Question

A ball is projected from ground with a velocity $v$ at an angle $\theta$ to the vertical. On its path, it makes an elastic collision with a vertical wall and returns to 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 won’t be any change in the time period of flight as in an elastic collision the ball will bounce with same angle as angle of incidence and with same velocity as incident velocity. So, the trajectory after collision will be just like mirror image of original trajectory about the wall.
Therefore, the time of flight will remain unchanged.
$\frac{2v\cos \theta }{g}$