# Fluid Mechanics Questions and Answers – Newton’s Second Law

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Newton’s Second Law”.

1. A point in a fluid flow where the flow has come to rest is called __________
a) Pressure point
b) Initial point
c) Flow point
d) Stagnation point

Explanation: Stagnation point is a point at which a flow field of the local velocity of a fluid is equal to zero. At this point, the fluid is brought to rest by the object. When the velocity is zero, the static pressure is maximum.

2. When a fluid is subjected to resistance, it undergoes a volumetric change due to __________
a) Strain
b) Cohesion
d) Compressibility

Explanation: Compressibility is defined as a measure of relative change in volume of a fluid. In fluid mechanics, it is also called as isothermal compressibility due to increase in pressure and temperature.

3. What does Kinematic Viscosity depend upon?
a) Density
b) Pressure
c) Fluid level
d) Fluid Flow

Explanation: Kinematic viscosity is a quantity that represents dynamic viscosity of a fluid per unit density. Density is a major factor that determines the kinematic viscosity. As the temperature increases, density decreases thereby causing changes in the density of the fluid.

4. What is the formula to find the kinematic viscosity of a fluid?
a) Dynamic Viscosity * Temperature
b) Dynamic Viscosity / Density
c) 1/ dynamic viscosity
d) Density / Dynamic Viscosity

Explanation: Density is a major factor that determines the kinematic viscosity. As the temperature increases, density decreases thereby causing changes in the density of the fluid. Thus, kinematic viscosity and density are inversely proportional.

5. A one dimensional flow is also called as __________
b) A flow which involves zero transverse component
c) Uniform Flow
d) Zig-Zag flow

Explanation: One dimensional flow is a flow in which variations of velocity and pressure occur along one space coordinate only. A good example of one dimensional flow is a flow through pipe. During a flow through a pipe, the functions of velocity and pressure occur along the length of the pipe.
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6. What is the resultant upward pressure of a fluid on an immersed body called?
a) Buoyancy
b) Metacentre
c) Upthrust
d) Reaction pressure

Explanation: Buoyancy has been explained by Archimedes Principle. The principle states that the force exerted is directly proportional to the pressure difference. This equivalent weight of the body immersed is equal to that of the fluid displaced.

7. If a mass of 1000kg of liquid occupies a volume of one cubic meter, then 1 represents which among the following?
a) Specific Density
b) Specific Weight
c) Specific Gravity
d) Specific Mass

Explanation: Specific Gravity is defined as the ratio of mass or density of a substance to that of the mass or density of a reference substance. But, provided that it has the same volume. It must also have a specified temperature and pressure.

8. At what temperature is the density of water the maximum?
a) 100oC
b) 0oC
c) 5oC
d) 0 K

Explanation: Heating a substance leads to faster movement of molecules due to which density decreases. Whereas, cooling a substance leads to a slower movement of molecules and occupies a smaller volume. Thus, increasing its density.

9. When is a fluid said to be ideal?
a) Non viscous and Incompressible
b) Viscous and compressible
c) Viscous and Incompressible
d) Incompressible

Explanation: Ideal fluids are fluids that have a zero viscosity. This result in a flow called as inviscid flow. Inviscid flow is non viscous and incompressible since there is no existence of shear force due to zero viscosity.

10. If a flow is having the same parameters at any given point, then it is said to be_________
a) Uniform flow
b) Quasi static flow
c) Laminar flow
d) Static flow

Explanation: A flow that takes place at a constant speed without the change in cross section is called a uniform flow. Its parameters remain a constant at any given point.

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