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Mechanical Engineering MCQs with Explanations

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491Mechanical EngineeringMedium

A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t2 (t – 4), the acceleration of the particle will be given by the equation ________?

A3t2+2t

B6f-8

C6f-4

D3t2-lt

E6t2-8t

Correct answer

B. 6f-8

Explanation

The correct answer is 6f-8.

492Mechanical EngineeringMedium

If a refractory contains high content of silicon, it means refractory is________?

Anone of the above

Bneutral

Cacidic

Dbrittle

Ebasic

Correct answer

B. neutral

Explanation

The correct answer is neutral.

493Mechanical EngineeringMedium

Gas turbines for power generaion are normally used________?

Awhen other sources of power fail

Bto supply base load requirements

Cto supply peak load requirements

Dto enable start thermal power plant

Ein emergency

Correct answer

C. to supply peak load requirements

Explanation

The correct answer is to supply peak load requirements.

494Mechanical EngineeringMedium

The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will________?

Afirst increase, reach maximum and then decrease

Bdecrease continuously

Cnone of the above

Dincrease first at fast rate and then slow

Eincrease first at slow rate and then fast

Correct answer

A. first increase, reach maximum and then decrease

Explanation

The correct answer is first increase, reach maximum and then decrease.

495Mechanical EngineeringMedium

In ordetjo obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will ________?

Aimprove C. worsen

Bunpredictable

Cmay improve/worsen depending on size

Dremain unaffected

Correct answer

C. may improve/worsen depending on size

Explanation

The correct answer is may improve/worsen depending on size.

496Mechanical EngineeringMedium

The index of compression n tends to reach ratio of specific heats y when________?

Aprocess is isentropic and specific heat does not change with temperature

Bflow is uniform and steady

Cprocess is isentropic and specific heat changes with temperature

Dprocess is isentropic

Eprocess is isothermal

Correct answer

A. process is isentropic and specific heat does not change with temperature

Explanation

The correct answer is process is isentropic and specific heat does not change with temperature.

497Mechanical EngineeringMedium

The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed________?

A180°C

B320°C

C80°C

D240°C

E120°C

Correct answer

A. 180°C

Explanation

The correct answer is 180°C.

498Mechanical EngineeringMedium

Which of the following gases has the highest calorific value ________?

Awater gas

Bproducer gas

Cblast furnace gas

Dcoal gas

Ecoke oven gas

Correct answer

D. coal gas

Explanation

The correct answer is coal gas.

499Mechanical EngineeringMedium

Corrosion resistance of steel is increased by adding________?

Achromium and nickel

Baluminium and zinc

Cnickel and molybdenum

Dtungsten and sulfur

Enone of the above

Correct answer

A. chromium and nickel

Explanation

The correct answer is chromium and nickel.

500Mechanical EngineeringMedium

In multistage compressor, the isothermal compression is achieved by________?

Aby running compressor at very slow speed

Bby constantly cooling the cylinder

Cnone of the above

Dby insulating the cylinder

Eemploying intercooler

Correct answer

A. by running compressor at very slow speed

Explanation

The correct answer is by running compressor at very slow speed.

The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will________?

Afirst increase, reach maximum and then decrease

Bdecrease continuously

Cnone of the above

Dincrease first at fast rate and then slow

Eincrease first at slow rate and then fast

Correct answer

A. first increase, reach maximum and then decrease

Explanation

The correct answer is first increase, reach maximum and then decrease.

The index of compression n tends to reach ratio of specific heats y when________?

Aprocess is isentropic and specific heat does not change with temperature

Bflow is uniform and steady

Cprocess is isentropic and specific heat changes with temperature

Dprocess is isentropic

Eprocess is isothermal

Correct answer

A. process is isentropic and specific heat does not change with temperature

Explanation

The correct answer is process is isentropic and specific heat does not change with temperature.