How do I solve for V in terms of p?

In summary, the conversation discusses a problem involving a gaseous substance undergoing an internally reversible process with a given equation for volume in terms of pressure. The integrals -/ V dp and /p dV are used to determine the change in volume and pressure, respectively, when the pressure changes from 1000psfa to 100psfa. The equations -/ V dp and /p dV are used for closed systems and steady flow, respectively, and can be solved by plugging in the given equation for volume in terms of pressure and using the initial and final pressure values.
  • #1
psan6
8
0
can somebody help me in solving this problem..thanks..

A gaseous substance whose properties are unknown, except as specified below, undergoes an internally reversible process during which

V = (-0.1p + 300)ft cube, when p is in psfa.

(a) for this process, find -/ V dp and /p dV, both in Btu, if the pressure changes from 1000psfa to 100psfa.

(/) means integral..thanks
 
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  • #2
psan6 said:
can somebody help me in solving this problem..thanks..

A gaseous substance whose properties are unknown, except as specified below, undergoes an internally reversible process during which

V = (-0.1p + 300)ft cube, when p is in psfa.

(a) for this process, find -/ V dp and /p dV, both in Btu, if the pressure changes from 1000psfa to 100psfa.

(/) means integral..thanks

This question doesn't make much sense but I suspect they're trying to impress upon you the importance of knowing what system your dealing with. Pdv is for closed systems. Vdp is for steady flow. You could try:
[tex]\int PdV = P_{avg}(V_2-V_1) [/tex]
and
[tex] \int -VdP = -V_{avg}(P_2-P_1)[/tex]
You can find V2 and V1 from your first equation.
 
  • #3
What specifically is the problem? You don't know how to set up the problem or you don't know how to do the integrals? You have volume as a function of pressure - plug that expression into the integrals and integrate - of course, you'll have to solve the expression for pressure in terms of volume for one of the integrals. You're also given the initial and final pressure, so you can use that to find the intial and final volume.

For the integral with respect to pressure,

[tex]\int_{p_0}^{p_f}dp~V = \int_{p_0}^{p_f}dp~(-0.1p + 300)[/tex]

Can you integrate that?

For the other integral, express pressure as a function of volume, and perform the integral [itex]\int dV~p[/itex].
 

Related to How do I solve for V in terms of p?

1. What is the first law of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, but can only be converted from one form to another. This means that the total amount of energy in a closed system remains constant.

2. What is the difference between heat and temperature?

Heat refers to the transfer of energy between objects due to a difference in temperature. Temperature, on the other hand, is a measure of the average kinetic energy of the particles in a substance.

3. How does the first law of thermodynamics apply to everyday life?

The first law of thermodynamics applies to many everyday processes, such as cooking, driving a car, and even breathing. It helps us understand how energy is transferred and conserved in these activities.

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5. How is the first law of thermodynamics related to the conservation of mass?

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