Question:
How many litres of water flows out of a pipe having an area of cross section of 5 cm2 in 1 minute, if the speed of water in the pipe is 30 cm/sec?
Solution:
Speed of the water = 30 cm/s
Area of the cross section = 5 cm2
Volume of the water flowing out of the pipe in one second = Area of the cross section × 30 cm = 5 × 30 = 150 cm3
Now, 1 minute = 60 seconds
∴ Volume of the water flowing out of the pipe in 60 seconds
= Volume of the water flowing out of the pipe in one second × 60
= 150 × 60
= 9000 cm3
$=\frac{9000}{1000} \quad\left(1 \mathrm{~L}=1000 \mathrm{~cm}^{3}\right)$
= 9 L
Thus, 9 L of water flows out of the given pipe in 1 minute.