Rich example

Problem

A particle of mass $\quantity{10}{kg}$ starts at rest on a rough inclined plane. A force of magnitude $\quantity{P}{N}$ is applied to the particle and acts up the slope, parallel to the plane.

When $P = 20$ the particle is on the point of sliding down the plane.

When $P = 40$ the particle is on the point of sliding up the plane.

Describe how the particle moves and calculate the frictional force when the force applied is:

• $P = 25$
• $P = 30$
• $P = 50$

What would a graph of the frictional force against $P$ look like?