A straight 100 m long raw water gravity main is to carry water from an intake structure to the jack well of a water treatment plant. The required flow through this water main is 0.21 m /s. Allowable velocity through the main is 0.75 m/s. Assume f = 0.01, g = 9.81 m/s . The minimum gradient (in cm/100 m length) to be given to this gravity main so that the required amount of water flows without any difficulty is __________.

A straight 100 m long raw water gravity main is to carry water from an

1.	A straight 100 m long raw water gravity main is to carry water from an intake structure to the jack well of a water treatment plant. The required flow through this water main is 0.21 m /s. Allowable velocity through the main is 0.75 m/s. Assume f = 0.01, g = 9.81 m/s . The minimum gradient (in cm/100 m length) to be given to this gravity main so that the required amount of water flows without any difficulty is __________.
A.	4.8 cm
B.	4.01 cm
C.	5.8 cm
D.	3.025 cm
Answer» B. 4.01 cm

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