PV diagrams monatomic ideal gas

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SUMMARY

The discussion focuses on calculating the work done on a monatomic ideal gas transitioning from state A to state D via a PV diagram, specifically through a constant pressure path A-E and a constant temperature path E-D. The user initially calculated the work done using the formula W = P_i(V_f - V_i) but questioned the correctness of their approach, particularly regarding the pressure values used for each segment of the process. The correct interpretation of pressure during isothermal processes and the application of the first law of thermodynamics are critical to accurately determining work, internal energy change, and heat flow.

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lalahelp
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Homework Statement


Suppose a monatomic ideal gas is changed from state A to state D by one of the processes shown on the PV diagram. (Let V1 = 4.80 L and P1 = 3.30 atm.)

(a) Find the total work done on the gas if it follows the constant pressure path A−E followed by the constant temperature path E−D.
(b)Calculate the total change in internal energy of the gas during the entire process.
(c)Calculate the total heat flow into the gas


2. W=pi(vf-vi)
(1.01e5)(3.3)(9.6-4.8)(.001)=1599.84 J
(1.01e5)(6.6+3.3)(19.2-9.6)(.001)= 4799.5 J
=6399 J

Why is my work wrong??
 

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lalahelp said:

Homework Statement


Suppose a monatomic ideal gas is changed from state A to state D by one of the processes shown on the PV diagram. (Let V1 = 4.80 L and P1 = 3.30 atm.)

(a) Find the total work done on the gas if it follows the constant pressure path A−E followed by the constant temperature path E−D.
(b)Calculate the total change in internal energy of the gas during the entire process.
(c)Calculate the total heat flow into the gas


2. W=pi(vf-vi)
(1.01e5)(3.3)(9.6-4.8)(.001)=1599.84 J
(1.01e5)(6.6+3.3)(19.2-9.6)(.001)= 4799.5 J
=6399 J

Why is my work wrong??
I am having trouble following your reasoning.

First, why would W = Pi(Vf-Vi) if the pressure is constant at 2Pi for A-E?

Second, why would you use 3Pi for the E-D path? Is the pressure constant during that process? What is the relationship between P and V during an isothermal process?

AM
 

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