Question

Water is being pumped out through a circular pipe whose internal diameter $7cm$. If the flow of water is $72cm$ per second, how many liters of water are being pumped out in one hour?

Answer 1

we have,
Radius of the circular pipe $\frac{7}{2}cm$

Clearly, water column forms a cylinder of radius $\frac{7}{2}cm$

It is given that the water flows out at the rate of $72cm/sec$

Length of the water column flowing out in one second$=72cm$

Volume of the cylinder of radius $\frac{7}{2}cm$ and length $72cm$

$\Rightarrow$ $\pi {\left(\frac{7}{2}\right)}^2\times 72{cm}^3=\frac{22}{7}\times \frac{7}{2}\times \frac{7}{2}{cm}^3=2772{cm}^3$

Volume of water flowing out in one hour

$\Rightarrow$ $(2772\times 3600){cm}^3=9979200{cm}^3=\frac{9979200}{1000}litres=9979.2litres$