Thermodynamics-Pressure problem

[jakeward46]

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.

 

[edgepflow]

Think of the definition of "isobaric." Also, can you determine an equation for the work done by the piston?

 

[jakeward46]

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,

 

[edgepflow]

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?

 

[jakeward46]

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

 

[edgepflow]

That is good.

Now since the process is isobaric (constant pressure),

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

 

[jakeward46]

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

 

[edgepflow]

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.

 

[jakeward46]

Ok will have a go, not to sure though, thanks

 

[jakeward46]

V2=9.9846 litres!

 

[jakeward46]

Scrap that,V2=25.4 litres