Different types of pressure

Fluid pressure -:  Pressure is transmitted with equal intensity in all directions and act normal to any plane is known as fluid pressure .

Difference in pressure between any two points at different level in a liquid is equal to = unit weight of liquid × difference in elevation. 

Gauge pressure -: It is equal to unit weight of the liquid multiplied by the height of the desired point above free surface . Gauge pressure represents pressure above atmospheric pressure. 

Bar pressure -: Gauge pressure in bar is generally obtained by dividing the gauge pressure in Pascal Z by 10^5 .

Pressure head-: Pressure head 'h' represent the height of a volumn of homogeneous fluid that will produce a given intensity of the pressure   ( h = p / ρg ) .

Fluid mechanics MCQ-07

Q.1 Gas is a ______ fluid. 

A. Compressible 

B. Non - compressible 

C. Viscous 

D. Non- viscous 

Ans-: A

Q.2 The ratio of the mass of a body to the mass of an equal volume of a substance taken as a standard known as ___.

A. Kinematic viscosity 

B. Relative density 

C. Density

D. Viscosity 

Ans-:B

Q.3 The rise or fall of a liquid in a capillary tube caused by the surface tension called ?

A. Rise of liquid 

B. Fall of liquid 

C. Capillarity 

D. A+B

Ans-: C

Q.4 The fluid such as air for which the density is not a single-valued function of the pressure is known as ?

A. Barotropic fluid 

B. Nonbarotropic fluid 

C. Real fluid 

D. Perfect fluid 

Ans-:B

Q.5 Buoyant force is equal to _____.

A. Force exerted by body

B. Volume of liquid displaced 

C. Force exerted in body

D. Weight of the body 

Ans-: B

Q.6 Stanton tube is used to measure which of the following?

A. Shear strain

B. Shear stress in fluid 

C. Shear strain in fluid 

D. Pressure of fluid 

Ans-: B

Q.7 What is the density of air ?

A. 11.2 kg/m^-3

B. 1.24 kg/m^3

C. 1.24 kg/m^-3

D.  12.4 kg/m^3

Ans-: C

Q.8 Whether stream function exists for which type of flow?

A. Uniform flow 

B. One dimensional flow 

C. Turbulent flow 

D. Two dimensional flow 

Ans-: D

Q.9 What is the value of density of mercury?

A. 1360 kg/m^-3

B. 13600 kg/m ^-3

C. 14000 kg/m^3

D. 13560 kg/m^-3

Ans-: B

Q.10 The square root of ratio inertia force to gravity force is called ?

A. Real number

B. Froude number

C. Reynolds number 

D. None of these 

Ans-: B

Q.11 When specific mass flow is not able to take place in a pipe line us called ?

A. More pressure in pipe line 

B. Choking in pipe line 

C. Disturbance in flow

D  None of these 

Ans-: B

Q.12 Maning's formula is used to measure?

A. Viscosity of fluid

B. Velocity if fluid in pipe 

C. Pressure of fluid in a pipe 

D. Surface tension 

Ans-: B

Q.13 Velocity potential is which type of quantity.

A. Dimensional

B. Scalar

C. Non - scalar

D. None of the above 

Ans-: B

Q.14 In open channel maximum velocity occurs at ______.

A. Center of the channel 

B. Top of the channel

C. Near Bottom of the channel 

D. First point of the channel 

Ans-: C

Q.15 Velocity is zero at which point ?

A. Stagnation point 

B. Triple point 

C. Critical point

D. None of the above 

Ans-: A

Fluid mechanics basic

Fluid  -: A fluid is a substance that is capable of flowing , conform to shape of containing vessel. It also deforms continuously when it issubjected to even a smallest shear stress.

An ideal fluid is frictionless and also it is incompressible .

Viscosity-:It is the property of fluid by virtue of which it offers resistance to shear. Viscosity is caused by cohesive for between molecules of liquid and by collision between molecules of gas .Viscosity is practically independent of pressure and depend upon temperature only .

Unit of viscosity " poise " or 1 gm /cm/ sec.

( 1 poise = 0.1 Ns/ m^2 )

Kinematic viscosity -: It is the ratio of dynamic or absolute viscosity and density. It's unit is stoke . Stoke is equal to 1cm^2/sec.

Newton's law of viscosity -: newton's law of viscosity state that shear stress  ( between  adjacent layer of fluid) is directly proportional to velocity gradient. 

Shear stress = 𝝁 du / dx

( 𝝁 = coefficient of viscosity Pa sec or Ns/ m^2)

du/dx is known as velocity gradient or rate of shear strain and it is zero for fluids at rest.                                                                                          Fluid following newton's law of the viscosity is known as Newtonian fluids and other non - Newtonian fluids. An ideal fluid offers no resistance to flow but real fluid does.

( viscosity is zero for ideal fluid but not for real fluid. )

Surface tension -:                                                                   Liquid molecules are attracted to each other by equal forces in all directions. On the surface they are subjected to an inward attraction which us not balanced by the outward attraction. This cause the liquid surface to seek a minimum possible area due to surface tension. 

Surface tension is also expressed as force per unit length .