Water is flowing at the rate of 6 km/hr through a pipe of diameter 14 cm into a rectangular tank which is 60 m long and 22 m wide. Determine the time in which the level of water in the tank will rise by 7 cm.
Given,
Speed of the water flowing through the pipe, H = 6 km/hr
= 
cm/s
Diameter of the pipe = 14 cm
Radius (R) of pipe = 
= 7 cm
Length (l) of the rectangular tank = 60 m = 6000 cm,
Breadth (b) of the rectangular tank = 22 m = 2200 cm and
Height (h) or Rise in the level of water in the tank = 7 cm
Now,
Volume of the water in rectangular tank = l × b × h = 6000 x 2200 x 7 = 92400000cm3
Also,
Volume of the water flowing through the pipe in 1 s = πR2H
= 
cm3
So,
The time taken to rise the water = 
cm3
= 92400 x 
= 3600s = 1 hr
So,
In 1 hour time the level of water in the tank will rise by 7cm.