# 500+ Applied Thermodynamics (AT) Solved MCQs

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1.

## Aim of engine testing is

A. to get specified information
B. to justify rating of engine
C. to validate design data
D. all the above
Answer» D. all the above
2.

## Heat losses in an engine are indicative of

A. thermal efficiency of engine
B. indicated power
C. brake power
D. none of the above
Answer» A. thermal efficiency of engine
3.

## Power developed within the cylinder is called

A. i.p.
B. b.p.
C. f.p.
D. unavailable power
4.

## Power available at output shaft is called

A. i.p.
B. b.p.
C. f.p.
D. unavailable power
5.

A. b.p/i.p
B. i.p./b.p
C. i.p./b.p.
D. b.p./i.p
6.

## Best method to measure indicated mean effective pr (imep) is by

A. mechanical indicator
B. electronic indicator
C. electrical indicator
D. all are equal efficient
Answer» B. electronic indicator
7.

A. imep
B. speed
C. temperature
D. f.p.
8.

A. p-v
B. p-t
C. t-v
D. t-p
9.

## Mechanical indicators are suitable to measure imp in case of

A. low speed engine up to 1500 rpm
B. medium speed engines (1500-3000)
C. high speed engines more than 3000 rpm
D. none of the above
Answer» A. low speed engine up to 1500 rpm
10.

## If a= net area of diagram in mm², l= length of indicator diagram in cm & k= spring constant in N/m²/m the imp in bar equals

A. (a/l)xk
B. (a/l) x k x 10ˉ⁹
C. (a/l) x k x 10ˉ⁶
D. (a/l) x k x 10ˉ³
Answer» B. (a/l) x k x 10ˉ⁹
11.

A. bmep
B. imep
C. b.p
D. i.p
12.

## If work developed by the engine per cycle is W, then the indicated mean effective pr equals to

A. w
B. w / stroke volume
C. w / length of stroke
D. w x stroke volume
Answer» B. w / stroke volume
13.

## Best method to measurement of B.P. is

A. rope brake dynamometer
B. prony brake dynamometer
C. hydraulic dynamometer
D. all are equal
Answer» C. hydraulic dynamometer
14.

## Which of the dynamometer cannot be used for measurement of B.P. at high speeds

A. prony brake
B. hydraulic
C. swing field
D. none of the above
Answer» A. prony brake
15.

## Which of the following dynamometer is suitable to measure B.P. of an aircraft

A. prony brake
B. hydraulic
C. swinging field
D. eddy current
Answer» D. eddy current
16.

A. increases
B. remains same
C. decreases
D. can not say
17.

## Which is the best way to measure F.P. of an I.C., engine

A. willan\s line method
B. morse test
C. motoring test
D. all are the equal effective
Answer» B. morse test
18.

## Willan's line method for determining F.P. is applicable to

A. c.i engines
B. engine runs at constant speed
C. both a & b
D. none of the above
Answer» C. both a & b
19.

## I.P. of engine can be determined by

A. willan\s line method
B. morse test
C. motoring test
D. none of the above
Answer» B. morse test
20.

## Increase in F.P. of an engine causes

A. reduced b.p.
B. increased cooling load
C. increased s.f.c.
D. all the above
Answer» D. all the above
21.

## Morse test in multi cylinder engine is used to determine

A. mechanical efficiency
B. thermal efficiency
C. air standard l efficiency
D. relative l efficiency
Answer» A. mechanical efficiency
22.

## Which is assumed constant in determining F.P. by Willan's line method.

A. mechanical efficiency
B. beake thermal efficiency
C. indicated thermal efficiency
D. none of the above
Answer» C. indicated thermal efficiency
23.

A. 0-30%
B. 30-50%
C. 70-80%
D. 90-100%
24.

## The measurement of frictioned power by Willans line is applicable only to

A. c.i engine at a particualr speed
B. s.i engine at a particular speed
C. any engine at a particular speed only
D. none of the above
Answer» A. c.i engine at a particualr speed
25.

## morse test is applicable only to

A. single cylinder c.i engines
B. single cylinder s.i engine
C. multi cylinder c.i engine
D. single and multi cylinder c.i and s.i engine
Answer» C. multi cylinder c.i engine
26.

## the most accurate method of determining friction power is by

A. willins line
B. morse test
C. motoring test
D. measurement of brake and indicated power
Answer» D. measurement of brake and indicated power
27.

## in the air base method of measuring air flow, the air base is provided to

A. damp out the pulsations
B. have constant temprature
C. have constant flow
D. provide constant velocity of flow
Answer» C. have constant flow
28.

A. 10-100%
B. 200-300%
C. 500-600%
D. 10
29.

## the best method of measuring speed is by

A. mechanical tachometer
B. electric tachometer
C. magnetic pickup
D. none of the above
Answer» A. mechanical tachometer
30.

A. hc
B. co
C. nox
D. co2
31.

A. hc
B. co
C. nox
D. co2
32.

## non dispersive infrared analyzer is widely accepted instrument for measuring

A. unburned hydrocarbons
B. carbone monoxide
C. carbone dioxide
D. nox
Answer» B. carbone monoxide
33.

A. n/2
B. n
C. 2n
D. 4n
34.

A. n/2
B. n
C. 2n
D. 4n
35.

## mechanical effficiency is the ratio of

A. frictional power to brake power
B. frictional power to indicated power
C. brake power to indicated power
D. indicated power ot frictional power
Answer» C. brake power to indicated power
36.

## volumetric efficiency is a measure of

A. power of the enigne
B. speed of the engine
C. brathing capacity of the engine
D. pressure rise in the cylinder
Answer» C. brathing capacity of the engine
37.

## thermal efficiency varries

A. inversely as specific fuel consumption
B. directly as specific fuel consumption
C. as square as specific fuel consumption
D. as root as specific fuel consumption
Answer» A. inversely as specific fuel consumption
38.

## the spark timing and combustion rate should be should be such that

A. one half of the total pressure occurs at tdc
B. ignition delay is reduced
C. peak pressure occurs at tdc
D. none of the above
Answer» A. one half of the total pressure occurs at tdc
39.

## indicated power is directly proportional to

A. air consumption
B. torque
C. cylinder peak pressure
D. none of the above
Answer» A. air consumption
40.

## the brake thermal efficiecny of SI engine is in the range of

A. 35%-60%
B. 25%-35%
C. 60%-80%
D. none of the above
41.

## the boiling point of a four cylinder engine is 30 with all cylinder firing and 20 with one cylindr cut

A. 0.6
B. 0.75
C. 0.8
D. none of the above
42.

A. 5 bar
B. 7-6bar
C. 10bar
D. 15bar
Answer» A. 5 bar
43.

A. 30-40%
B. 40-60%
C. 60-70%
D. 75-90%
44.

## if the performance of SI engine manufacturer having different capacities sizes and system are to be compared , the common parameter would be

A. engine cylinder diameter
B. b.h.p
C. speed
D. mean effective pressure
Answer» D. mean effective pressure
45.

## mores test is conducted on

A. single cylinder c.i engines
B. multi cylinder engine
C. vcc engine
D. horizontle engine
Answer» B. multi cylinder engine
46.

A. 100hrs
B. 200hrs
C. 400hrs
D. 500hrs
47.

## which of the following factor will not assist in improving thermal efficiency of a compression ignition engine

A. fine atomisation and even distribution of fuel
B. miniumum heat loss during combustion
C. clear exhaust
D. high surgace to volume ratio
Answer» D. high surgace to volume ratio
48.

## which statement is correct

A. morese test can be conducted on petrol engine
B. morese test can be conducted on diesel engine
C. morese test can be conducted only on multicylinder engine
D. morese test can be conducted on crf engine
Answer» C. morese test can be conducted only on multicylinder engine
49.

## rope brake dynamometer falls under the category of

A. hydraulic dynamometer
B. transmission type dynamometer
C. mechanical friction type dynamometer
D. torsion type dynamometer
Answer» C. mechanical friction type dynamometer
50.

## prony brakes are used for testing

A. small engine
B. large capasity engine
C. highspeed engine
D. slow speed engine
Answer» A. small engine
51.

## which of the following is performed for supercharging of ic engine

A. roots blower
B. axial compressor
C. sliding vane type compressor
D. reciprocationg compressor
Answer» B. axial compressor
52.

## from the engine indicator diagram we obtain

A. indicatecd mean effective pressure
B. brake mean effective pressure
C. mechanical efficiency
D. relative efficiecy
Answer» A. indicatecd mean effective pressure
53.

## the more accurate dynamometer is

A. prony brake type
B. hydraulic type prony
C. swinging field type
D. eddy current type
Answer» A. prony brake type
54.

## the most commonly used dynamometer on account of its simplicity of construction is the

A. brake type
B. hydraulic type prony
C. swinging field type
D. eddy current type
Answer» A. brake type
55.

## brake mean effective pressure in an engine depends upon its

A. speed only
B. torque only
C. speed and torque
D. speed and power
Answer» B. torque only
56.

A. 25-30%
B. 30-60%
C. 60-80%
D. more then 80%
57.

## the brake power is the

A. power availabale at the output of the shaft
B. energy developed inside the cylinder block
C. energy lost dude to friction
D. none of the above
Answer» A. power availabale at the output of the shaft
58.

## the total power developed by the combustion of the fuel is

A. bp
B. ip
C. fp
D. none of the above
59.

## mean effective pressure is the pressure

A. pressure acting on the crank shaft
B. which is acting on the piston through out the power stroke
C. pressure required to inject the fuel in the combustion chamber
D. none of the above
Answer» B. which is acting on the piston through out the power stroke
60.

## fuel air ratio is

A. mass of fuel to mass of air
B. reciprocal of air fuel ratio
C. which affects the combustion phenomenon
D. all of the abov e
Answer» D. all of the abov e
61.

## specific fuel consumption is

A. amount of fuel consumed per unit power developed per hour
B. amount of fuel consumed per unit indicated power developed per hour
C. amount of fuel consumed per hour
D. all of the above
Answer» A. amount of fuel consumed per unit power developed per hour
62.

## heat balance sheet indicates

A. amount of heat energy consumed in the combustion chamber
B. brake up of the total energy input in to different parts
C. amount of energy lost through the exhaust
D. all of the above
Answer» B. brake up of the total energy input in to different parts
63.

## the frictional power is

A. bp+ip
B. bp-ip
C. bpxip
D. none of the above
64.

## identify the correct statement

A. power friction means less brake power
B. lower friction means high barke power
C. higher friction means high brake power
D. none of the above
Answer» B. lower friction means high barke power
65.

## power out put of an engine can be increased by

A. speed
B. compression ratio
C. use of two stroke cycle
D. all of the above
Answer» D. all of the above
66.

## power out put of an engine can be increased by

A. speed
B. charge density
C. compression ratio
D. all of the above
Answer» D. all of the above
67.

## increasing the power out put by increasing the compression ratio is limited by

A. weight to power ratio
B. utilization of energy in fuel
C. air fuel ratio
D. hucr
68.

## increase in speed to improve B.P is limited by

A. maximum volumetric efficienccy
B. robust engine
C. fuel suply
D. all of the above
Answer» D. all of the above
69.

A. increases
B. remains same
C. decreases
D. can not say
70.

## increase in charge density will

A. increases volumetric efficiency
B. power out put
C. both a & b
D. none of the above
Answer» C. both a & b
71.

## supercharging is a process of increasing the

A. pressure in the cylinder
B. suction pressure of charge
C. temprature of the charge
D. charge density
Answer» D. charge density
72.

## supercharging is essential for

A. stationary engine
B. marine engine
C. aircraft engine
D. none of the above
Answer» C. aircraft engine
73.

## power out put of static engine at high alitude compared to power out put at sea level is

A. higher
B. lower
C. same
D. can not predict
Answer» D. can not predict
74.

## objective of superchargin are

A. increase power output
B. reduces weight to power ratio
C. compansate loss of power at high altitudes
D. all of the above
Answer» D. all of the above
75.

## which is not the objectve of supercharging

A. to increase power out put
B. to increase weight to power ratio
C. to increase charge density at high alitude
D. none of the above
Answer» B. to increase weight to power ratio
76.

## an exhaust gas driven blower/ compressor to increase charge density is called

A. supercharger
B. turbocharger
C. both a & b
D. none of the above
Answer» D. none of the above
77.

## a blower/compressor driven by engine shaft to increase charge density is called

A. supercharger
B. turbocharger
C. both a & b
D. none of the above
Answer» D. none of the above
78.

A. more
B. same
C. less
D. can not say
79.

## which is not a supercharger

A. centrifugal compressor
B. root blower
C. vane blower
D. pump
80.

## compressed air of turbochar is cooled in aftercooler before supply to engine because it

A. reduceses density of air
B. increases volumetric efficiency
C. increases density of air
D. both b and c
Answer» D. both b and c
81.

## efficiency of turbocharged engine compared to naturally aspirated engine is

A. more
B. same
C. less
D. can not predict
Answer» D. can not predict
82.

## a free piston engine has

A. gear driven supercharger
B. a turbocharger
C. coupled engine, compressor and turbine supercharge
D. gear driven supercharger and separate power turbine
Answer» D. gear driven supercharger and separate power turbine
83.

## Reason for not using very high suction pressure in an engine with the help of supercharger / turbocharger are

A. increased weight
B. increased detonation in si engine
C. increased fp and bearing load
D. all of the above
Answer» D. all of the above
84.

## Reason for not using very high suction pressure in an engine with the help of supercharger / turbocharger are

A. high mean wall and exhaust gas temprature
B. increased detonation in si engine
C. increased weight
D. all of the above
Answer» D. all of the above
85.

## superchargin is usually is not employed in si engine in the following cases

A. static or mobile enigne
B. static engine at high altitude
C. aero enignes at the time of take off
D. none of the above
Answer» A. static or mobile enigne
86.

## superchargin in ci engine is limited by

A. peak pressure and temprature in cylinder
B. mean cylinder wall tempratuer
C. load on bearing and fuel economy
D. all of the above
Answer» C. load on bearing and fuel economy
87.

## A theory in which chain carriers are formed in one step and destroyed in the next step relate to the theory of combustion as

A. preferencial burning of carbon
B. chain reaction theory
C. hydroxylation theory
D. none of the above
Answer» B. chain reaction theory
88.

## Time interval between instant the spark is given and the point a tiny flame appears is called

A. igniton lag
B. ignition delay period
C. ignition delay angle
D. either \a\ or b\
Answer» D. either \a\ or b\
89.

## Angle tuned by crank between the point of spark and formation of flame is called

A. igniton lag
B. ignition delay period
C. ignition delay angle
D. either \a\ or b\
Answer» C. ignition delay angle
90.

## In a vertical engine, the crank angle before TDC at the instant spark is given is called

A. igniton lag
B. ignition delay period
C. ignition delay angle
D. angle of spark advance
91.

## The travel of flame speed (m/s) in the S.I. combustion chamber is approximately

A. 5 to 15
B. 15 to 35
C. 35 to 50
D. > 50
Answer» B. 15 to 35
92.

## Ignition lag in S.I. engine reduces due to

A. increase in pressure,temperature and compression ratio
B. decrease in pressure,temperature and compression ratio
C. decrease in residual gases
D. both a and c
Answer» D. both a and c
93.

## Minimum ignition lag is obtained when

A. rich mixture(5 to 10%)
B. stoichiometric mixture
C. lean mixture
D. very rich mixture(15 to 30%)
Answer» A. rich mixture(5 to 10%)
94.

## Ignition delay period with increase in speed

A. increases
B. decreases
C. remains same
D. none of the above
Answer» C. remains same
95.

## Ignition delay angle________with increase in speed

A. increases
B. decreases
C. remains same
D. none of the above
96.

## The speed of the flame propagation increases with increase in

A. compression ratio
B. suction pressure and temperatur
C. slightly rich mixtures
D. all of the above
Answer» D. all of the above
97.

## Increase in turbulence________the flame speeds

A. increases
B. decreases
C. doesn\t affect
D. none of the above
98.

## Increase in speed of the engine________the flame speeds

A. increases
B. decreases
C. doesn\t affect
D. none of the above
99.

## Increase in the size of similar engines__________the crank angle turned during flame travel across the cylinder

A. increases
B. decreases
C. doesn\t affect
D. none of the above
Answer» C. doesn\t affect
100.

## Flame speed in combustion chamber during flame travel are

A. high at beginning and at the end whereas low in the middle
B. low at beginning and end and high in the middle
C. constant throught
D. cannot predict
Answer» B. low at beginning and end and high in the middle