Question

From a lift moving upward with uniform acceleration $a$, a man throws a ball vertically upwards with an velocity $V$ relative to the lift. The time after which it comes back to the man is (in seconds)

• A. $\frac{2V}{g+a}$
• B. $\frac{2V}{g-a}$
• C. $\frac{V}{g+a}$
• D. $\frac{V}{g-a}$

Answer 1

The correct option is A $\frac{2V}{g+a}$

acceleration of the lift is given $a$.

taking every thing with respect to lift.

speed of the ball relative to lift is $=V$, similarly acceleration of the ball with respect to lift is $-g+-a=-(g+a)$(acceleration of lift) [taking upwards direction as positive].

so time of flight of body moving vertical is given by $\frac{2V}{g+a}$.

so best possible answer is option A.