Question

A ball is thrown vertically downwards with speed $30\text{m/s}$ from the top of the tower of height $80\text{m}$. The speed of the ball with which it hits the grounds is $(g=10{\text{m/s}}^2)$

• A. $40\text{m/s}$
• B. $60\text{m/s}$
• C. $50\text{m/s}$
• D. $30\text{m/s}$

Answer 1

The correct option is C $50\text{m/s}$

By equation of uniformly accelerated motion
$v^2=u^2+2aS$
$v=\sqrt{v_0^2+2gh}$
$\Rightarrow v=\sqrt{(30{)}^2+2\times 10\times 80}$
$\Rightarrow v=50\text{m/s}$