Thermodynamics-Pressure problem

  • Thread starter jakeward46
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In summary, in this conversation, the problem of finding the final volume of a piston cylinder with given initial conditions (diameter, volume, pressure, and temperature) is discussed. The process is determined to be isobaric, and the equation for work is derived as W = P.dV. Using this equation and the given work value, the final volume is calculated to be 25.4 litres.
  • #1
jakeward46
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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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  • #2
Think of the definition of "isobaric." Also, can you determine an equation for the work done by the piston?
 
  • #3
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,
 
  • #4
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?
 
  • #5
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
 
  • #6
That is good.

Now since the process is isobaric (constant pressure),

what is the value of W = Integral (P dV)?
 
  • #7
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
 
  • #8
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:
  • #9
Ok will have a go, not to sure though, thanks
 
  • #10
V2=9.9846 litres!
 
  • #11
Scrap that,V2=25.4 litres
 

1. What is the relationship between pressure and temperature in thermodynamics?

In thermodynamics, pressure and temperature are directly proportional to each other. This means that as one increases, the other also increases. This relationship is described by the ideal gas law, which states that pressure is equal to the product of the gas's temperature and the number of moles of gas, divided by its volume.

2. How does pressure affect the behavior of gases in thermodynamics?

In thermodynamics, pressure affects the behavior of gases by determining how much they compress or expand. When pressure is increased, the volume of a gas decreases and its temperature increases. When pressure is decreased, the gas expands and its temperature decreases. This is known as the ideal gas law.

3. What are the units of pressure in thermodynamics?

The units of pressure in thermodynamics are typically expressed in pascals (Pa) or newtons per square meter (N/m2). Other common units include atmospheres (atm), millimeters of mercury (mmHg), and pounds per square inch (psi).

4. How is pressure related to work in thermodynamics?

In thermodynamics, pressure is related to work through the equation W = PΔV, where W is the work done, P is the pressure, and ΔV is the change in volume. This means that when pressure is applied to a gas, it can do work by expanding or compressing.

5. Can thermodynamics explain the behavior of liquids and solids under pressure?

Yes, thermodynamics can explain the behavior of liquids and solids under pressure. The principles of thermodynamics, such as the ideal gas law, can be applied to any type of matter, whether it is a gas, liquid, or solid. However, the behavior of liquids and solids under pressure may also be influenced by other factors, such as intermolecular forces.

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