50+ Mechanical Engineering Solved MCQs

1.

The range of mechanical efficiency for automobile is

A. 0-30%
B. 30-50%
C. 70-80%
D. 90-100%
Answer» C. 70-80%
2.

The measurement of fractioned power by Willans line is applicable to

A. ci engine at particular speed
B. si engine at particular speed
C. any engine at particular speed
D. none of the above
Answer» B. si engine at particular speed
3.

Morse test is only applicable to

A. single cylinder si engine
B. single cylinder ci engine
C. multicylinder ci engine
D. single and multi cylinder si & ci engine
Answer» C. multicylinder ci engine
4.

The most accurate method of determining friction power is by

A. willans line
B. morse test
C. motoring test
D. measurement of brake and indicated power
Answer» D. measurement of brake and indicated power
5.

In the air base method of measuring air flow, the air base is provided to

A. damp out the pulsation
B. have a constant temperature
C. have a constant flow
D. provide constant velocity of flow
Answer» C. have a constant flow
6.

The air box/swept volume ratio should be in the range for single cylinder engine

A. 10-100%
B. 200-300%
C. 500-600%
D. 10
Answer» C. 500-600%
7.

The best method of measuring speed is by

A. mechanical tachometer
B. electrical tachometer
C. magnetic pick up
D. none of the above
Answer» A. mechanical tachometer
8.

flame ionization detector is used for measuring

A. hc
B. co
C. nox
D. co2
Answer» A. hc
9.

Chemilumme scene analyzer is used for measuring

A. hc
B. co
C. nox
D. co2
Answer» C. nox
10.

Non disprasive infrared analyzer is widely accepted instrument for measuring

A. unburnt hydrocarbon
B. carbon monoxide
C. carbon dioxide
D. nox
Answer» B. carbon monoxide
11.

If n is the rpm, number of power strokes per minute in a four stroke engine is

A. n/2
B. n
C. 2n
D. 4n
Answer» A. n/2
12.

If n is the rpm, number of power strokes per minute in a two stroke engine is

A. n/2
B. n
C. 2n
D. 4n
Answer» B. n
13.

mechanical efficiency 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 to frictional power
Answer» C. brake power to indicated power
14.

volumetric efficiency is a measure of

A. power of the engine
B. speed of the engine
C. breathing capacity of the engine
D. pressure rise in the cylinder
Answer» C. breathing capacity of the engine
15.

thermal efficiency varies

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
16.

The spark timing and combustion rate 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
17.

Indicated power is directly proportional to

A. air consumption
B. torque
C. cylinder peak pressure
D. none of the above
Answer» A. air consumption
18.

The brake thermal efficiency of SI engine is in the range of

A. 35-60%
B. 25-35
C. 60-80
D. none of the above
Answer» B. 25-35
19.

Performance m ep shows

A. indicated power vs speed
B. both vs soeed under various conditions
C. bmep vs piston speed under various condition
D. nth vs speed under various condition
Answer» C. bmep vs piston speed under various condition
20.

If performance of SI engine of different manufacturer having different capacities size and systems are to be compared, the common parameter would be

A. engine cylinder diameter
B. b.h.p.
C. speed
D. mep
Answer» D. mep
21.

Endurance test for IC engine is conducted for

A. 100hrs
B. 200 hrs
C. 400 hrs
D. 500 hrs
Answer» D. 500 hrs
22.

Which of the following factor will not assist in improving thermal efficiency of a CI engine

A. fine atomization and even distribution of fuel
B. minimum heat loss during combustion
C. clear exhaust
D. high surface to volume ratio
Answer» D. high surface to volume ratio
23.

which statement is correct

A. morse test can be conducted on petrol engine
B. morse test can be conducted on diesel engine
C. conducted only on multicylinder engines
D. none of the above
Answer» C. conducted only on multicylinder engines
24.

Rope brake dynamometer falls under the category of

A. hydraulic dynamometer
B. transmission type dynamometer
C. torsion type dynamometer
D. mechanical friction type dynamometer
Answer» D. mechanical friction type dynamometer
25.

Prony brakes are used for testing

A. small engine
B. large capacity engines
C. slow speed engines
D. high speed engines
Answer» A. small engine
26.

Which of the following is performed for super charging of IC engine?

A. roots blower
B. axial flow compressor
C. sliding vane type compressor
D. reciprocating compressor
Answer» B. axial flow compressor
27.

From the engine indicator diagram we obtain

A. imep
B. bmep
C. mechanical efficiency
D. relative efficiency
Answer» A. imep
28.

Most accurate dynamometer is

A. prony brake type
B. hydraulic type
C. swinginf field type
D. eddy current type
Answer» C. swinginf field type
29.

Most commonly used dynamometer on account of its simplicity of construction is the

A. brake type
B. hydraulic type
C. swinginf field type
D. eddy current type
Answer» A. brake type
30.

bmep in an engine depends up on its

A. speed only
B. torque only
C. speed and torque
D. speed and power
Answer» B. torque only
31.

Brake thermal efficiency of SI engine usually varies between

A. 25-30 %
B. 30-60 %
C. 60-80%
D. more than 80 %
Answer» A. 25-30 %
32.

The brake power is the

A. power available at the output shaft
B. energy developed inside the cylinder block
C. energy lost due to friction
D. none of the above
Answer» A. power available at the output shaft
33.

The total power developed by the combustion of fuel is

A. bp
B. ip
C. fp
D. none of the above
Answer» B. ip
34.

Mean effective pressure is the pressure

A. pressure acting on the crank shaft
B. which is acting on the piston throughout the power stroke
C. pressure required to inject the fuel
D. none of the above
Answer» B. which is acting on the piston throughout the power stroke
35.

Fuel Air ratio is

A. mass of fuel to mass of air
B. reciprocal of air fuel ratio
C. which effects the combustion phenomenon
D. all of the above
Answer» D. all of the above
36.

specific fuel consumption is

A. amount of fuel consumed per unit power developed per hour
B. amount of fuel consumed per unit indicated power 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
37.

Heat balance sheet indicates

A. amount of heat energy consumed in the combustion chamber
B. brake up of the total energy input into different parts
C. amount of energy lost through exhaust
D. all of the above
Answer» B. brake up of the total energy input into different parts
38.

The frictional power is

A. bp + ip
B. bp- ip
C. bp* ip
D. none of the above
Answer» B. bp- ip
39.

Identify the correct statement

A. power friction means less brake power
B. lower friction means more brake power
C. high friction means high brake power
D. lower friction means high brake specific fuel consumption
Answer» B. lower friction means more brake power
40.

Willians line method is applicable to

A. si
B. ci
C. both
D. none of the above
Answer» A. si
41.

The ratio of indicated thermal efficiency to the air std cycle efficiency is called

A. net efficiency
B. efficiency ratio
C. relative efficiency
D. overall efficiency
Answer» C. relative efficiency
42.

As compare to winter, during summer, volumetric efficiency of IC engine will

A. increase
B. decrease
C. same
D. unpredictable
Answer» B. decrease
43.

Pick up the wrong statement

A. supercharging reduces knocking in diesel engine
B. there can be limited supercharging in petrol engine because of detonation
C. supercharging at high altitudes is essential
D. supercharging results in to fuel economy
Answer» D. supercharging results in to fuel economy
44.

The ratio of BP to IP of an engine is

A. thermal effi
B. brake thermal effi
C. mechanical efficiency
D. overall efficiency
Answer» C. mechanical efficiency
45.

Volumetric efficiency of supercharged engine is

A. 1
B. cant determine
C. greater than 1
D. less than 1
Answer» C. greater than 1
46.

volumetric efficiency of naturally aspirated engine is

A. 1
B. cant determine
C. greater than 1
D. less than 1
Answer» D. less than 1
47.

The mean effective pressure indicates the

A. maximum pressure developed
B. minimum pressure developed
C. average pressure
D. instanteneous pressure at any instant
Answer» C. average pressure
48.

The ratio of BMEP to IMEP is called

A. mechanical efiiciency
B. overall efficiency
C. volumetric efficiency
D. indicated thermal effi
Answer» A. mechanical efiiciency
49.

The powern actually developed by the engine is called

A. theoretical power
B. actual power
C. ip
D. none of the above
Answer» C. ip
50.

The BP of diesel engine, keeping other parameters constant, can be increased by

A. decreasing the density of intake air
B. incrasing the temperature of intake air
C. increasing the pressure of intake air
D. decreasing the pressure of intake air
Answer» C. increasing the pressure of intake air
51.

Motoring test is carried out on an IC engine to determine

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