Question

A wheel of diameter $2m$ is shown with the axle at 'O'. A force $F=2N$ is applied at B in the direction as shown in the figure.

Calculate the moment of force about

(i) centre 'O', and

(ii) point A

• A. (i) $2Nm$
  (ii) $4Nm$
• B. (i) $2Nm$
  (ii) $2Nm$
• C. (i) $4Nm$
  (ii) $4Nm$
• D. (i) $4Nm$
  (ii) $2Nm$

Answer 1

The correct option is A (i) $2Nm$

(ii) $4Nm$

Force $F=2N$

(1) :

Perpendicular distance between point O and B, $r=\frac{diameter}{2}=\frac{2}{2}=1m$

Moment of force about centre O, ${\tau }_O=rF=1\times 2=2Nm$

(2) :

Perpendicular distance between point A and B, $r=diameter=2m$

Moment of force about centre A, ${\tau }_A=rF=2\times 2=4Nm$