Question

Is it possible that a body to be in accelerated motion under a force acting on the body, yet no work is being done by the force? Explain your answer giving a suitable example.

Answer 1

yes , it is possible.

as you know, workdone is the dot product of force applied on body and displacement of body.

e.g., $W=\vec{F}.\vec{S}$

or, $W=FScos\theta$

where, $\theta$ is angle between force and displacement.

in this equation, it is clear that workdone will be zero when

1. F = 0, S = 0

2. F = 0 , S ≠ 0

3. F ≠ 0, S = 0

4. F ≠ 0, S ≠ 0 but $\theta=90^{\circ}$

hence, there are two possible conditions 3. F ≠ 0 , S = 0 and 4.F ≠ 0, S ≠ 0 but $\theta=90^{\circ}$ where a body to be in accelerated motion under a force acting on body , yet no work is being done by the force.