Question

A Cipolletti weir has the crest length of 1.2 m and a crest water level of 0.5 m. The average
approach velocity of water in m s-1 on the crest is
(A) 0.49 (B) 1.18 (C) 1.19 (D) 1.32

Answer 1

Newton's second law of motionpertains to the behavior of objects for which all existing forces are not balanced. The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.

Answer 2

The correct answer is option (C) 1.19.

The equation involved in solving this question is

Q = 0.018 L.√(H)³

where

Q = discharge rate

L = weir length in cm

H = head length in cm

L = 1.2 m = 120 cm

H = 0.5 m = 50 cm

Now, √(H³) =√ (50³) = 353.5

On putting values,

Q = 0.018 * 120 * 353.5

Q = 763.67 liter/sec

or, Q = 0.76 m³/sec

So, the nearest value is 1.19 m/sec

On putting values, you obtain the correct answer as 1.1987 ~ 1.19 m³/sec.