Question

Water is supplied to a city population for general use (not for drinking) from a river through a cylindrical pipe. The radius of the cross-section of the pipe is $20cm$. The speed of water through the pipe os $18km$ per hour. Find the quantity of water in litres which is supplied to the city in two hours. (Take $\pi =3.14$ and $1m^3=1000$litres)

• A. $4521600$ litres
• B. $4528500$ litres
• C. $4571600$ litres
• D. $2221600$ litres

Answer 1

The correct option is A $4521600$ litres

Radius of pipe$=20cm$

Area of cross section of pipe $=\pi r^2=3.14\times 20\times 20=1256c{m}^2$

Speed of water through the pipe$=18km/hr$

Length of water flow in $2hr=2\times 18=36km=3600000cm$

Volume of water flow $=$ cross sectional area $\times$ length of water flow.

$=36000000\times 1256$

$=4521600000c{m}^3$

$=4521600000=\frac{4521600000}{1000}$ ..........$1000c{m}^3=1liter$
$=4521600liters$