Question

An object is thrown between two tall buildings $180\text{m}$ from each other. The object is thrown horizontally from a window $55\text{m}$ above ground from one building to a window $10.9\text{m}$ above ground in the other building. Find out the speed of projection in $\text{m/s}$. (Use $g=9.8{\text{m/s}}^2$)

Answer 1

Height through which the object falls $=(55-10.9)\text{m}=44.1\text{m}$
Time taken for a body projected horizontally to fall through height $h$,
$t=\sqrt{\frac{2h}{g}}=\sqrt{\frac{2\times 44.1}{9.8}}$
$\Rightarrow t=3\text{sec}$
Horizontal range $R=ut$
i.e $180=u\times 3$ where $u$ is the speed of projection.
$\Rightarrow u=60\text{m/s}$