Explore topic-wise MCQs in Fluid Mechanics.

This section includes 185 Mcqs, each offering curated multiple-choice questions to sharpen your Fluid Mechanics knowledge and support exam preparation. Choose a topic below to get started.

101.

In which of the following processes, the heat is fully converted into work?

A. Reversible adiabatic process
B. Reversible isobaric process
C. Reversible isometric process
D. Reversible isothermal process
Answer» E.
Discussion
102.

In an adiabatic process, the work done for a given pair of end states depends on:

A. Value of index n
B. Mass of the system
C. End states only
D. Heat transferred
Answer» D. Heat transferred
Discussion
103.

For a closed system, the difference between heat added to the system and work done by the system is equal to change in

A. Entropy
B. Temperature
C. Internal energy
D. Enthalpy
Answer» D. Enthalpy
Discussion
104.

A process in which no heat is supplied or rejected from the system and entropy is not constant is known as

A. Isothermal
B. Isentropic
C. Polytropic
D. Hyperbolic
Answer» D. Hyperbolic
Discussion
105.

Maximum work by an expansion of a gas in a closed system is possible when the process takes place at constant

A. pressure
B. temperature
C. volume
D. enthalpy
Answer» B. temperature
Discussion
106.

A frictionless piston-cylinder device contains a gas initially at 0.8MPa and 0.015 m3. It expands quasi-statically at constant temperature to a final volume of 0.030 m3. The work output (in kJ) during this process will be

A. 8.32
B. 12
C. 554.67
D. 8320
Answer» B. 12
Discussion
107.

A balloon which is initially collapsed and flat is slowly filled with a gas at 100 kPa so as to form it into a sphere of 1m radius. What is the work done by the gas in the balloon during the filling process?

A. 428.9 kJ
B. 418.9 kJ
C. 420.9 kJ
D. 416.9 kJ
Answer» C. 420.9 kJ
Discussion
108.

If specific heat ratio for a gas is γ, the change in internal energy of a mass of gas at constant pressure P, when volume changes from V to 2V is,

A. \(\frac{{PV}}{{\gamma - 1}}\)
B. \(\frac{R}{{\gamma - 1}}\)
C. PV
D. \(\frac{{\gamma PV}}{{\gamma - 1}}\)
Answer» B. \(\frac{R}{{\gamma - 1}}\)
Discussion
109.

Consider the following properties:EntropyViscosityTemperatureSpecific heat at constant volumeWhich of the above properties of a system is/are extensive?

A. Only 1
B. Only 1 and 2
C. Only 2, 3 and 4
D. Only 1, 2 and 4
Answer» B. Only 1 and 2
Discussion
110.

Pressure reaches a value of absolute zero

A. At a temperature of -273 K
B. Under vacuum condition
C. At the earth’s centre
D. When molecular momentum of system becomes zero
Answer» E.
Discussion
111.

A closed system receives 60 kJ heat but its internal energy decreases by 30 kJ. Then the work done by the system is

A. 90 kJ
B. 30 kJ
C. -30 kJ
D. -90 kJ
Answer» B. 30 kJ
Discussion
112.

A rigid, insulated tank is initially evacuated. The tank is connected with a supply line through which air (assumed to be ideal gas with constant specific heats) passes at 1 MPa, 350°C. A valve connected with the supply line is opened and the tank is charged with air until the final pressure inside the tank reaches 1 MPa. The final temperature inside the tank

A. is greater than 350°C
B. is less than 350°C
C. is equal to 350°C
D. May be greater than, less than, or equal to 350°C, depending on the volume of the tank
Answer» B. is less than 350°C
Discussion
113.

In a multistage compressor, intercooling is done to

A. maximise compressor work
B. minimise compressor work
C. maximise compressor temperature
D. maximise power consumption
Answer» C. maximise compressor temperature
Discussion
114.

A heat engine is supplied with 250 kJ/s of heat at constant fluid temperature of 227°C. The heat is rejected at 27°C. The cycle is reversible, if the amount of heat rejected is

A. 273 kJ/s
B. 200 kJ/s
C. 180 kJ/s
D. 150 kJ/s
Answer» E.
Discussion
115.

Assume the above turbine to be part of a simple Rankine cycle. The density of water at the inlet to the pump is 1000 kg/m3. Ignoring kinetic and potential energy effects, the specific work (in kJ/kg) supplied to the pump is

A. 0.293
B. 0.351
C. 2.93
D. 3.51
Answer» D. 3.51
Discussion
116.

Isentropic flow is

A. Irreversible adiabatic flow
B. Reversible adiabatic flow
C. Ideal fluid flow
D. Frictionless reversible flow
Answer» C. Ideal fluid flow
Discussion
117.

In a reversible isothermal expansion process fluid expands from 10 bar and 2 m3 to 2 bar and 10 m3. During the process the heat supplied is at the rate of 100 kW. What is the rate of work done during the process

A. 20 kW
B. 35 kW
C. 80 kW
D. 100 kW
Answer» E.
Discussion
118.

For a process which is non-flow, the first law of thermodynamics states ___________

A. \( \partial U = Q - W\)
B. \(\partial U = Q + W\)
C. \(\partial H = Q - W\)
D. \(\partial H = Q + W\)
Answer» B. \(\partial U = Q + W\)
Discussion
119.

In an isentropic process, the pressure P of a gas with temperature T as P = K T5/2 where k is a constant. The ratio γ (= Cp/Cv) of the gas is:

A. 5/3
B. 9/5
C. 7/5
D. 3/2
Answer» B. 9/5
Discussion
120.

Gibb’s free energy (G) is given by

A. G = H – TS
B. \(G = \frac{H}{{TS}}\)
C. G = U – TS
D. None of these
Answer» B. \(G = \frac{H}{{TS}}\)
Discussion
121.

During a non-flow thermodynamic process (1-2) executed by a perfect gas, the heat interaction is equal to the work interaction (Q1-2 = W1-2) when the process is

A. Isentropic
B. Polytropic
C. Isothermal
D. Adiabatic
Answer» D. Adiabatic
Discussion
122.

For the steady flow of a liquid through a device, that involves no work interactions, (such as a nozzle or a pipe section) the work term is.

A. Zero
B. Maximum
C. Average
D. None of these
Answer» B. Maximum
Discussion
123.

A piston-cylinder device with air at an initial temperature of 30°C undergoes an expansion process for which pressure and volume are related as given below:p (kPa)10037.914.4V (m3)0.10.20.4The work done by the system for n = 1.4 will be

A. 4.8 kJ
B. 6.8 kJ
C. 8.4 kJ
D. 10.6 kJ
Answer» E.
Discussion
124.

An aircraft engine is an example of:

A. quasi-equilibrium
B. closed system
C. isolated system
D. open system
Answer» E.
Discussion
125.

A frictionless piston cylinder device contains 5 kg of steam at 400 kPa and 200°C. The heat is now transferred to the steam until the temperature reaches 250°C. If the piston is not attached to a shaft, its mass is constant, and by taking the values of specific volume v1 as 0.53434 m3/kg and v2 as 0.59520 m3/kg, the work done by the steam during this process is

A. 121.7 kJ
B. 137.5 kJ
C. 153.3 kJ
D. 189.1 kJ
Answer» B. 137.5 kJ
Discussion
126.

In a throttling process:

A. entropy remains the same
B. enthalpy remains the same
C. pressure remains the same
D. internal energy remains the same
Answer» C. pressure remains the same
Discussion
127.

For a process which is non-flow (U is the internal energy, Q is the heat and W is the work done) the first law of thermodynamics states ________.

A. ΔU = ∂Q - ∂W
B. \(\oint dQ + \oint dW = 0\)
C. \(\oint dQ \ne \oint dW\)
D. ΔU = ∂Q
Answer» B. \(\oint dQ + \oint dW = 0\)
Discussion
128.

In a reversible adiabatic process, the heat added (in joule) is:

A. 1.5
B. 0
C. 1
D. 2
Answer» C. 1
Discussion
129.

Internal energy is defined by

A. Zeroth law of thermodynamics
B. First law of thermodynamics
C. Second law of thermodynamics
D. Law of entropy
Answer» C. Second law of thermodynamics
Discussion
130.

85 kJ of heat is supplied to a closed system at constant volume. During the next process, the system rejects 90 kJ of heat at constant pressure while 20 kJ of work is done on it. The system is bought to the original state by adiabatic process. The initial internal energy is 100 kJ. Then what is the quantity of work transfer during the process?

A. 30 kJ
B. 25 kJ
C. 20 kJ
D. 15 kJ
Answer» E.
Discussion
131.

A 10 kg solid at 100°C with a specific heat of 0.8 kJ/kg °C is immersed in 40 kg of 20°C liquid with a specific heat of 4.0 kJ/kg °C. Estimate the temperature after a long time if the container is insulated (specific heat of water = 4.18 kJ/kg).

A. 30°C
B. 28°C
C. 26°C
D. 24°C
Answer» E.
Discussion
132.

For a simple closed system of constant composition, the difference between the net heat and work interactions is identifiable as the change in

A. Enthalpy
B. Entropy
C. Flow energy
D. Internal energy
Answer» E.
Discussion
133.

A gas is compressed frictionless from an initial state of 0.4 m3 and 0.1 MPa to a final state of 0.2 m3 and 0.1 MPa. There is a transfer of 35 kJ of heat from the gas. What is the change in internal energy (in kJ)?

A. -55
B. -15
C. 15
D. 55
Answer» C. 15
Discussion
134.

A closed system contains a simple compressible pure substance. The difference between work done by the system and heat transferred to the system is a ________ function

A. point
B. path
C. neither point nor path
D. both point and path
Answer» B. path
Discussion
135.

Assertion (A): The change in heat and work cannot be expressed as difference between the end states.Reason (R) : Heat and work both are exact differentials.

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is not a correct explanation of A.
C. A is true but R is false
D. A is false but R is true
Answer» D. A is false but R is true
Discussion
136.

Isolated system indicates

A. Mass of substance cross the boundary
B. Energy of substance cross the boundary
C. Both mass and energy of substance cross the boundary
D. Both mass and energy of substance does not cross the boundary
Answer» E.
Discussion
137.

2 kg of substance receives 500 kJ and undergoes a temperature change from 100°C to 200°C. The average specific heat of substance during the process will be

A. 5 kJ/(kg°K)
B. 2.5 kJ/(kg°K)
C. 10 kJ/(kg°K)
D. 25 kJ/(kg°K)
Answer» C. 10 kJ/(kg°K)
Discussion
138.

Heat transfer in a cyclic process are +20 kJ, -5 kJ, -10 kJ and +15kJ. Net work done for this cycle will be given by:

A. +5 kJ
B. -10 kJ
C. +20 kJ
D. -20 kJ
Answer» D. -20 kJ
Discussion
139.

A 200 W electric bulb was switched on in a 5 × 6 × 6 meter size thermally insulated room having a temperature of 50°C. The room temperature at the end of 24 hours will be

A. 145°C
B. 181.5°C
C. 135°C
D. 161.5°C
Answer» E.
Discussion
140.

A non-flow quasi-static (reversible) process occurs for which P = (-3V + 16) bar, where V is volume in m3. What is work done when V changes from 2 to 6 m3

A. 16 × 105 J
B. 16.5 × 105 J
C. 16 × 103 J
D. 16.5 × 102 J
Answer» B. 16.5 × 105 J
Discussion
141.

A stationary mass of gas is compressed without friction from an initial state of 0.3 m3 and 0.105 MPa to a final state of 0.15 m3 and 0.105 MPa, the pressure remaining constant during the process. There is a transfer of 37.6 kJ of heat from the gas during the process. The internal energy of the gas changes by

A. -21.85 kJ
B. 3.85 kJ
C. -37.6 kJ
D. -15.75 kJ
Answer» B. 3.85 kJ
Discussion
142.

1 m3 of air at a pressure of 10 kg/cm2 is allowed to expand freely to a volume of 10 m3. The work done will be

A. +ve
B. -ve
C. zero
D. 105 kg-m
Answer» D. 105 kg-m
Discussion
143.

A closed system is one in which ______.

A. Mass does not cross boundaries of the system, though energy may do so
B. Mass crosses the boundary but not the energy
C. Neither mass nor energy crosses the boundaries of the system
D. Both energy and mass cross the boundaries of the system
Answer» B. Mass crosses the boundary but not the energy
Discussion
144.

An insulated rigid vessel contains a mixture of fuel and air. The mixture is ignited by a minute spark. The contents of vessel experience

A. increase in temperature, pressure and energy
B. decrease in temperature, pressure and energy
C. increase in temperature and pressure but increase in energy
D. Increase in temperature and pressure but no change in energy
Answer» E.
Discussion
145.

Heat exchange takes place, in which the product of pressure and volume remains constant, is known as:

A. Hyperbolic process
B. Isothermal process
C. Adiabatic process
D. Isentropic process
Answer» C. Adiabatic process
Discussion
146.

If 2 bar of air at 27°C is heated to 177°C at constant volume, the pressure will be

A. 6.56 bar
B. 3 bar
C. 9 bar
D. 13.11 bar
Answer» C. 9 bar
Discussion
147.

In a reversible adiabatic process the ration \(\left( {\frac{{{T_1}}}{{{T_2}}}} \right)\) is equal to:

A. \({\left( {{v_1}{v_2}} \right)^{\frac{{\gamma - 1}}{\gamma }}}\)
B. \({\left( {\frac{{{v_1}}}{{{v_2}}}} \right)^{\frac{{\gamma - 1}}{\gamma }}}\)
C. \({\left( {\frac{{{p_1}}}{{{p_2}}}} \right)^{\frac{{\gamma - 1}}{\gamma }}}\)
D. \({\left( {\frac{{{p_2}}}{{{p_1}}}} \right)^\gamma }\)
Answer» D. \({\left( {\frac{{{p_2}}}{{{p_1}}}} \right)^\gamma }\)
Discussion
148.

Air at 27 °C and 100 kPa enters in a steady flow to a nozzle at a velocity of 100 m/s. If the inlet area of the nozzle is 0.5 m2, what is the mass flow rate through the system?

A. 116 kg/s
B. 232 kg/s
C. 58 kg/s
D. 143 kg/s
Answer» D. 143 kg/s
Discussion
149.

An open system

A. is a specified region where transfers of energy and/or mass take place
B. is a region of constant mass and only energy is allowed to cross the boundaries
C. cannot transfer either energy or mass to or from the surroundings
D. has an enthalpy transfer across its boundaries and the mass within the system is not necessarily
Answer» B. is a region of constant mass and only energy is allowed to cross the boundaries
Discussion
150.

A 2 kg of steam occupying 0.3 m3 at 15 bar is expanded according to the law pv1.3 = constant to a pressure of 1.5 bar. The work done during the expansion will be

A. 602.9 kJ
B. 606.7 kJ
C. 612.5 kJ
D. 618.3 kJ
Answer» E.
Discussion