A block of mass `12 kg` moving on a rough horizontal surface having `(mu_(k) = 0.5, mu_(s) = 0.6)` with a speed `2 m//s` at any instant and a 12 N force is acting opposite to its motion as shown in figure. Friction force acting on the block is

Options

A. `72 hat(i) N`
B. `-72 hat(i) N`
C. `60 hat(i) N`
D. `-60 hat(i) N`

Answer

C

Explanation

`f_("max") = mu_(k) N`
`= mu_(k) xx 12g`
`= 0.5 xx 120`
`60 N`
since block is in motion kinetic friction acts on it.