A cylinder rolls up an inclined plane, reaches some height, and then rolls down (without slipping throughout these motions). The directions of the frictional force acting on the cylinder are :

Options

A. up the incline while ascending and down the incline while descending
B. up the incline while ascending and up the incline while descending
C. down the incline while ascending and upt the incline whole descending
D. down the incline while ascending as well as descending

Answer

B

Explanation

As `mg sin theta` component always acts down the plane whether the cylinder moves up or down, the angular acceleration will remain the same in both cases (in the absence of any slipping). Therefore, force of friction always acts up the plane.