Q.
Two forces, each equal to $F$, act as shown in figure. Their resultant is
A) $\frac{F}{2}$
B) $F$
C) $\sqrt{3}\ F$
D) $\sqrt{5\ }F$
Explanation
(b) Note that the angle between two forces is 120${^\circ}$ and not 60${^\circ}$.
$R^{2} = F^{2} + F^{2} + 2F^{2}cos120{^\circ}$
or $R^{2} = 2F^{2} + 2F^{2}\left( - \frac{1}{2} \right) = F^{2}$
or $R = F$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.