# UNIT 1 Fluid and Bernoulli’s Equation Important Questions with solution in Fluid Mechanics & Fluid Machines AKTU

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Important Questions For Fluid Mechanics & Fluid Machines :
*Unit-01     *Unit-02
*Unit-03    *Unit-04
*Unit-05    *Short-Q/Ans
*Question-Paper with solution 21-22

## Discuss some physical properties of fluids in brief?

These are a few of the physical characteristics of fluids:

a. Density or Mass Density:

1. It can be described in terms of mass per unit volume under constant pressure and temperature. It is also known by the name specific mass. It is denoted by p and its unit is kg/m3.

b. Weight Density:

1.It can be characterized as the mass per unit volume at standard pressure and temperature. It also goes by the name “specific weight.” It is denoted by W and its unit is N/m3.

c. Specific Volume:

1. It is defined as the volume per unit mass of fluid

d. Specific Gravity:

It is the ratio of the specific weight of the given fluid to the specific weight of a standard fluid.

For liquids, standard fluid is pure water at 4 °C and air is standard fluid for gases.

e. Viscosity:

1. It is described as a fluid’s characteristic that affects how resistant it is to shearing forces. Pa-s is its SI unit and poise is its CGS unit.

2. An ideal fluid has no viscosity.

3. Viscosity of fluids is due to cohesion and adhesion.

## Explain the following a. Compressibility, b. Surface tension, and C. Incompressible flow.

a. Compressibility

1. Compressibility is the quality that allows fluids to alter in volume when subjected to external pressure.

2. It is the volumetric strain divided by the compressive stress, which is known as the reciprocal of the bulk modulus of elasticity.

b. Surface Tension:

1. It is described as the tensile force acting between two immiscible liquids or on the surface of a liquid in contact with a gas.

2. It is denoted by sigma (o) and its SI unit is N/m.

3.This occurs due to the force of cohesion at the free surface as shown in Fig. 1.6.1.

4.Consider a liquid molecule that is in equilibrium and is surrounded by other molecules on all sides.

5.There are no liquid molecules above the surface of a liquid’s free surface to counteract the force of the molecules below it.

6.As a result, the molecule experiences a net inward force that is normal to the surface.

7. As a result, a tiny layer of molecules forms at the free surface, acting as a membrane that allows a thin, little needle to float there.

c. Incompressible Flow:

1.It is that type of flow in which the density is constant for the fluid flow.

2. Isochoric flow, which meaning in the same place or space, is another name for incompressible flow.

3. Since the temperature and pressure of liquids and gases do not change in incompressible flow, these types of flow are simple to model.

## Suggest the device used for the measurement of fluid flow through ducts or pipes. Explain them.   OR What are the various applications of Bernoulli’s equation ? Explain them.

Some of the simple applications of Bernoulli’s equation are as follows:

A Venturimeter:

1. A venturi metre is a tool used to gauge the flow rate of a fluid via a pipe.

2. It consists of three parts, as given below :

i. A short converging part,

ii. Throat, and

ii. Diverging part.

It works on the principle of Bernouli’s theorem.

4. As shown in Fig. 1.12.1, a venturimeter is fitted in a horizontal pipe through which a fluid is flowing.