Thermodynamics-Pressure problem

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The discussion revolves around solving a thermodynamics problem involving a piston-cylinder system undergoing an isobaric process. The initial conditions include a diameter of 25 cm, an initial volume of 10 liters, a pressure of 650 kPa, and a temperature of 300 K, with the piston delivering 10 kJ of work. Participants discuss the relevant equations, particularly focusing on the work done by the piston, which is expressed as W = P dV for constant pressure. After some calculations and clarifications on the integration process, the final volume V2 is determined to be approximately 25.4 liters. This highlights the importance of understanding isobaric processes and the relationship between pressure, volume, and work in thermodynamic systems.
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Homework Statement



A piston cylinder with a diameter of 25cm and an initial volume V1 of 10litres, contains air at pressure P1 of 650kPa and a temp T1 of 300K, an Isobaric process pccurs and the piston delivers 10kJ of work.
Find the final volume V2 of the piston/cylinder in litres.

Homework Equations





The Attempt at a Solution



Ive tried using all different types of forumlas in different orders but i cannot come up with a reasonable answer, if someone could tell me the correct formulas to start the solution, that would be much appriciated.
 
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Think of the definition of "isobaric." Also, can you determine an equation for the work done by the piston?
 
edgepflow said:
Think of the definition of "isobaric." Also, can you determine an equation for the work done by the piston?

well , W= F.d but i probably cannot use that without first working out for other info. The isobaric, constant pressure,
 
OK, now let's go a step further.

Yes, dW = F dx or W = Integral (F dx)

Now consider the definition of Pressure: Pressure = Force / Area.

Can you update the work formula with pressure?
 
edgepflow said:
OK, now let's go a step further.

Yes, dW = F dx or W = Integral (F dx)

Now consider the definition of Pressure: Pressure = Force / Area.

Can you update the work formula with pressure?

Ok, dW = P.dV --> W=P.dV
 
That is good.

Now since the process is isobaric (constant pressure),

what is the value of W = Integral (P dV)?
 
edgepflow said:
That is good.

Now since the process is isobaric (constant pressure),

what is the value of W = Integral (P dV)?

how can i get the value of W when i do not have the difference in volume
 
jakeward46 said:
how can i get the value of W when i do not have the difference in volume
Recall the problem statement: they give you the work and ask you to find the final volume. So for constant P, what is the integral of P dV? Integrate from V1 to V2 for constant P.
 
Last edited:
Ok will have a go, not to sure though, thanks
 
  • #10
V2=9.9846 litres!
 
  • #11
Scrap that,V2=25.4 litres
 

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