Question

When a body slides against a rough horizontal surface, the work done by friction is ___________

(a) Positive

(b) Zero

(c) Negative

(d) Constant

The question was asked in unit test.

Enquiry is from Work, Energy and Power topic in section Nature of Physical World of Engineering Physics I

Answer 1

The correct answer is (c) Negative

For explanation I would say: If a force acting on a body has a component in the opposite direction of displacement, the work done is negative, when a body slides against a rough horizontal surface, its displacement is opposite to that of the force of friction. He works done by the friction is negative.