Question

Forces of 20 N & 30 N are acting on the rod as shown in the figure. Where should an external force of 10 N be applied so that the body is in equilibrium?

• A. 70 cm from point
• B. 30 cm from
• C. 40 cm from
• D. 60 cm from

Answer 1

The correct option is A

70 cm from point

External force acting on the rod $F_{ext}$ = 10 N

Net torque acting on the rod about point $C$

${\tau }_C$ = (20 $\times$ 0) + (30 $\times$ 20) = 600 N-cm clockwise

Let the point of application of external force be at a distance $x$ from point $C$

$600=10x\Rightarrow x=60cm$

$\therefore$ 70 cm upwards from A is the point of Application of the net force.