Kinematics Question 517
Question: Two balls A and B are thrown with speeds $ u $ and u/2, respectively. Both the balls cover the same horizontal distance before returning to the plane of projection. If the angle of projection of ball b is $ 15{}^\circ $ with the horizontal, then the angle of projection of a is
Options:
A) $ {{\sin }^{-1}}( \frac{1}{8} ) $
B) $ \frac{1}{2}{{\sin }^{-1}}( \frac{1}{8} ) $
C) $ \frac{1}{3}{{\sin }^{-1}}( \frac{1}{8} ) $
D) $ \frac{1}{4}{{\sin }^{-1}}( \frac{1}{8} ) $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] $ \frac{u^{2}\sin 2\theta }{g}=\frac{{{(u/2)}^{2}}\sin 30{}^\circ }{g}=\frac{u^{2}}{8g} $
$ \therefore \sin 2\theta =\frac{1}{2} $ or $ \theta =\frac{1}{2}{{\sin }^{-1}}( \frac{1}{8} ) $
