Question

When gravitational force is equal to the friction drag, what type of depth is formed?

(a) Critical depth

(b) Normal depth

(c) Cylindrical depth

(d) Conical depth

The question was asked in an online quiz.

The above asked question is from Characteristics of Surface Profiles topic in chapter Non Uniform Flow in Channels of Fluid Mechanics

Answer 1

The correct choice is (b) Normal depth

To explain I would say: Normal depth is a depth of flow in the channel. It is created when the slope of the water surface and channel bottom is the same and the water depth remains the same throughout the entire flow. It is formed when gravitational force is equal to the friction drag.