Question

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

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

Answer 1

Answer: (B)

up the incline while ascending as well as descending

Answer 2

mg $\sin heta$ component is always down the plane whether it is rolling up or rolling down.Therefore, for no slipping, sense of angular acceleration should also be same in both the cases.
Therefore, force of friction f always act upwards.