MCQs

Mechanical Engineering MCQs with Explanations

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1741Mechanical EngineeringMedium

Fuel consumption of diesef engines is not guaranteed at one quarter load because at such low loads________?

Athe small difference in cooling water temperature or in internal friction has a disproportionate effect

Bthe friction is unpredictable

Cnone of the above

Dthe engine is rarely operated

Ethe friction is high

Correct answer

A. the small difference in cooling water temperature or in internal friction has a disproportionate effect

Explanation

The correct answer is the small difference in cooling water temperature or in internal friction has a disproportionate effect.

1742Mechanical EngineeringMedium

According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies________?

Anone of the above

Bdirectly as fan speed

Ccube of fan speed

Dsquare root of fan speed

Esquare of fan speed

Correct answer

B. directly as fan speed

Explanation

The correct answer is directly as fan speed.

1743Mechanical EngineeringMedium

During throttling process________?

Ano work is done by expanding steam

Bheat exchange does not take place

Call of the above

Dentropy decreases

Ethere is no change of internal energy of steam

Correct answer

C. all of the above

Explanation

The correct answer is all of the above.

1744Mechanical EngineeringMedium

Paramagnetic alpha iron changes to gamma iron at________?

A770°C

B1440°C

C910°C

D1539°C

Enone of the above

Correct answer

C. 910°C

Explanation

The correct answer is 910°C.

1745Mechanical EngineeringMedium

Perminvar alloy having constant permeability is an alloy of________?

Airon, zinc and bismuth

Bcopper, nickel and antimony

Cnickel, copper and iron

Dnickel, copper and zinc

Eantimony, copper and zinc

Correct answer

C. nickel, copper and iron

Explanation

The correct answer is nickel, copper and iron.

1746Mechanical EngineeringMedium

Vertical lines on pressure-enthalpy chart show constant________?

Apressure lines

Btotal heat lines

Cvolume lines

Dentropy lines

Etemperature lines

Correct answer

B. total heat lines

Explanation

The correct answer is total heat lines.

1747Mechanical EngineeringMedium

Which of the following is secondary fuel?

ATh232andU238

Bnon oh these

CU233andPu239

DU233andPu238

Correct answer

D. U233andPu238

Explanation

The correct answer is U233andPu238.

1748Mechanical EngineeringMedium

Work ratio of a gas turbine plant is ratio of________?

Awork done by turbine and net work output

Bactual/heat drop and isentropic heat drop

Cnet work output and heat supplied

Dwork done by turbine and heat supplied

Enet work output and work done by turbine

Correct answer

E. net work output and work done by turbine

Explanation

The correct answer is net work output and work done by turbine.

1749Mechanical EngineeringMedium

Joule sec is the unit of________?

Anone of the above

Buniversal gas constant

Ckinematic viscosity

Dthermal conductivity

EPlanck’s constant

Correct answer

E. Planck’s constant

Explanation

The correct answer is Planck’s constant.

1750Mechanical EngineeringMedium

Hardness of lower bainite (tempered martensite) is about________?

ARC 32

BRC 65

CRC 80

DRC 57

ERC 48

Correct answer

D. RC 57

Explanation

The correct answer is RC 57.

Fuel consumption of diesef engines is not guaranteed at one quarter load because at such low loads________?

Athe small difference in cooling water temperature or in internal friction has a disproportionate effect

Bthe friction is unpredictable

Cnone of the above

Dthe engine is rarely operated

Ethe friction is high

Correct answer

A. the small difference in cooling water temperature or in internal friction has a disproportionate effect

Explanation

The correct answer is the small difference in cooling water temperature or in internal friction has a disproportionate effect.

Work ratio of a gas turbine plant is ratio of________?

Awork done by turbine and net work output

Bactual/heat drop and isentropic heat drop

Cnet work output and heat supplied

Dwork done by turbine and heat supplied

Enet work output and work done by turbine

Correct answer

E. net work output and work done by turbine

Explanation

The correct answer is net work output and work done by turbine.