A body of mass 40kg resting on a rough horizontal surface is subjected to a force `P` which is just enough to start the motion of the body. If `mu_(s)=0.5mu_(k)=0.4 , g=10ms^(-2)` an dthe force `P` is continuously applied on the body, then the accceleration of the body is.

Options

A. zero
B. `1m//s^(2)`
C. `2m//s^(2)`
D. `2.4m//s^(2)`

Answer

b

Explanation

When body is just to start moving then force
`F =mu_(s) mg`
When body starts moving with acceleration a then
`F - F_(k) = ma`, where `F_(k) = mu_(k) mg`
or `mu_(s) mg-mu_(k) mg = ma`
or `a= (mu_(s) -mu_(k)) g = (0.5 -0.4) xx 10 = 1ms^(2)` .