Two Carnot engines A and B are operated in series. The first one, A, receives heat at T₁ (= 600 K) and rejects to a reservoir at temperature T₂. The second engine B receives heat rejected by the first engine and, in tum, rejects to a heat reservoir at T₃ (=400 K). Calculate the temperature T₂ if the work outputs of the two engines are equal :

A 15 g mass of nitrogen gas is enclosed in a vessel at a temperature 27^oC. Amount of heat transferred to the gas, so that rms velocity of molecules is doubled, is about : [Take R = 8.3 J/K mole]

Temperature difference of 120^oC is maintained between ends of a uniform rod AB of length 2L. Another bent rod PQ, of same cross-section as AB and length $${{3L} \over 2},$$ is connected across AB (see figure). In steady state, temperature difference between P and Q will be close to :

A gas can be taken from A to B via two different processes ACB and ADB.


When path ACB is used 60 J of heat flows into the system and 30 J of work is done by the system. If path ADB is used work done by the system is 10 J. The heat Flow into the system in path ADB is :