Question

A body is projected horizontally from the top of a tower with $30m{s}^{-1}$. If $g=10m{s}^{-2}$, the velocity of that body after $4$ seconds is

• A. $40m{s}^{-1}$
• B. $30m{s}^{-1}$
• C. $50m{s}^{-1}$
• D. $20m{s}^{-1}$

Answer 1

The correct option is C $50m{s}^{-1}$

At $‘A^{\prime }$ there is no vertical conponent

At $‘B^{\prime }$ after $4$ seconds.

$V_1=0+gt=10\times 4=40$ m/s

The resultant velocity $V$,

$\begin{array}{c}V=\sqrt{{40}^2+{30}^2}\\ =\sqrt{1600+900}\\ =\sqrt{2500}\\ =50m/s\end{array}$

Hence, Option $C$ is correct.