Conservation of Mass in Fluid Mechanics: Interactive Learning Quizzes

Question 1

In a steady, incompressible fluid flow system, which of the following statements about mass flow rate is true?

Accepted Answer

Mass flow rate remains constant at all sections of a pipe with a constant cross-sectional area.

Answer

Mass flow rate is always negative if the flow is reversed.

Answer

Mass flow rate is directly proportional to the temperature of the fluid.

Answer

Mass flow rate is independent of the density of the fluid.

Question 2

Which of the following correctly defines the principle of mass conservation in fluid mechanics?

Accepted Answer

Total mass in a fluid flow system remains constant over time.

Answer

Mass can be created or destroyed in a fluid flow system.

Answer

Mass can be transferred between different parts of a system, but the total mass outside the system may change.

Answer

Mass is conserved only in steady-state flow conditions.

Question 3

For fluid flowing through a pipe with varying cross-sectional area, which of the following relationships must hold true to satisfy mass conservation?

Accepted Answer

Mass flow rate is constant throughout the pipe.

Answer

Velocity is constant throughout the pipe.

Answer

Density is constant throughout the pipe.

Answer

Pressure is constant throughout the pipe.

Question 4

In a steady, incompressible flow in a closed loop, which of the following must remain constant?

Accepted Answer

Mass flow rate

Answer

Velocity

Answer

Pressure

Answer

Temperature

Question 5

Which statement does not describe a consequence of mass conservation in fluid mechanics?

Accepted Answer

Fluid density can vary with temperature and pressure.

Answer

Total mass of a closed system remains constant.

Answer

Fluid velocity can vary along a streamline.

Answer

Mass flow rate through any cross-section of a pipe remains constant

Question 6

Which of the following is a direct consequence of the mass conservation principle in fluid flow systems?

Accepted Answer

The mass flow rate into a system must equal the mass flow rate out of the system.

Answer

Mass can be created or destroyed within the system.

Answer

The velocity of the fluid must be constant throughout the system.

Answer

The density of the fluid must be constant throughout the system.

Question 7

Which of the following flow measurement devices is based on the principle of mass conservation?

Accepted Answer

Venturimeter

Answer

Hot-wire anemometer

Answer

Laser Doppler velocimeter

Answer

Ultrasonic flowmeter

Question 8

A control volume in fluid mechanics is defined as:

Accepted Answer

A fixed region of space through which fluid flows.

Answer

A moving boundary that encloses a fluid.

Answer

A surface that separates two different fluids.

Answer

A point through which fluid passes.

Question 9

The differential form of the mass conservation equation is:

Accepted Answer

ρ(∂u/∂x + ∂v/∂y + ∂w/∂z) = 0

Answer

ρ(∂u/∂t + ∂v/∂y + ∂w/∂z) = 0

Answer

ρ(∂u/∂x + ∂v/∂t + ∂w/∂z) = 0

Answer

ρ(∂u/∂t + ∂v/∂t + ∂w/∂t) = 0

Question 10

Which of the following is a key assumption of the mass conservation principle?

Accepted Answer

The fluid is continuous.

Answer

The fluid is incompressible.

Answer

The fluid is inviscid.

Answer

The fluid is irrotational.

Question 11

In engineering and industry, what are the key applications of the mass conservation principle?

Accepted Answer

Designing pipelines and selecting pumps

Accepted Answer

Analyzing combustion systems

Accepted Answer

Optimizing energy efficiency

Answer

It is not used in engineering or industry

Question 12

**Statement of Conservation of Mass Principle**

Which statement accurately describes the conservation of mass principle in fluid mechanics?

Accepted Answer

Mass entering a system minus mass leaving the system equals the rate of mass accumulation within the system

Answer

Mass entering a system is always greater than mass leaving the system

Answer

Mass entering a system minus mass leaving the system must be zero

Question 13

**Application of Conservation of Mass in Fluid Flow**

A pipe carrying water has a diameter of 5 cm at section A and 10 cm at section B. The velocity of water at section A is 2 m/s. What is the velocity at section B?

Accepted Answer

0.5 m/s

Answer

2 m/s

Answer

4 m/s

Answer

1 m/s

Question 14

**Key Assumption for Conservation of Mass**

Which is a key assumption for applying the conservation of mass principle to a fluid flow system?

Accepted Answer

The fluid is incompressible

Answer

The fluid is inviscid

Answer

The flow is turbulent

Question 15

**Limitation of Conservation of Mass Principle**

Which is a limitation of the conservation of mass principle?

Accepted Answer

It does not account for chemical reactions or phase changes

Answer

It requires the fluid to be incompressible

Answer

It is only applicable to steady flow systems

Question 16

**Conservation of Mass in Systems with Multiple Inlets and Outlets**

In a fluid flow system with multiple inlets and outlets, which of the following is true?

Accepted Answer

The sum of the mass flow rates entering the system must equal the sum of the mass flow rates leaving the system

Answer

The mass flow rate at any inlet must be equal to the mass flow rate at any outlet

Question 17

The principle that states that the mass flow rate entering a steady-state control volume must equal the mass flow rate leaving it is known as:

Accepted Answer

Conservation of Mass

Answer

Conservation of Energy

Answer

Bernoulli's Equation

Answer

Conservation of Momentum

Question 18

Which of the following is a direct consequence of the conservation of mass in fluid flow systems?

Accepted Answer

The total mass of fluid within a closed system remains constant.

Answer

The density of the fluid remains constant throughout the system.

Answer

The pressure of the fluid increases as the velocity decreases.

Question 19

In a compressible fluid flow, where density changes with pressure and temperature:

Accepted Answer

The mass flow rate is not constant and varies with the density changes.

Answer

The mass flow rate remains constant despite density changes.

Answer

The conservation of mass principle is not applicable.

Question 20

Which of the following is a fundamental assumption when applying the conservation of mass principle to fluid flow systems?

Accepted Answer

The fluid can be treated as a continuum.

Answer

The fluid is incompressible.

Answer

The flow is turbulent.

Question 21

In a converging nozzle, where the velocity of a fluid increases as it passes through:

Accepted Answer

The density of the fluid decreases.

Answer

The density of the fluid becomes zero.

Answer

The density of the fluid remains constant.

Answer

The density of the fluid increases.

Question 22

In a closed-loop fluid flow system, the mass flow rate at any given point is:

Accepted Answer

Equal to the mass flow rate at any other point in the system.

Answer

Dependent on the velocity of the fluid at that point.

Answer

Proportional to the pressure at that point.