A farmer connect a pipe of internal diameter 20 cm from a canal into a cylindrical tank which is 10 m diameter and 2 m deep. If the water flows through the pipe at the of 4 km/hr, in how much time will the tank be filled completely?


Given: diameter of pipe = 20 cm


radius of pipe = rp = 20/2 = 10 cm = 0.1 m


Diameter of tank = 10 m


radius of cylindrical tank = rc = 10/2 = 5 m


Depth of cylindrical tank = height of cylindrical tank = h = 2 m


Rate of flow of water through pipe = 4 km/hr


1 km = 1000 m


4 km/hr = 4000 m/hr


Volume of water required to completely fill the tank is equal to the volume of cylinder


Time require to fill the tank = volume of cylindrical tank/volume of water flown through pipe per hr


volume of cylindrical tank = π × rc2 × h


= 3.14 × 25 × 2


= 157 m3


volume of water flown through pipe per hr = π × rp2 × 4000


= 3.14 × 0.12 × 4000


= 3.14 × 40


= 125.6 m3/hr


Time require to fill the tank = 157/125.6


= 1.25 hrs


Therefore, it will take 1.25 hours to fill the tank completely.


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