Question

A wheel of radius $R$ is free to rotate about its own axis. A tangential force $F$ is applied on the wheel along its rim. If $q$ is the angular displacement of wheel due to the force $F$, then work done by $F$ is:

• A. $RFq$
• B. $\frac{RF}{q}$
• C. $\frac{qF}{R}$
• D. $\frac{qR}{F}$

Answer 1

Answer: (A)

$RFq$

As F is applied at rim,

$\tau =F\times R$

$=FRsin\theta$
angular displacement $d\theta =q$
$\therefore workdone=\tau d\theta$ (standard formula of work and power)

$=FRq$