A slab of stone of mass S S\,S kg is positioned on a rough metal sheet inclined at an angle ϕ \phi\,ϕ to the horizontal. The stone is in limiting equilibrium, just about to slide down the sheet. The coefficient of friction between the stone and the sheet is 0.45.
Find the value of ϕ\phiϕ.
The stone slab is now projected down the sheet with speed 0.2 ms−1^{-1}−1. Describe the motion of the slab, giving a reason for your answer.