A thermodynamic system is taken through the cycle PQRSP process. The net work done by the system is :
20 J
-20 J
400 J
-374 J
An ideal monoatomic gas is taken round the cycle ABCDA as shown in the P-V diagram.
PV
2 PV
PV / 2
zero
Even Carnot engine cannot give 100% efficiency, because we cannot :
Prevent radiation
Find ideal sources
Reach absolute zero temperature
Eliminate friction
One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, the final temperature of gas will be:
(T + 2.4)K
(T - 2.4)K
(T + 4)K
(T - 4)K
An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62oC, its efficiency is doubled. The temperature of the source is:
124oC
37oC
62oC
99oC
Let 110 J of heat is added to a gaseous system, whose internal energy is 40 J, then the amount of external work done is:
150 J
70 J
110 J
40 J
An ideal gas initially at P1, V1 is expanded to P2, V2 and then compressed adiabatically to the same volume V1 and pressure P3. If W is the net work done by the gas in complete process, which of the following is true ?
W > 0 ; P3 > P1
W < 0 ; P3 > P1
W > 0 ; P3 < P1
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
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
The number of translational degree of freedom for a diatomic gas is:
2
3
5
6