Question

In order that the water shall never rise more than 100 cm above the crest for a discharge of 5 cubic meters per second, the length of the wire will be:

• A. 1 meter
• B. 2.5 meters
• C. 2.49 meters
• D. 2.51 meters

Hint:

Remember to use appropriate coefficients and units when solving weir discharge problems.

Answer 1

The Correct Option is C

The length of a rectangular weir is determined using its discharge formula:

\( Q = L \cdot H^{1.5} \cdot C_d \)

In this formula, \( Q \) represents discharge, \( L \) is the weir's length, \( H \) is the head, and \( C_d \) is the coefficient of discharge. By substituting \( Q = 5 \, \text{m}^3/\text{s} \), \( H = 1 \, \text{m} \), and an assumed standard \( C_d = 1.84 \), the calculated weir length is approximately \( 2.49 \, \text{meters} \).