Question

$ABC$ is an equilateral triangle with $O$ as its centre $\overset{ \rightarrow }{F}_{1},\overset{ \rightarrow }{F}_{2}$ and $\overset{ \rightarrow }{F}_{3}$ represent three forces acting along the sides $AB,BC$ and $AC$ respectively. If the total torque about $O$ is zero then the magnitude of $\overset{ \rightarrow }{F}_{3}$ is

• A. $\frac{F_{1} + F_{2}}{2}$
• B. $2\left( F_{1} + F_{2}\right)$
• C. $F_{1}+F_{2}$
• D. $F_{1}-F_{2}$

Answer 1

Answer: (C)

$\overset{ \rightarrow }{F}_{1}$ and $\overset{ \rightarrow }{F_{2}}$ produce torque in one sense while $\overset{ \rightarrow }{F_{3}}$ in another.