A block of mass m is on an inclined plane of angle `theta`. The coefficient of friction between the block and the plane is `mu` and `tanthetagtmu`. The block is held stationary by applying a force P parallel to the plane. The direction of force pointing up the plane is taken to be positive. As P is varied from `P_1=mg(sintheta-mucostheta)` to `P_2=mg(sintheta+mucostheta)`, the frictional force f versus P graph will look like

Options

A.
B.
C.
D.

Answer

a

Explanation

Initially the frictionl force (which is limiting force of friction) is upwards and is maximum When force applied `(P)` is increased the body starts moving The dynamic frictional force decreases and its direction is reversed Thus graph (a) is correct .