Question

If the block is pulled by a force F which is always tangential to the surface then, the work done by this force between A and B is

• A. $F\pi R$
• B. $\sqrt{2}FR$
• C. $\frac{\pi }{2}FR$
• D. FR

Answer 1

The correct option is C $\frac{\pi }{2}FR$

The work done will be W = Force$\times$Displacement

Here the displacement will be the radius R

as the force is tangential always to the surface thus the angle subtended will be $\frac{\pi }{2}$

Thus dW= force$\times$ds, where ds = ( R$\times$$\pi$/2)

W = $\frac{\pi }{2}$ FR