Problem based on Rotational Motion #2

Question

One fourth length of a Uniform Rod of mass $m$ and length $x$ is placed on rough horizontal surface and it is held stationary by means of a light thread as shown in the figure. The thread is brunt and the rod starts rotating about the edge, the co-efficient of friction of the surface is $μ$. Determine the angle between the rod and the horizontal surface at which the rod is about to slip on the edge.

I am confused on 'How the friction force would act?'or basically the FBD (Free Body Diagram).

Answer 1

To a good approximation the frictional force, i.e. the force you need to make the rod slide, is equal to $\mu$ times the normal force between the rod and the table. You just have to work out when the component of the gravitational force directed along the rod exceeds the frictional force.

Answer 2

The friction force acts along the rod, from the edge of the table to the top end of the rod.