A block of metal weighing 2kg is resting on a frictionless plane. It is struck by a jet releasing water at a rate of `1kg s^(-1)` and at a speed of `5ms^(_1)`. The initial acceleration of the block is

Options

A. `2.5m//s^(2)`
B. `5m//s^(2)`
C. `10m//s^(2)`
D. `20m//s^(2)`

Answer

A

Explanation

The water jet striking the block at the rate of `1kg//s` at a speed of `5m//s` will exert a force on the block
`F=v(dm)/(dt)=5xx1=5N` .
Under the action of this force of `5N` , the block of mass `2kg` will move with an acceleration given by
`a=(F)/(m)=(5)/(2)=2.5m//s^(2)` .