# Fluid Mechanics Questions and Answers – Introduction to Fluid Mechanics

This set of Fluid Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Introduction to Fluid Mechanics”.

1. Which one is in a state of failure?
a) Solid
b) Liquid
c) Gas
d) Fluid

Explanation: A fluid is a Tresca material with zero cohesion. In simple words, fluid is in a state of failure.

2. A small shear force is applied on an element and then removed. If the element regains it’s original position, what kind of an element can it be?
a) Solid
b) Liquid
c) Fluid
d) Gaseous

Explanation: Fluids (liquids and gases) cannot resist even a small shear force and gets permanently deformed. Hence, the element must be a solid element.

3. In which type of matter, one won’t find a free surface?
a) Solid
b) Liquid
c) Gas
d) Fluid

Explanation: Solid molecules have a definite shape due to large inter-molecular forces. In liquids, molecules are free to move inside the whole mass but rarely escape from itself. Thus, liquids can form free surfaces under the effect of gravity. But, in case of gases, molecules tend to escape due to low forces of attraction. Thus, gases won’t form any free surface.

4. If a person studies about a fluid which is at rest, what will you call his domain of study?
a) Fluid Mechanics
b) Fluid Statics
c) Fluid Kinematics
d) Fluid Dynamics

Explanation: Fluid Mechanics deals with the study of fluid at rest or in motion with or without the consideration of forces, Fluid Statics is the study of fluid at rest, Fluid Kinematics is the study of fluid in motion without consideration of forces and Fluid Dynamics is the study of fluid in motion considering the application forces.

5. The value of the compressibility of an ideal fluid is
a) zero
b) unity
c) infinity
d) more than that of a real fluid

Explanation: Ideal fluids are incompressible which means they will have zero compressibility.

6. The value of the Bulk Modulus of an ideal fluid is
a) zero
b) unity
c) infinity
d) less than that of a real fluid

Explanation: Bulk modulus k is the reciprocal of compressibility fi.
k = 1fi
Ideal fluids are incompressible which means fi = 0. Thus, k will be infinity.

7. The value of the viscosity of an ideal fluid is
a) zero
b) unity
c) infinity
d) more than that of a real fluid

Explanation: Ideal fluids are non-viscous which means they will have zero viscosity.

8. The value of the surface tension of an ideal fluid is
a) zero
b) unity
c) infinity
d) more than that of a real fluid

Explanation: Ideal fluids haze zero surface tension but real fluids have some finite value of surface tension.

Sanfoundry Global Education & Learning Series – Fluid Mechanics.