Question

Calculate the total torque acting on the body shown in figure about the point $O$.

• A. 0.54 N - m
• B. 0.45 N - m
• C. 54 N - m
• D. 45 N - m

Answer 1

The correct option is A

0.54 N - m

Torque about a point = Total force $\times$ perpendicular distance from the point to that force.

Let anticlockwise torque = + ve

And clockwise acting torque = - ve

Force acting at the point B is 15 N

Therefore torque about O due to this force

= $15\times 6\times {10}^{-2}\times sin{37}^{\circ }$

= $15\times 6\times {10}^{-2}\times \frac{3}{5}$ = 0.54 N-m (anticlock wise)

Force acting at the point C is 10 N

Therefore, torque about O due to this force

= $10\times 4\times {10}^{-2}$ = 0.4 N-m (clockwise)

Force acting at the point A is 20 N

Therefore, Torque about O due to this force = $20\times 4\times {10}^{-2}\times sin{30}^{\circ }$

= $20\times 4\times {10}^{-2}\times \frac{1}{2}$ = 0.4 N-m (anticlockwise)

Therefore resultant torque acting about 'O' = 0.54 - 0.4 + 0.4 = 0.54 N-m.