question_answer

A boy projects a stone vertically perpendicular to the trolley car with a speed \[v\]. If the trolley car moves with \[u\]constant velocity m, the time of flight of the stone is:

A) \[\frac{u+v}{g}\]         

B) \[\frac{2v}{g}\]

C) \[\frac{2u}{g}\]            

D) none of these

Correct Answer: B

Solution :

[b] \[{{v}_{0}}\sin \theta =v\] \[{{v}_{0}}\cos \theta =u\] Time of flight depends on vertical component of velocity. \[T=\frac{2{{v}_{0}}\sin \theta }{g}=\frac{2v}{g}\]