Eduprobe
Question:
A block of mass m is on an inclined plane of angle θ. The coefficient of friction between the block and the plane is μ and tan θ > μ. 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 P1 = mg(sin θ − μcos θ) to P2 = mg(sin θ + μcos θ), the frictional force f versus P graph will look like?
Solution:
As P is increased from mg(sin θ − μcos θ) to mg(sin θ + μcos θ) frictional force will change from mgcosθ ( upwards parallel to inclined plane) to 0 to mgcosθ (downwards parallel to inclined plane). Under the approximation of linear variation of P the correct option is A.