We consider a thermodynamic system. If ΔU represents the increase in its internal energy and W the work done by the system, which of the following statements is true?
ΔU = - W in an adiabatic process
ΔU = W in an isothermal process
ΔU = - W in an isothermal process
ΔU = W in an adiabatic process
A Carnot engine whose sink is at 300 K has an efficiency of 40%. By how much should the temperature of the source be increased so as to increase its efficiency by 50% of original efficiency?
275 K
325 K
250 K
380 K
The temperature of source and sink of a heat engine is 127oC and 27oC respectively. An inventor claims its efficiency to be 26%, then:
It is impossible
It is possible with high probability
It is possible with low probability
Data are insufficient
An ideal gas is compressed adiabatically to 8/27 times of its present value at 27oC. The temperature of the gas becomes: (γ= 5/3).
475oC
275oC
402oC
175oC
In an adiabatic system which is true ?
PγTγ-1 = constant
PγT1-γ = constant
PTγ = constant
P1-γTγ = constant
In a given process of an ideal gas, dW = 0 and dQ < 0. Then for the gas:
The temperature will decrease
The volume will increase
The pressure will remain constant
The temperature will increase
A diatomic ideal gas is used in a Carnot engine as the working substance. If during the adiabatic expansion part of the cycle the volume of the has increased from V to 32 V, the efficiency of the engine is:
0.25
0.5
0.75
0.99
The efficiency of a Carnot engine operating between temperatures of 100oC and -23oC will be:
The efficiency of a Carnot engine is 50% and temperature of the sink is 500 K. If the temperature of source is kept constant and its efficiency is to be raised to 60%, then the required temperature of the sink will be:
600 K
500 K
400 K
100 K
When a system is taken from the initial state i to final state f along he path iaf, it is found that Q = 50 cal and W = 20 cal. If along the path ibf, Q = 36 cal, then W along the path ibf is:
6 cal
16 cal
66 cal
14 cal
