Courses
Courses for Kids
Free study material
Offline Centres
More
Store

# A thermodynamic process is shown in the figure. The pressure and volumes corresponding to some points in the figure are:${{\text{P}}_{\text{A}}}=3\times {{10}^{4}}\text{Pa}$$\mathrm{V}_{\mathrm{A}}=2 \times 10^{-3} \mathrm{m}^{-3}$${{\text{P}}_{\text{B}}}=8\times {{10}^{4}}\text{Pa}$$\mathrm{V}_{\mathrm{C}}=5 \times 10^{-3} \mathrm{m}^{-3}$In the process A B, 600 J of heat is added to the system and in process B C, 200 J of heat is added to the system. The change in internal energy of the system in process AC would be(A) 560 J(B) 800 J(C) 600 J(D) 640 J

Last updated date: 09th Apr 2024
Total views: 33.6k
Views today: 0.33k
Verified
33.6k+ views
Hint: We know that thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. In particular, it describes how thermal energy is converted to and from other forms of energy and how it affects matter. Traditionally, thermodynamics has stated three fundamental laws: the first law, the second law, and the third law. A more fundamental statement was later labelled the 'zeroth law'. The third law of thermodynamics states that a system's entropy approaches a constant value as the temperature approaches absolute zero. Entropy, the measure of a system's thermal energy per unit temperature that is unavailable for doing useful work. Because work is obtained from ordered molecular motion, the amount of entropy is also a measure of the molecular disorder, or randomness, of a system.

No work is done during the isochoric process $\mathrm{A} \rightarrow \mathrm{B}$.
Work done during isobaric process $\mathrm{B} \rightarrow \mathrm{C}=\mathrm{P}_{\mathrm{B}}\left(\mathrm{V}_{\mathrm{C}}-\mathrm{V}_{\mathrm{B}}\right)$
$=\mathrm{P}_{\mathrm{B}}\left(\mathrm{V}_{\mathrm{D}}-\mathrm{V}_{\mathrm{A}}\right)=240 \mathrm{J}$
From conservation of energy, $\mathrm{Q}=\mathrm{U}+\mathrm{W}$
$\Rightarrow \text{U}=\text{Q}-\text{W}=(600+200)\text{J}-240\text{J}=560\text{J}$