Engineering :: Thermodynamics

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361.

Five people must be lifted in an elevator to a distance of 100 m. The work is found to be 341.2 kJ and the gravitational acceleration is 9.75 m/s2. The average mass per person is

A.	65 kg	B.	72 kg
C.	70 kg	D.	67.5 kg

362.

An elastic sphere of 0.5 m diameter contains a gas at 115 k Pa. Heating of the sphere causes it to increase to 0.62 m and during the process the pressure is proportional to the sphere diameter. The work done by the gas will be

A.	7.7 kJ	B.	9.9 kJ
C.	11 kJ	D.	15 kJ

363.

The dew point temperature of humid air is

A.	always higher than the wet bulb temperature	B.	never lower than the wet bulb temperature
C.	the temperature of air obtained on cooling it till saturation at constant pressure	D.	the temperature of air obtained on cooling it till saturation at constant volume

364.

When two gases are not under the same conditions of temperature and pressure, upon mixing there will be

A.	loss of entropy to the surroundings	B.	exchange of entropy between the two gases
C.	increase in available heat but decrease in unavailable heat	D.	None of the above

365.

According to Amagat's law

A.	the sum of the volume friction is unity	B.	there would be no volume change if the components are mixed while holding the temperature and pressure constant
C.	all diatomic gases occupy double the volume of monoatomic gases for identical masses	D.	None of the above

366.

In which of the following energy conversion takes place at ambient temperature?

A.	Magnetohydrodynamic conversion	B.	Thermionic generator
C.	Battery producing electrical energy	D.	Solar radiation

367.

Entropy of mixing is always

A.	Zero	B.	positive
C.	Negative

368.

The mixing process of two fluids is always considered as

A.	reversible	B.	irreversible
C.	reversible or irreversible depending upon the gases involved

369.

For a closed system, the difference between the heat added to the system and the work done by the system is equal to the change in

A.	enthalpy	B.	entropy
C.	temperature	D.	internal energy

370.

Reduced pressure is

A.	always less than atmospheric pressure	B.	always unity
C.	an index of molecular position of gas	D.	dimensionless