Q. The resultant of two forces, one double the other in magnitude, is perpendicular to the smaller of the two forces. The angle between the two forces is
A) $60{^\circ}$
B) $120{^\circ}$
C) $150{^\circ}$
D) $90{^\circ}$
Explanation
(b) $\tan\alpha = \frac{2F\sin\theta}{F + 2F\cos\theta} = \infty$ (as $\alpha = 90{^\circ})$
$\Rightarrow F + 2F\cos\theta = 0$
$\Rightarrow \cos\theta = - \frac{1}{2}$
$\theta = 120{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.