Consider the rectangular weir described in Prob. 13.50. When the head is doubled, the discharge is 

(a) Doubled, 

(b) Less than doubled

(c) More than doubled.

Data from Prob. 13.50

A 3 m long rectangular weir is to be constructed in a 3 m wide rectangular channel, as shown (a). The maximum flow in the channel will be 4 m³/s. What should be the height P of the weir to yield a depth of water of 2 m in the channel upstream of the weir?