Question

define coefficient of limiting friction. on what factors does it depend? what is its unit? what happens to it, when the weight of the body is doubled?

Answer 1

Coefficient of limiting friction is the coefficient of friction for the two body just before it starts moving. This can be find out for the maximum static friction divided by its normal force.

It depends on the type of the surface.

This is an unit less and dimension less quantity as it is the ratio of two forces.

The coefficient of friction will not change as it depends of surface not weight but the frictional force will be doubled.