Question

If a number of forces act on a body and the body is in static or dynamic equilibrium, then:

• A. work done by any individual force must be zero
• B. net work done by all the forces is +ve
• C. net work done by all the forces is -ve
• D. net work done by all the forces is zero

Answer 1

Answer: (D)

When a number of forces act on a body and the body is in static or dynamic equilibrium (It means $F_{\text{net}}=0$), then individual force may do the work, but net work done by all the forces will be zero.

[Note: In such a situation, work done by some forces is positive while by others is equally negative, so that net work becomes zero.]