`
C. `36x`
D. `12x`

Answer

A

Explanation

`1/2 mv^2 = 1/2 kx^2 " "…..(i) " " 1/2 (4m) (3v^2) = 1/2 k(x)^(2) " "….(ii)`.