Question

A stone projected vertically upwards reaches to the level of window $10m$ from the ground. Find the magnitude of the velocity of the stone at the time of its projection.

• A. ${7ms}^{-1}$
• B. ${36ms}^{-1}$
• C. ${28ms}^{-1}$
• D. ${14ms}^{-1}$

Answer 1

The correct option is D ${14ms}^{-1}$

Height attained by the stone thrown vertically upwards

$h=10m$

Velocity of projection

$u=\sqrt{2gh}$

$u$: Initial velocity

$g$: Acceleration due to gravity

$h$: Height attained by the object

$\Rightarrow u=\sqrt{2\times 10\times 9.8}$

$\Rightarrow u=14m/s$