Question 277: Thermodynamics & KTG

Question

A sample of an ideal gas is taken through the cyclic process ABCA as shown in figure. It absorbs, 40 J of heat during the part AB, no heat during BC and rejects 60 J of heat during CA. A work of 50 J is done on the gas during the part BC. The internal energy of the gas at A is 1560 J. The workdone by the gas during the part CA is :

Accepted Answer

$$\Delta$$U
AB
= 40 J as process is isochoric.
$$\Delta$$U
BC
= + 50 (W
BC
= $$-$$ 50 J)
U
C
= U
A
+ $$\Delta$$U
AB
+ $$\Delta$$U
BC
= 1650
For CA process,
Q
CA
= $$-$$ 60 J
$$\Delta$$U
CA
+ W
CA
= $$-$$60
$$-$$90 + W
CA
= $$-$$ 60
$$\Rightarrow$$ W
CA
= +30 J
The graph given is inconsistent with the statement BC may be adiabatic and CA cannot be like isobaric as shown, as increasing volume while rejecting heat at same time.

Answer

20 J

Answer

30 J

Answer

$$-$$30 J

Answer

$$-$$60 J

Thermodynamics & KTG

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