Discussion Forum

A wheel of radius R and mass M is placed at the bottom of a fixed step of height R as shown in the figure. A constant force is continuously applied on the surface of the wheel so that it just climbs the step without slipping. Consider the torque  $\tau$ about an axis normal to the plane of the paper passing through the point Q. Which of the following options is/are correct ?

Answer:

Explanation:

(a) If force is applied normal to surface at  P, then the line of action of force will pass from  Q and thus $\tau$ =0

(b) wheel can climb

(c) $\tau=F(2R\cos\theta)-mgR\cos\theta$

             $\tau\propto\cos\theta$

Hence, as θ increases, $\tau$ decreases so it correct

(d)

$\tau =Fr_{\perp}-mg\cos\theta:\tau$ increases with θ