Free energy and free Enthalpy

Free energy -: Free energy ( or Helmholtz function) is defined as  f = u - Ts .

It is equal to the work during a constant- volume isothermal reversible nonflow process .

Free Enthalpy -: Free enthalpy ( or Gibbs function ) is defined as  g = h - Ts

Where , u = internal energy  h = enthalpy ,      T = temperature, s = entropy 

Gibbs function is of particular importance in processes where chemical changes occur. For reversible isothermal steady flow pro-cesses or for reversible constant- pressure isothermal nonflow processes , change in free energy is equal to net work .

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 MCQ-06

Q.1 Center of pressure on a inclined plane is ________ .

A. Above the centroid

B. Below the centroid 

C. At the centroid 

D. None of these 

Ans-: B

Q.2 The unit of dynamic viscosity is ___.

A. M^2 per second 

B. Newton sec per m^2

C. Newton sec per m^3

D. Kg sec / meter

Q.3 Spherical shape of the rain drop are due to ___.

A. Surface tension 

B. Viscosity 

C. Density 

D. None of the above 

Ans-: A

Q.4 The inside and outside pressure diffe-rence between inside and outside of water drop is ______.

A. P = T/r

B. P = 2T/r

C. P = T×r

D. 0

Ans-: B

Q.5 Which devise is used to measure very low pressure?

A. Thermometer 

B. Manometer

C. Piezometer

D. None of these 

Ans-: C

Q.6 Surface tension of water at 20°C is ___.

A. 60.71

B. 60.61

C. 52.23

D. 79.61

Ans-: A

Q.7 Due to balance of the body weight and the buoyancy force a floating body ______.

A. Submerged in water 

B. Partially submerged 

C. Floating 

D. None of these 

Ans-: B

Q.8 General energy equation holds for which type of flow?

A. Laminar flow 

B. Uniform flow 

C. Non- uniform flow 

D. Steady flow 

Ans-: C

Q.9 Hydraulic grade line may be above or below the centre line of conduit.

A. Yes 

B. No 

C. At specific pressure 

D. None of these 

Ans-: A

Q.10 During the opening of a valve in a pipe line ,the flow is ______.

A. Steady 

B. Unsteady 

C. Uniform 

D. Turbulent 

Ans-: B

Fluid mechanics MCQ -05

Q.1 For which type of flow Bernoulli's theo-rem is applicable?

A. Turbulent flow 

B. Laminar flow 

C. Perfect incompressible fluid flowing in a continuous stream

D. Normal flow

Ans-: C

Q.2 Velocity of flow in open channel is determined by which equation?

A. Chezy's equation 

B. Bernoulli equation 

C. Motion equation 

D. None of these 

Ans-: A

Q.3 The magnitude of the water hammer is depend on the _______ .

A. Rate of stoppage of flow

B. Length of the pipe

C. Elastic properties of pipe material 

D. All of the above 

Ans -: D

Q.4 At the center of the pipe velocity of fluid particles is _____.

A. Zero

B. Maximum 

C. Minimum 

D. One

Ans-: B

Q.5 100 kN/m^2 is equal to _____ .

A. 100 mm of water column

B. 10 mm of water column

C. 20 mm of water column 

D. 200 mm of water column

Ans-: B

Q.6 The flow in venturiflume take place at ___.

A. Vacuum 

B. Atmospheric pressure 

C. High temperature 

D. High pressure 

Ans-: B

Q.7 Bernoulli theorem deals with the conser-vation of hydraulic pressure .

A. Yes 

B. No 

C. At high pressure 

C. At 0° C 

Ans-: A

Q.8 The volume of water which flows thro-ugh a section of a channel per second is known as __.

A. Flow rate

B. Discharge 

C. Stream flow 

D. None of these 

Ans-: B

Q.9 The pattern obtained by the intersection of stream lines and potential lines is called _.

A. Flow pattern

B. Flow design

C. Flow net

D. Flow rate 

Ans-: C

Q.10 The force exerted on a body by a static fluid in which it is submerged or floating called ______ force .

A. Buoyant force

B. Drag force

C. Impact load 

D. Submerged force

Ans-: A

Fluid mechanics MCQ-04

Q.1 which instrument is used to measure flow ?

A. Thermometer 

B. Rotameter

C. Raynold's meter

D. Barometer

Ans-: B

Q.2 Hydraulic jump is the example of which type of flow ?

A. Uniform flow 

B. Steady flow 

C. Non- uniform flow 

D. Turbulent flow 

Ans-: C

Q.3 Any obstruction of a stream flow over which water flows can be called ___.

A. Weir

B. Spillway

C. Water hammer

D. None of these 

Ans-: A

Q.4 water hammer is caused due to sudden stoppage of ____ .

A. Water contain in a tank

B. Water flow in a pipe 

C. Water flow through open channel 

D. All of the above 

Ans-: B

Q.5 _____ are used to relieve the pipe line of excessive pressure. 

A. Dam

B. Surge tank 

C. Hydraulic dam

D. None of these 

Ans-: B

Q.6 which device is used for measuring the rate of flow of a liquid through a small channel?

A. Notch

B. Rotameter 

C. Manometer

D. NOT

Ans-: A

Q.7 which of the following is measured by the pitot tube?

A. Pressure 

B. Flow

C. Discharge 

D. Velocity 

Ans-: D

Q.8 the upper surface of the weir over which water flows ______.

A. Vein

B. Sill

C. Nappe

D. Weir top surface 

Ans-: B

Q.9 specific gravity of fluid is determined by 

A. Hydrometer

B. Rotameter 

C. Manometer

D. None of these 

Ans-: A

Q.10 An idel fluid is __.

A. Frictionless 

B. Incompressible 

C. Very viscous 

D. A+B

Ans-: D

Hydraulic jump and water hammer

Hydraulic jump -:It is occurs when rapidly flowing of liquid in an open channel sudde- nly changes to a slowly flowing stream with a large cross - section area and sudden rise in elevtaion of liquid surface occurs. It is a very effective device for creating irrever- sibilities and commonly used at the end of chutes or the bottom of spillway to destroy much of kinetic energy in flow.this is the example of steady non- uniform flow. 

Water hammer-: water hammer is sudden stoppage result in a pressure wave which moves upstream with velocity of sound in the medium which is reflected back and fourth until dissipated by friction and im-perfect elasticity. Water hammer is caused due to sudden stoppage of water flow in a pipe .

Rise of pressure (p) due to sudden stopping of flow in a pipe is -

P = v / √ g/w ( 1/k +D/tE )

V = velocity of flow in pipe of diameter D , 

thikness t and coefficient of elasticity E

K = coefficient of bulk modulus of fluid, and

w = specific weight of fluid .

Hydraulic coefficient

Orifice -: orifice is a smaller opening of the side or at bottom of a tank . Mouthpiece is a short length of pipe is 2-3 times of it's dia-meter in length fitted in a tank of vessel con- taining the fluid. 

The various types of hydraulic coefficient 

1. Coefficient of velocity -: The ratio of the velocity of the jet at vena-contracta to the theoretical velocity is known as coefficient of velocity. In the terms of coordinates ( a,b) for vena-contracta, Cv = a / √4bH .

H = Height of fluid in the tank.

The average value of  coefficient of velocity is 0.97.

2. Coefficient of discharge -: coefficient of discharge iss the ratio of the actual discharge through or orifice to theoretical discharge. 

0.62 is the average value of the coefficient of discharge. 

3. Coefficient of resistance -: The coefficient of resistance is treated equal to zero for all the practical purpose. The ratio of the loss of head in the orifice to the head of water available at the orifice exist is known as the coefficient of resistance. 

4. Coefficient of contraction-:Coefficient of contraction is the ratio of the area of the jet at vena-contracta to the area of the orifice opening. The average value of the coefficient of contraction is 0.64 .