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 $



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