Which of the following statements is `//`are true.

Options

A. work done by kinetic friction on an object may be positive.
B. A rigid body rolls up an inclined plane without sliding. The friction force on it will be up the incline. (only contact force and gravitational force is acting)
C. A rigid body rolls down an inclined plane without sliding. The friction force on it will be up the incline. (only contact force and gravitational force is acting)
D. A rigid body is left from rest and having no angular velocity from the top of a rough inclined plane. It moves down the plane with slipping. The friction force on it will be up the incline.

Answer

A, B, C, D

Explanation

Which of ………..
Work done by kinetic friction may be positive when it acts aiong motion of the body. Friction on rigid body rolling on inclined plane is along upward because tendency of slipping is downwards.