Question

A stone is dropped from a cliff. Find its speed after the stone has fallen from 100 m. Acceleration due to gravity$g=9.8\frac{m}{s^2}$

• A. 9.8 m/s
• B. 19.6 m/s
• C. 44.2 m/s
• D. 24 m/s

Answer 1

The correct option is C

44.2 m/s

It is a case of free fall under the gravity of the Earth. So the body would accelerate with 'g'.

The initial velocity $u=0$

distance travelled $s=100m$
Therefore, $v^2$​ = $u^2$​ + 2as (a = g)
$v^2$​​ =​ 0 + 2 $\times$ 9.8 $\times$ 100
$v^2=1960$
$v=\sqrt{1960}=44.2\frac{m}{s}$