Question

State the condition when the work done by a force is (a) positive, (b) negative. Explain with the help of examples.

Answer 1

(a) When the displacement of the body is along the direction of the force applied, work done is positive.
E.g. Gravitational force does positive work on a body falling from some height.

(b) When the displacement of the body is opposite to the direction of the force, work done is negative.
E.g. work done by friction on a sliding body is negative.