The heat absorbed or rejected by the working substance is given by (where ds = Increase or decrease of entropy, T = Absolute temperature, and dQ = Heat absorbed or rejected)
δQ = T.ds
δQ = T/ds
dQ = ds/T
None of these
Correct Answer :
A. δQ = T.ds
Related Questions
Strain is equal to (where l = Original length, and δl = Change in length)
l/δl
δl/l
l.δl
l + δl
The pressure exerted by an ideal gas is ________ of the kinetic energy of all the molecules contained in a unit volume of gas.
One-half
One-third
Two-third
Three-fourth
Select the wrong statement
A Joule cycle consists of two constant volume and two isentropic processes.
An Otto cycle consists of two constant volume and two isentropic processes.
An Ericsson cycle consists of two constant pressure and two isothermal processes.
All of the above
The intensity of stress which causes unit strain is called
Unit mass
Modulus of rigidity
Bulk modulus
Modulus of Elasticity
The thermodynamic difference between a Rankine cycle working with saturated steam and the Carnot cycle is that
Carnot cycle can't work with saturated steam
Heat is supplied to water at temperature below the maximum temperature of the cycle
A Rankine cycle receives heat at two places
Rankine cycle is hypothetical
The buckling load for a given column depends upon
Area of cross-section of the column
Length and least radius of gyration of the column
Modulus of elasticity for the material of the column
All of the above
The stress at which extension of the material takes place more quickly as compared to the increase in load is called
Elastic point of the material
Plastic point of the material
Breaking point of the material
Yielding point of the material
In order to know whether a column is long or short, we must know its
Ultimate shear stress of the column
Factor of safety
Torque resisting capacity
Slenderness ratio
The value of 1 mm of Hg is equal to
1.333 N/m2
13.33 N/m2
133.3 N/m2
1333 N/m2
Stirling and Ericsson cycles are
Reversible cycles
Irreversible cycles
Semi-reversible cycles
Quasi-static cycles
Which is the incorrect statement about Carnot cycle?
It is used as the alternate standard of comparison of all heat engines.
All the heat engines are based on Carnot cycle.
It provides concept of maximising work output between the two temperature limits.
All of the above
A beam is loaded as cantilever. If the load at the end is increased, the failure will occur
In the middle
At the tip below the load
At the support
Anywhere
Shear stress induced in a shaft subjected to tension will be
Maximum at periphery and zero at center
Maximum at center
Uniform throughout
None of the above
Mond gas is obtained by
Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
Carbonisation of bituminous coal
Passing steam over incandescent coke
Passing air and a large amount of steam over waste coal at about 650°C
A column that fails due to direct stress, is called
Short column
Long column
Weak column
Medium column
In S. I. units, the value of the universal gas constant is
8.314 J/kg mole-K
83.14 J/kgmole-K
831.4 J/kgmole-K
8314 J/kgmole-K
Which of the following statement is incorrect?
The liquid fuels consist of hydrocarbons.
The liquid fuels have higher calorific value than solid fuels.
The solid fuels have higher calorific value than liquid fuels.
A good fuel should have low ignition point.
When the gas is cooled at constant pressure,
Its temperature increases but volume decreases
Its volume increases but temperature decreases
Both temperature and volume increases
Both temperature and volume decreases
One kg of carbon monoxide requires __________ kg of oxygen to produce 11/7 kg of carbon dioxide gas.
4/7
11/4
9/7
All of these
The calorific value of gaseous fuel is expressed in
kJ
kJ/kg
kJ/m2
kJ/m3
Efficiency of a riveted joint is the ratio of its strength (max. load it can resist without failure) to the strength of the un-punched plate in
Tension
Compression
Bearing
Any one of the above
The temperature at which the volume of a gas becomes zero is called
Absolute scale of temperature
Absolute zero temperature
Absolute temperature
None of these
The efficiency and work ratio of a simple gas turbine cycle are
Very low
Low
High
Very high
Which of the following statement is correct?
The increase in entropy is obtained from a given quantity of heat at a low temperature.
The change in entropy may be regarded as a measure of the rate of the availability or unavailability of heat for transformation into work.
The entropy represents the maximum amount of work obtainable per degree drop in temperature.
All of the above
The ideal efficiency of a Brayton cycle with regeneration, with increase in pressure ratio will
Increase
Decrease
Remain unchanged
Increase/decrease depending on application
According to Kelvin-Planck's statement of second law of thermodynamics,
It is impossible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
It is possible to construct an engine working on a cyclic process, whose sole purpose is to convert heat energy into work
It is impossible to construct a device which operates in a cyclic process and produces no effect other than the transfer of heat from a cold body to a hot body
None of the above
One molecule of oxygen consists of __________ atoms of oxygen.
2
4
8
16
Strain is defined as the ratio of
Change in volume to original volume
Change in length to original length
Change in cross-sectional area to original cross-sectional area
Any one of the above
A process of heating crude oil to a high temperature under a very high pressure to increase the yield of lighter distillates, is known as
Cracking
Carbonisation
Fractional distillation
Full distillation
When a thin cylindrical shell is subjected to an internal pressure, the volumetric strain is (where ε₁ = Hoop strain, and ε₂ = Longitudinal strain)
2ε₁ - ε₂
2ε₁ + ε₂
2ε₂ - ε₁
2ε₂ + ε₁