Question

A bob of mass m is pulled along a circular arc by means of a constant horizontal force P as shown. Work done by the force P while lifting the bob from A to B is:

• A. mgl
• B. $\frac{Pl}{2}$
• C. Pl
• D. $\sqrt{\frac{3}{2}PL}$

Answer 1

The correct option is B $\frac{Pl}{2}$

Given,

Horizontal displacement, $s=l\sin {30}^o=\frac{l}{2}$

Work done, $W=Force\times displacement=P.s=P.\frac{l}{2}$

Hence, work done by force $P$ is $\frac{pl}{2}$