Question

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 τ about an axis normal to the plane of the paper passing through the point Q. Which of the following options is/are correct?

(A) If the force is applied at point P tangentially then decreases continuously as the wheel climbs
(B) If the force is applied normal to the circumference at point X then τ is constant
(C) If the force is applied normal to the circumference at point P then τ is zero
(D) If the force is applied tangentially at point then τ* ≠ 0 but the wheel never climbs the step

Answer 1

(C) If the force is applied at P tangential than the I *** constant and is equal to F × 2R where F is the applied force.
If force is applied normal to X, then as the wheels climbs, then the perpendicular distance of force from Q will go on changing initially the perpendicular is QM, later it becomes QM'.

If the force is applied normal to the circumference at point P then I is zero. So (C) is correct. If the force is applied tangentially at point * then