Question

In the figure above, Calculate the torque about the pendulum suspension point produced by the weight of the bob, given that the mass is 40 cm below the suspension point, measured vertically, and m = 0.50 kg.

• A. $0.49N\times m$
• B. $0.98N\times m$
• C. $1.7N\times m$
• D. $2.0N\times m$
• E. $3.4N\times m$

Answer 1

The correct option is B $0.98N\times m$

Given : $m=0.5kg$ $L=40cm=0.4m$

Torque about suspension point $\tau =LF$ $sin\theta$ where $\theta$ is the angle between $\overrightarrow{L}$ and $\overrightarrow{F}$

From figure, $\theta ={30}^o$

$⟹$ $\tau =L\left(mg\right)sin{30}^o=0.4\times (0.5\times 9.8)\times 0.5=0.98$ Nm