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31. Water is flowing at the rate of 2.52 km/h through a cylindrical pipe into a cylindricaltank, the radius of whose base is 40 cm. If the increase in the level of water in the tank,in half an hour is 3.15 m, find the internal diameter of the pipe. |
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Answer» Answer: INCREASE in the water level in half an hour = 3.15 m = 315 cm Radius of the water tank = 40 cm Volume of the water that FALLS in the tank in half an hour = πr²h = 22/7*40*40*315 = 1584000 cu cm Rate of the water FLOW = 2.52 km/hr Length of water column in half an hour = (2.52*30)/60 = 1.26 km = 126000 cm Let the internal diameter of the cylindrical pipe be d. Volume of water that FLOWS through the pipe in half an hour = π*(d/2)²*126000 As we KNOW that, Volume of the water that flows through pipe in half an hour = Volume of water that falls in the cylindrical tank in half an hour ⇒ 22/7*(d/2)²*126000 = 1584000 ⇒ 22/7*d²/4*126000 = 1584000 ⇒ d² = 16 ⇒ d = √16 ⇒ d = 4 So, the internal diameter of the pipe is 4 cm
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