Laws Of Motion Question 80
Question: 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 [KCET 2002]
Options:
A) $ {{60}^{\circ}} $
B) $ {{120}^{\circ}} $
C) $ {{150}^{\circ}} $
D) $ {{90}^{\circ}} $
Show Answer
Answer:
Correct Answer: B
Solution:
$ \tan \alpha =\frac{2F\sin \theta }{F+2F\cos \theta }=\infty $ (as$ \alpha =90{}^\circ $ ) therefore$ F+2F\cos \theta =0 $ therefore$ \cos \theta =-\frac{1}{2} $
$ \theta =120{}^\circ $
