Question

A ball is projected from ground with a velocity $v$ at an angle $\theta$ on the vertical. On its path it makes an elastic collision with a vertical wall and returns to the ground. The total time of flight of the ball is :

• A. $\frac{2v\sin \theta }{g}$
• B. $\frac{2v\cos \theta }{g}$
• C. $\frac{v\sin 2\theta }{g}$
• D. $\frac{v\cos \theta }{g}$

Answer 1

The correct option is B $\frac{2v\cos \theta }{g}$

Even after the collision there will be no change in the time period of flight as in an elastic collision the ball will bounce with same angle as angle of incident and with same velocity as incident velocity so the trajectory will be just like mirror image of original trajectory about the wall.
so time of flight will remain unchanged i.e.,$\frac{2v\cos \theta }{g}$