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 applied to the chain (as shown in figure) in the duration from `x = 0 to x = L`. For chain to move with constant speed

Options

A. The magnitude of P should increases with time
B. The magnitude of P should decreases with time
C. The magnitude of P should increases first and then decrease with time
D. The magnitude of P should decrease first and then increases with time

Answer

A

Explanation

For chain to move with constant speed P need to be equal to friction force on the chain As the length of chain on the rough surface increase Hence the friction force `f_(1) = mu_(s) N` increase