help please.. In the figure shown, the volume at point C is 800 L and the pressure is 2 atm. The volume at a is 400 L and the pressure is 5 atm. (a) What is the wor

Question

In the figure shown, the volume at point C is 800 L and the pressure is 2 atm. The volume at a is 400 L and the pressure is 5 atm. (a) What is the work done as the system goes through one complete cycle abcda Is it work done by the system or work done on the system? (b) What is the heat transfer in one complete cycle abcda? Is the heat flowing into the system or flowing out of the systems?

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Answer 1

a). W_bc=0 and W_da=0 as dV=0 at those intervals.

W_ab=P_a(V_b-V_a)=(5 atm)(0.8 m³-0.4 m³)=2.02*10⁵ J

1 atm=1.01*10⁵ N/m² 1 J=(1 N)*(1 m)

 W_cd=( 2 atm)(0.4 m³ -0.8 m³)= - 0.808*10⁵ J

 Then W_abcd= (2.02-0.808)*10⁵ J =1.212*10⁵ J That is, work W_abcd  is positive and the work has done on the system.

b) To answer the question we need to make an assumption. Let’s consider the system as a closed one. Then by using the first Law of thermodynamics W_abcd=Q >0, that is,  the heat flows in the system.