Question

A chair is resting on the floor of room. when will the force of friction acts between them? where does the force act?Is the magnitude of the force constant?
Answer me first... urgent..

Answer 1

The force of friction will act on the chair when the chair will be pushed forward. The force act on the chair. The magnitude of force will different because it is pushed foward.

Answer 2

force of friction works when there is tendency of relative motion between two surfaces.
when we will apply force to chair in any direction except vertical(downward or upward),force of friction will act .
developed friction may be static(if there is doesn't slide over floor). or it may be kinetic(when there is relative motion between chair and floor).