Fluid Mechanics Fundamentals for Civil and Mechanical Engineering
1. What is a fluid?
A) A substance that has a fixed shape
B) A substance that deforms continuously under an applied shear stress
C) A substance that cannot flow
D) A substance that is always a gas
Answer: B) A fluid is a substance that can flow and continuously deforms when subjected to a
shear stress.
2. Which of the following is NOT a fluid?
A) Water
B) Air
C) Steel
D) Oil
Answer: C) Steel is a solid and does not continuously deform under shear stress.
3. What is the primary difference between a liquid and a gas?
A) Liquids are compressible; gases are incompressible
B) Liquids have a definite volume; gases fill the entire volume of their container
C) Liquids flow; gases do not
D) There is no difference
Answer: B) Liquids have a definite volume, while gases expand to fill their container.
4. What is "density" (ρ) of a fluid?
A) Force per unit volume
B) Mass per unit volume
C) Weight per unit volume
D) Pressure per unit depth
Answer: B) Density is the mass of a fluid per unit volume (ρ = m/V).
5. What is "specific weight" (γ) of a fluid?
A) Mass per unit volume
B) Weight per unit volume
C) Force per unit area
D) Volume per unit mass
Answer: B) Specific weight is the weight of a fluid per unit volume (γ = ρg).
6. What is "specific gravity" (SG)?
A) The ratio of the density of a fluid to the density of water at a specified temperature
B) The density of a fluid in kg/m³
,C) The weight of a fluid per unit volume
D) The pressure of a fluid per unit depth
Answer: A) Specific gravity is a dimensionless number. Water at 4°C has an SG of 1.
7. What is the density of water at standard conditions?
A) 1000 kg/m³
B) 1.225 kg/m³
C) 9.81 kg/m³
D) 62.4 kg/m³
Answer: A) The density of water is approximately 1000 kg/m³ (or 1 g/cm³).
8. What is "viscosity" of a fluid?
A) A measure of a fluid's resistance to flow (internal friction)
B) A measure of a fluid's weight per unit volume
C) A measure of a fluid's compressibility
D) A measure of a fluid's surface tension
Answer: A) Viscosity is a measure of the fluid's resistance to shear stress.
9. What is the difference between "dynamic viscosity" (μ) and "kinematic viscosity" (ν)?
A) Dynamic viscosity depends on density; kinematic viscosity does not
B) Kinematic viscosity is dynamic viscosity divided by density (ν = μ/ρ)
C) There is no difference
D) Dynamic viscosity is used for gases; kinematic viscosity is used for liquids
Answer: B) Kinematic viscosity is the ratio of dynamic viscosity to density.
10. What is a "Newtonian fluid"?
A) A fluid where shear stress is proportional to the rate of strain (constant viscosity)
B) A fluid where shear stress is not proportional to the rate of strain
C) A fluid that is incompressible
D) A fluid that is compressible
Answer: A) In Newtonian fluids (e.g., water, air), viscosity is constant.
11. What is a "non-Newtonian fluid"?
A) A fluid with constant viscosity
B) A fluid where viscosity changes with the rate of strain (e.g., blood, ketchup, paint)
C) A fluid that is incompressible
D) A fluid that is a gas
Answer: B) Non-Newtonian fluids have variable viscosity.
12. What is "surface tension" in fluids?
A) The force per unit length acting at the surface of a liquid
, B) The force per unit area acting at the surface of a liquid
C) The pressure at the surface of a liquid
D) The density of a liquid at the surface
Answer: A) Surface tension is the property that allows insects to walk on water.
13. What is "capillary action"?
A) The rise or fall of a liquid in a narrow tube due to surface tension and adhesion
B) The flow of a liquid through a pipe
C) The evaporation of a liquid
D) The boiling of a liquid
Answer: A) Capillary action is important in soils and porous media.
14. What is "pressure" in a fluid?
A) Force per unit volume
B) Force per unit area
C) Mass per unit volume
D) Weight per unit volume
Answer: B) Pressure is defined as the normal force per unit area (P = F/A).
15. What is the SI unit of pressure?
A) Newton
B) Pascal
C) Joule
D) Watt
Answer: B) The Pascal (Pa) is the SI unit of pressure (1 Pa = 1 N/m²).
16. What is "atmospheric pressure" at sea level?
A) 101.3 kPa
B) 100 kPa
C) 1 MPa
D) 10 kPa
Answer: A) Standard atmospheric pressure is 101.3 kPa (or 1 atm).
17. What is "gauge pressure"?
A) The pressure relative to absolute zero
B) The pressure relative to atmospheric pressure
C) The absolute pressure
D) The pressure at the bottom of a container
Answer: B) Gauge pressure = Absolute pressure - Atmospheric pressure.
1. What is a fluid?
A) A substance that has a fixed shape
B) A substance that deforms continuously under an applied shear stress
C) A substance that cannot flow
D) A substance that is always a gas
Answer: B) A fluid is a substance that can flow and continuously deforms when subjected to a
shear stress.
2. Which of the following is NOT a fluid?
A) Water
B) Air
C) Steel
D) Oil
Answer: C) Steel is a solid and does not continuously deform under shear stress.
3. What is the primary difference between a liquid and a gas?
A) Liquids are compressible; gases are incompressible
B) Liquids have a definite volume; gases fill the entire volume of their container
C) Liquids flow; gases do not
D) There is no difference
Answer: B) Liquids have a definite volume, while gases expand to fill their container.
4. What is "density" (ρ) of a fluid?
A) Force per unit volume
B) Mass per unit volume
C) Weight per unit volume
D) Pressure per unit depth
Answer: B) Density is the mass of a fluid per unit volume (ρ = m/V).
5. What is "specific weight" (γ) of a fluid?
A) Mass per unit volume
B) Weight per unit volume
C) Force per unit area
D) Volume per unit mass
Answer: B) Specific weight is the weight of a fluid per unit volume (γ = ρg).
6. What is "specific gravity" (SG)?
A) The ratio of the density of a fluid to the density of water at a specified temperature
B) The density of a fluid in kg/m³
,C) The weight of a fluid per unit volume
D) The pressure of a fluid per unit depth
Answer: A) Specific gravity is a dimensionless number. Water at 4°C has an SG of 1.
7. What is the density of water at standard conditions?
A) 1000 kg/m³
B) 1.225 kg/m³
C) 9.81 kg/m³
D) 62.4 kg/m³
Answer: A) The density of water is approximately 1000 kg/m³ (or 1 g/cm³).
8. What is "viscosity" of a fluid?
A) A measure of a fluid's resistance to flow (internal friction)
B) A measure of a fluid's weight per unit volume
C) A measure of a fluid's compressibility
D) A measure of a fluid's surface tension
Answer: A) Viscosity is a measure of the fluid's resistance to shear stress.
9. What is the difference between "dynamic viscosity" (μ) and "kinematic viscosity" (ν)?
A) Dynamic viscosity depends on density; kinematic viscosity does not
B) Kinematic viscosity is dynamic viscosity divided by density (ν = μ/ρ)
C) There is no difference
D) Dynamic viscosity is used for gases; kinematic viscosity is used for liquids
Answer: B) Kinematic viscosity is the ratio of dynamic viscosity to density.
10. What is a "Newtonian fluid"?
A) A fluid where shear stress is proportional to the rate of strain (constant viscosity)
B) A fluid where shear stress is not proportional to the rate of strain
C) A fluid that is incompressible
D) A fluid that is compressible
Answer: A) In Newtonian fluids (e.g., water, air), viscosity is constant.
11. What is a "non-Newtonian fluid"?
A) A fluid with constant viscosity
B) A fluid where viscosity changes with the rate of strain (e.g., blood, ketchup, paint)
C) A fluid that is incompressible
D) A fluid that is a gas
Answer: B) Non-Newtonian fluids have variable viscosity.
12. What is "surface tension" in fluids?
A) The force per unit length acting at the surface of a liquid
, B) The force per unit area acting at the surface of a liquid
C) The pressure at the surface of a liquid
D) The density of a liquid at the surface
Answer: A) Surface tension is the property that allows insects to walk on water.
13. What is "capillary action"?
A) The rise or fall of a liquid in a narrow tube due to surface tension and adhesion
B) The flow of a liquid through a pipe
C) The evaporation of a liquid
D) The boiling of a liquid
Answer: A) Capillary action is important in soils and porous media.
14. What is "pressure" in a fluid?
A) Force per unit volume
B) Force per unit area
C) Mass per unit volume
D) Weight per unit volume
Answer: B) Pressure is defined as the normal force per unit area (P = F/A).
15. What is the SI unit of pressure?
A) Newton
B) Pascal
C) Joule
D) Watt
Answer: B) The Pascal (Pa) is the SI unit of pressure (1 Pa = 1 N/m²).
16. What is "atmospheric pressure" at sea level?
A) 101.3 kPa
B) 100 kPa
C) 1 MPa
D) 10 kPa
Answer: A) Standard atmospheric pressure is 101.3 kPa (or 1 atm).
17. What is "gauge pressure"?
A) The pressure relative to absolute zero
B) The pressure relative to atmospheric pressure
C) The absolute pressure
D) The pressure at the bottom of a container
Answer: B) Gauge pressure = Absolute pressure - Atmospheric pressure.
