Question

The head of water over a rectangular weir is 38 cm. The length of the crest of the weir end contraction suppressed is 1.3 m. Find the discharge using the Francis formula.

(a) 0.56 m^3/s

(b) 0.75 m^3/s

(c) 0.85 m^3/s

(d) 0.69 m^3/s

The question was posed to me by my school principal while I was bunking the class.

Question is from Time Required to Empty a Reservoir with  Weirs or Notches topic in chapter Orifices, Mouthpieces, Notches and Weirs of Fluid Mechanics

Answer 1

Correct answer is (a) 0.56 m^3/s

For explanation I would say: Q = 1.84*L*H^1.5 = 0.56 m^3/s.