Question

A lift is moving up with acceleration a. A person inside the lift throws the ball upwards with a velocity u relative to hand. What is the time of flight of the ball?

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

Answer 1

Answer: (A)

$\frac{2u}{(g+a)}$

Acceleration of ball w.r.t lift $=a+g$

$\overline{s}=\overline{u}t+\frac{1}{2}{\overline{a}}_{BL}{t}^2$
$0=uT-\frac{1}{2}(g+a)T^2$
Therefore, the time of flight of the ball $T=\frac{2u}{(g+a)}$.