Question

In each of the following, a force (see figure) F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.

• A. In case of figure (a) $W=0$ because the force acts in the perpendicular direction of displacement.
• B. In case of figure (b) W is positive, because the force acts in the direction of displacement.
• C. In case of figure (c) W is negative, because the force acts in the direction opposite to the displacement.
• D. Data insufficent

Answer 1

Answer: (A), (B), (C)

The correct options are
A In case of figure (a) $W=0$ because the force acts in the perpendicular direction of displacement.
B In case of figure (c) W is negative, because the force acts in the direction opposite to the displacement.
C In case of figure (b) W is positive, because the force acts in the direction of displacement.

Work done can be positive,negative or zero.

Work done is positive when applied force and displacement is in same direction.Hence figure (b) shows positive work done.

Work done is negative when applied force and displacement is in opposite direction.Hence figure (c) shows negative work done.

Work done is zero when applied force and displacement is perpendicular.Hence figure (a) shows positive work done.