Problem 1.31

# Problem 1.31 - Problem 1.31[Difficulty 3 Given Information...

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Problem 1.31 [Difficulty: 3] Given: Information on canal geometry. Find: Flow speed using the Manning equation, correctly and incorrectly! Solution: Use Table G.2 and other sources (e.g., Google) as needed. The Manning equation is V R h 2 3 S 0 1 2 n = which assumes R h in meters and V in m/s. The given data is R h 7.5 m = S 0 1 10 = n 0.014 = Hence V 7.5 2 3 1 10 1 2 0.014 = V 86.5 m s = (Note that we don't cancel units; we just write m/s next to the answer! Note also this is a very high speed due to the extreme slope S 0 .) Using the equation incorrectly: R h 7.5 m 1in 0.0254 m × 1f t 12 in × = R h 24.6 ft = Hence V 24.6 2 3 1 10 1 2 0.014 = V 191 ft s = (Note that we again don't cancel units; we just write ft/s next to the answer!) This incorrect use does not provide the correct answer V 191 ft s 12 in 1f t × 0.0254 m 1in × = V 58.2 m s =

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## This note was uploaded on 10/19/2011 for the course EGN 3353C taught by Professor Lear during the Fall '07 term at University of Florida.

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Problem 1.31 - Problem 1.31[Difficulty 3 Given Information...

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