Question

A lift in which a man is standing, is moving upwards with a speed of $10m/s$. The man drops a coin from a height of $4.9m$ and if $g=9.8m/s^2$, then the coin reaches the floor of the lift after a time

• A. $\sqrt{2}$ $s$
• B. $1$ $s$
• C. $\frac{1}{2}s$
• D. $\frac{1}{\sqrt{2}}s$

Answer 1

The correct option is B $1$ $s$

Using relative terms
$u_{rel}=0m/s$
$a=9.8m/s^2,S=4.9m,t=?$

$4.9=0\times t+\frac{1}{2}\times 9.8\times t^2$
$\Rightarrow 4.9t^2=4.9$
$\Rightarrow t=1s$