mechanical engineering MCQs – Page 58

Practise multiple-choice questions from mechanical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

2851. In the lever of third order, load W, effort P and fulcrum F are oriented as follows_________________?
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A. P between W and F

B. W between P and F

C. F between W and P

D. W, P and F all on one side

E. none of the above

2852. The ultimate tensile stress of mild steel compared to ultimate compressive stress is__________________?
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A. less

B. same

C. unpredictable

D. more or less depending on other factors

E. more
2853. Modulus of rigidity is defined as the ratio of_________________?
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A. volumetric stress and volumetric strain

B. longitudinal stress and longitudinal strain

C. shear stress and shear strain

D. lateral stress and lateral strain

E. linear stress and lateral strain

2854. The stress developed in a material at breaking point in extension is called__________?
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A. Breaking stress

B. Proof stress

C. Fracture stress

D. Yield point stress

2855. A thin mild steel wire is loaded by adding loads in equal increments till it breaks. The extensions noted with increasing loads will behave as under_________________?
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A. first increase and then decrease

B. uniform throughout

C. increase uniformly first and then increase rapidly

D. increase rapidly first and then uniformly

E. increase uniformly

2856. The unit of Youngs modulus is__________________?
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A. kg/cm

B. kg

C. kg cm2

D. kg/cm2

E. mm/mm

2857. Solids and liquids have___________________?
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A. one value under some conditions and two values under other conditions

B. one value of specific heat (ft) two values of specific heat

C. three values of specific heat

D. no value of specific heat

2858. Change in internal energy in a closed system is equal to heat transferred if the reversible process takes place at constant_______________?
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A. temperature

B. volume

C. internal energy

D. entropy

E. pressure

2859. Brayton cycle consists of following four processes____________________?
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A. two isentropics and two constant volumes

B. two isentropics and two constant pres-sures

C. two isentropics, one constant volume and one constant pressure

D. none of the above

E. two isothermals and two isentropics

2860. Which of the following cycles is not a reversible cycle_____________________?
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A. Stirling

B. none of the above

C. Joule

D. Carnot

E. Ericsson

2861. Intensive property of a system is one whose value____________________?
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A. depends on the mass of the system, like volume

B. does not depend on the mass of the system, like temperature, pressure, etc

C. remains constant

D. is dependent on the path followed and not on the state

E. is not dependent on the path followed but on the state

2862. The efficiency of Diesei cycle with decrease in cut off_________________?
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A. remains unaffected

B. first decreases and then increases

C. first increases and then decreases

D. increases

E. decreases

2863. If both Stirling and Carnot cycles operate within the same temperature limits, then efficiency of Stirling cycle as compared to Carnot cycle___________________?
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A. none of the above

B. more

C. equal

D. less

E. depends on other factors

2864. According to Clausis statement of second law of thermodynamics___________________?
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A. all of the above

B. heat cant be transferred from low temperature source to high temperature source

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

D. heat cant be transferred from low temperature to high temperature source without the aid of external energy

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

2865. The ideal efficiency of a Brayton cycle without regeneration with increase ni pressure ratio will_________________?
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A. decrease

B. increase

C. remain unchanged

D. increase/decrease depending on application

E. unpredictable

2866. For a thermodynamic process to be reversible, the temperature difference between hot body and working substance should be___________________?
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A. minimum

B. maximum

C. zero

D. infinity

E. there is no such criterion

2867. Water contained in a beaker can be made to boil by passing steam through it__________________?
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A. any pressure

B. at atmospheric pressure

C. not possible

D. at a pressure greater than atmospheric pressure

E. at a pressure below the firuosphejric pressure

2868. Barometric pressure is equal to_____________________?
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A. 1 mm Hg

B. 760 mm Hg

C. 735.6 mm Hg

D. zero mm Hg

E. 100mm Hg

2869. In a free expansion process___________________?
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A. work done is zero

B. heat transfer is zero

C. both A. and B. above

D. work done is zero but heat increases

E. work done is zero but heat decreases

2870. The cycle in which heat is supplied at constant volume and rejected at constant pressure is known as_________________?
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A. Diesel cycle

B. Rankine cycle

C. Atkinson cycle

D. Stirling cycle

E. Dual combustion cycle

2871. First law of thermodynamics___________________?
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A. provides relationship between heat, work and internal energy

B. enables to determine change in internal energy of the system

C. does not help to predict whether the system will or not undergo a change

D. all of the above

E. does not enable to determine change in entropy

2872. Energy can neither be created nor destroyed but can be converted from one form to other is inferred from_________________?
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A. basic law of thermodynamics

B. second law to thermodynamics

C. claussius statement

D. zeroth low of thermodynamic

E. first law of thermodynamics
2873. Which law states that the specific heat of a gas remains constant at all temperatures and pressures______________________?
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A. there is no such law

B. Joules Law

C. Regnaults Law

D. Boyles Law

E. Charles Law

2874. A perpetual motion machine is___________________?
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A. a non-thermodynamic machine

B. a hypothetical machine whose opera-tion would violate the laws of thermodynamics

C. a thermodynamic machine

D. an inefficient machine

E. a hypothetical machine

2875. Which of the following laws is applicable for the behavior of a perfect gas__________________?
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A. Joules law

B. Gay-Lussac law

C. all of the above

D. Charleslaw

E. Boyles law

2876. In order that a cycle be reversible, following must be satisfied ________________?
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A. when heat is being absorbed, temperature of hot source and working substance should be same

B. when beat is being rejected, temperature of cold source and working sub-stance should be same

C. none of the above

D. free expansion or friction resisted expansion/compression process should not be encountered

E. all of the above
2877. Specific heat of air at constant pressure is equal to___________________?
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A. 1.41

B. 0.21

C. 0.17

D. 0.24

E. 1

2878. One barometric pressure or 1 atmospheric pressure is equal to___________________?
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A. 1.0197 kgf/cm2

B. 1.033 kgf/cm2

C. 0 kgf/cm2

D. 1 kgf/cnr2

E. 100 kgf/cm2

2879. For same compression ratio and for same heat added_________________?
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A. Otto cycle is more efficient than Diesel cycle

B. Diesel cycle is more efficient than Otto cycle

C. efficiency depends on other factors

D. both Otto and Diesel cycles are equally efficient

E. none of the above

2880. Which of the following processes are thermodynamically reversible___________________?
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A. hyperbolic and pV = C

B. constant volume and constant pressure

C. throttling

D. free expansion

E. isothermal and adiabatic
2881. According to Gay-Lussac law for a perfect gas, the absolute pressure of given mass varies directly as____________________?
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A. remains constant,if volume and temperature are kept constant

B. absolute temperature, if volume is kept constant

C. volume, if temperature is kept constant

D. temperature

E. absolute

2882. According to first law of thermodynamics_______________________?
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A. mass and energy are mutually convertible

B. heat and work are mutually convertible

C. Carnot engine is most efficient

D. mass and light are mutually convertible

E. heat flows from hot substance to cold substance

2883. Otto cycle consists of following four processes____________________?
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A. two isentropics and two constant pres-sures

B. two isothermals and two isentropics

C. two isentropics and two constant volumes

D. none of the above

E. two isentropics, one constant volume and one constant pressure

2884. Carnot cycle is__________________?
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A. an adiabatic irreversible cycle

B. a quasi static cycle

C. a semi-reversible cycle

D. a reversible cycle (ft) an irreversible cycle
2885. According to which law, all perfect gases change in volume by l/273th of their original volume at 0C for every 1C change in temperature when pressure remains constant ____________________?
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A. Gay-Lussac law

B. Boyles law

C. Regnaults law

D. Joules law

E. Charles law
2886. According to Avogadros Hypothesis ______________________?
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A. the sum of partial pressure of mixture of two gases is sum of the two

B. all systems can be regarded as closed systems

C. gases have two values of specific heat

D. product of the gas constant and the molecular weight of an ideal gas is constant

E. the molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature
2887. During throttling process___________________?
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A. there is no change of internal energy of steam

B. entropy decreases

C. no work is done by expanding steam

D. heat exchange does not take place

E. all of the above
2888. Which of the following items is not a path function ____________________?
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A. vdp

B. kinetic energy

C. heat

D. work

E. thermal conductivity
2889. Carnot cycle has maximum efficiency for__________________?
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A. reversible engine

B. irreversible engine

C. petrol engine

D. new engine

E. diesel engine

2890. The unit of energy in S.I. units is________________?
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A. joule/s

B. joule

C. joule/m

D. joule m.

E. watt

2891. I kgf/cm2 is equal to________________?
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A. 1 mm Hg

B. lOOmmHg

C. 735.6 mm Hg

D. 760 mm Hg

E. zero mm Hg

2892. An actual engine is to be designed having same efficiency as the Carnot cycle. Such a proposition is___________________?
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A. desirable

B. possible

C. possible, but with lot of sophistications

D. impossible

E. feasible

2893. The unit of power in S.I. units is_______________________?
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A. watt

B. erg

C. newton

D. pascal

E. joule

2894. The ideal efficiency of a Brayton cycle with regeneration, with increase in pressure ratio will______________?
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A. remain unchanged

B. decrease

C. increase/decrease depending on ap-plication

D. unpredictable

E. increase

2895. The unit of temperature in S.I. units is _________________?
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A. Kelvin

B. Fahrenheit

C. Centigrade

D. Celsius

E. Rankine

2896. Gas turbine cycle consists of___________________?
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A. none of the above

B. two isentropics and two constant pressures

C. two isentropics, one constant volume and one constant pressure

D. two isentropics and two constant volumes

E. two isothermals and two isentropics

2897. Kinetic theory of gases assumes that the collisions between the molecules are________________?
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A. perfectly inelastic

B. perfectly elastic

C. partly inelastic

D. partly elastic and partly inelastic

E. partly elastic

2898. Zeroth law of thermodynamics________________?
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A. deals with conversion of mass and energy

B. deals with reversibility and irreversibility of process

C. states that if two systems are both in equilibrium with a third system, they are in thermal equilibrium with each other

D. deals with heat engines

E. does not exist

2899. Which of the following variables controls the physical properties of a perfect gas_________________?
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A. temperature

B. all of the above

C. pressure

D. volume

E. atomic mass

2900. Which of the following parameters is constant for a mole for most of the gases at a given temperature and pressure___________________?
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A. specific volume

B. entropy

C. mass

D. enthalpy

E. volume