. A chain of length L is placed on a horizontal surface as shown in figure
At any instant x is the length of chain on rough surface and the remaining portion lies on smooth surface. Initially x = 0. A horizontal force P is implied to the chain (as shown in figure ). in the duration x changes from x = 0 to x = L, for chain to move with constant speed.
A. the magnitude of P should increase with time
B. the magnitude of P should decrease with time
C. the magnitude of P should increase first and then decrease with time
D. the magnitude of P should decrease first and then increase with time