Question

A body throws balls vertically upwards. He throws one, while the previous one is at its highest point. Maximum height reached by a ball if he throws one ball each per second at uniform speed is

• A. $19.6m$
• B. $9.8m$
• C. $4.9m$
• D. $2.45m$

Answer 1

Answer: (C)

$4.9m$

Since, he throws one ball each per second, so time taken by ball to reach the maximum height $=1sec$
$\Rightarrow h=\frac{u^2}{2g}$

$\Rightarrow h=ut-\frac{1}{2}g{t}^2$

At, $t=1sec$
$v=u-gt=u-\frac{g}{2}=9-\frac{g}{2}$
$t=1sec\Rightarrow u=g-\left(1\right)=\frac{g}{2}=4.9m$