# Fluid Mechanics Questions and Answers – Characteristics of Surface Profiles

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Characteristics of Surface Profiles”.

1. A surface profile is a measure of _______
a) Temperature changes
b) Pressure changes
c) Flow changes
d) Volumetric changes

Explanation: Surface profile is a measure of flow changes that are developed in the fluid body. It is developed longitudinally. Thus, the reason for the surface profile is due to flow changes in the system.

2. The surface profile is classified into normal depth and critical depth.
a) True
b) False

Explanation: Surface profile is a measure of flow changes that are developed in the fluid body. It is developed longitudinally. It is divided into normal depth and critical depth. Thus, the answer is true.

3. What is the condition for a normal depth?
a) Water depth remains a constant
b) Temperature of fluid remains a constant
c) Pressure of fluid remains a constant

Explanation: 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.

4. 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

Explanation: 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.

5. When the depth is normal, which parameter is zero?
a) Pressure
b) Temperature
c) Volume
d) Acceleration

Explanation: 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. During a normal formation of a normal depth, there is no acceleration of flow.

6. Which among the following is the Manning’s equation?
a) Q = A/v
b) Q = vA
c) Q = v+A
d) Q = v-A

Explanation: Manning’s equation is one of the most commonly used equations governing the open channel glow. It is an alternative to the Chezy’s equation. It is an empirical equation that applies to uniform flow in open channels.

7. Manning’s equation is not used to calculate_________
a) Normal depth
b) Roughness
c) Critical depth

Explanation: Manning’s equation is an empirical equation that applies to uniform flow in open channels. Manning’s equation is used to calculate normal depth, roughness, wetted area and the hydraulic radius.

8. When the energy is at minimum for flow discharge, it is called _________
a) Normal depth
b) Roughness
c) Critical depth

Explanation: Critical depth is defined as the depth at which the energy is at minimum for flow discharge. The flow of profile is classified into three zones for a better understanding. Thus, The correct answer is Critical depth.

9. Normal depth occurs only for a uniform and steady flow.
a) True
b) False

Explanation: Normal depth occurs only for a uniform and steady flow. 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.

10. Subcritical depth occurs when_________
a) Actual water depth > Critical depth
b) Actual water depth < Critical depth
c) Actual water depth = Critical depth
d) They are independent

Explanation: Subcritical depth occurs when actual water depth is greater than the critical depth. It is dominated by gravitational forces and behaves in a slow and stable way.

11. During a subcritical flow, what is value of Froude’s number?
a) Zero
b) Greater than one
c) Less than one
d) Not defined

Explanation: Subcritical depth occurs when actual water depth is greater than the critical depth. It is dominated by gravitational forces and behaves in a slow and stable way. The Froude’s number is less than one during a subcritical flow.

12. Supercritical depth occurs when_________
a) Inertial forces behave as unstable flow
b) Roughness is high
c) Critical depth increases

Explanation: Supercritical depth occurs when the inertial forces behaves as a rapid and an unstable flow. Supercritical flow transition to subcritical flow takes place through a hydraulic jump due to high energy loss.

13. During a supercritical flow, what is value of Froude’s number?
a) Zero
b) Greater than one
c) Less than one
d) Not defined

Explanation: Supercritical depth occurs when the inertial forces behaves as a rapid and an unstable flow. Supercritical flow transition to subcritical flow takes place through a hydraulic jump due to high energy loss. It has a Froude number greater than one.

14. During a critical flow, what is value of Froude’s number
a) Zero
b) Greater than one
c) Less than one
d) Equal to one

Explanation: Critical flow is a flow in which the control flow possesses the minimum possible energy for a particular flow rate. Critical flow has a Froude’s number equal to one.

Sanfoundry Global Education & Learning Series – Fluid Mechanics.

To practice all areas of Fluid Mechanics, here is complete set of 1000+ Multiple Choice Questions and Answers. 