Question

In a rain-water harvesting system, the rain-water from a roof of 22 m x 20 m drains into a cylindrical tank having diameter of base 2 m and height 3.5 m. If the tank is full, find the rainfall in cm. Write your views on conservation.

Answer 1

Rectangular roof : $l=22m,b=20m$

Cylindrical tank : $r=1m,h=3.5m$

The volume of tank $=\pi r^{2}h$

$=\frac{22}{7}\times 1\times 1\times 3.5$

$=\frac{22}{7}\times \frac{35}{10}$

$=11m^3$

Area of roof $=l\times b=22\times 20=440m^2$

Rainfall $=\frac{\text{Volume of tank}}{\text{Area of roof}}$

$\therefore$ Rainfall $=\frac{11m^3}{440m^2}=0.025m$

$\therefore$ Rainfall is $2.5cm$