Question

Determine the point of application of net force, when forces of 20 N & 30 N are acting on the rod as shown in figure.

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

Answer 1

The correct option is A

70 cm from point $A$

Net force acting on the rod $F_{net}$ = 10N

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 be at a distance $x$ from point $C$

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

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