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Mechanical Engineering MCQs with Explanations

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361Mechanical EngineeringMedium

Work study is done with the help of________?

Anone of the above

Bmaterial handling

Cprocess chart

Dstop watch

Eall of the above

Correct answer

D. stop watch

Explanation

The correct answer is stop watch.

362Mechanical EngineeringMedium

In boiling water reactor, moderator is________?

Ablanket of thorium

Bgraphite rod

Ccoolant itself

Dferrite rod

Eliquid sodium metal

Correct answer

C. coolant itself

Explanation

The correct answer is coolant itself.

363Mechanical EngineeringMedium

If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be________?

Amore/less depending on rating

Bunpredictable

Csame

Dless

Emore

Correct answer

E. more

Explanation

The correct answer is more.

364Mechanical EngineeringMedium

Which of the following is false statement in respect of differences between machine and structure________?

AMachines modify movement and work, whereas structures modify forces

BEfficiency of machines as well as structures is below 100%

CMachines transmit mechanical work, whereas structures transmit forces

DMachines are run by electric motors, but structures are not

EIn machines, relative motion exists be-tween its members, whereas same does hot exist in case of structures

Correct answer

B. Efficiency of machines as well as structures is below 100%

Explanation

The correct answer is Efficiency of machines as well as structures is below 100%.

365Mechanical EngineeringMedium

A cycle consisting of two adiabatics and two constant pressure processes is known as________?

AJoule cycle

BOtto cycle

CEricsson cycle

DStirling cycle

EAtkinson cycle

Correct answer

A. Joule cycle

Explanation

The correct answer is Joule cycle.

366Mechanical EngineeringMedium

The radius of a dished head is taken approximately as________?

Atwo

Bone

Cthree

Done-fourth

Ehalf

Correct answer

B. one

Explanation

The correct answer is one.

367Mechanical EngineeringMedium

According to Clausis statement of second law of thermodynamics________?

Aheat can be transferred from low temperature to high temperature source if COP of process is more than unity

Bheat can’t be transferred from low temperature to high temperature source without the aid of external energy

Call of the above

Dheat can’t be transferred from low temperature source to high temperature source

Eheat can be transferred for low temperature to high temperature source by using refrigeration cycle.

Correct answer

B. heat can’t be transferred from low temperature to high temperature source without the aid of external energy

Explanation

The correct answer is heat can’t be transferred from low temperature to high temperature source without the aid of external energy.

368Mechanical EngineeringMedium

In heat exchangers, degree of approach is defined as the difference between temperatures of________?

Ahot medium outlet and cold water inlet

Bhot medium inlet and outlet

Cnone of the above

Dcold water inlet and outlet

Ehot medium outlet and cold water outlet

Correct answer

E. hot medium outlet and cold water outlet

Explanation

The correct answer is hot medium outlet and cold water outlet.

369Mechanical EngineeringMedium

Water tube boilers are those in which________?

Awork is done during adiabatic expansion

Bflue gases pass through tubes and water around it

Cnone of the above

Dchange in enthalpy

Ewater passes through the tubes and flue gases around it

Correct answer

A. work is done during adiabatic expansion

Explanation

The correct answer is work is done during adiabatic expansion.

370Mechanical EngineeringMedium

In petrol engines, the maximum power is developed corresponding to relative fuel air ratio of________?

B1.1 to 1.3

C1.2 to 1.5

D0.85

Correct answer

B. 1.1 to 1.3

Explanation

The correct answer is 1.1 to 1.3.

Which of the following is false statement in respect of differences between machine and structure________?

AMachines modify movement and work, whereas structures modify forces

BEfficiency of machines as well as structures is below 100%

CMachines transmit mechanical work, whereas structures transmit forces

DMachines are run by electric motors, but structures are not

EIn machines, relative motion exists be-tween its members, whereas same does hot exist in case of structures

Correct answer

B. Efficiency of machines as well as structures is below 100%

Explanation

The correct answer is Efficiency of machines as well as structures is below 100%.

According to Clausis statement of second law of thermodynamics________?

Aheat can be transferred from low temperature to high temperature source if COP of process is more than unity

Bheat can’t be transferred from low temperature to high temperature source without the aid of external energy

Call of the above

Dheat can’t be transferred from low temperature source to high temperature source

Eheat can be transferred for low temperature to high temperature source by using refrigeration cycle.

Correct answer

B. heat can’t be transferred from low temperature to high temperature source without the aid of external energy

Explanation

The correct answer is heat can’t be transferred from low temperature to high temperature source without the aid of external energy.

Water tube boilers are those in which________?

Awork is done during adiabatic expansion

Bflue gases pass through tubes and water around it

Cnone of the above

Dchange in enthalpy

Ewater passes through the tubes and flue gases around it

Correct answer

A. work is done during adiabatic expansion

Explanation

The correct answer is work is done during adiabatic expansion.