An object rolls down a rough incline without slipping
PHYSICS · Single correct · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
An object rolls down a rough incline without slipping. Which statement best explains why its mechanical energy is conserved even though friction is present?
(a) Because the component of gravity parallel to the surface exactly balances the static friction force, no work is done by friction.
(b) Because the object rolls without slipping, there is actually no friction acting on it, so mechanical energy is conserved.
(c) The static friction force does no work because the point of contact is instantaneously at rest relative to the surface.
(d) The negative work done by static friction is exactly offset by an equal increase in rotational kinetic energy, so total mechanical energy remains constant.