How Do You Calculate Work Done in a Thermodynamic Process?

In summary, the conversation discusses a problem involving a fluid expanding in a cylinder with a piston. The pressure and specific volume of the fluid are given, and the goal is to calculate the work done during the process. The equation for work is provided, but it is noted that it only applies if the pressure is constant. Integration is suggested as a method for finding the work done in this case. The conversation concludes with a question about using a specific formula for the problem.
  • #1
Iain123
5
0

Homework Statement



Unit mass of a fluid at a pressure of 3 bar, and with a specific volume of 0.18 m^3/kg, contained in a cylinder fitted with a piston expands reversibly to a pressure of 0.6 bar according to the law p = c/v^2
, where c is a constant. Calculate the work done during the process. (Answer = 29.82 kJ)
[/B]

Homework Equations

The Attempt at a Solution



Hi guys, its been a few years since i did any thermodynamics and I am struggling to remember how to solve this problem, iv been unsuccessfully trying to use the specific volume to get V2, and then W= P*(V2-V1).
Any help greatly appreciated ![/B]
 
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  • #2
Your equation for work is valid only if the pressure is constant during the process. In the process you specify, the pressure is not a constant. In such a case, the work done is obtained by integration. Are you familiar with integration?
 
  • #3
Ah i see, so i use this formula ?
upload_2018-1-30_19-45-44.png

upload_2018-1-30_19-48-10.png

Trying this using V1 = 0.18 and V2 = 0.9, I'm getting an answer of around 87kJ :frown:
 

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  • #4
In your original statement, you said the process was

p = c / v2

But in your integral, you put p = c /v.
 

Related to How Do You Calculate Work Done in a Thermodynamic Process?

1. What is thermodynamics?

Thermodynamics is the branch of physics that deals with the relationship between heat and other forms of energy, such as work. It studies how energy is transferred and transformed in physical systems, and how these processes affect the properties of matter.

2. What are the laws of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed. The second law states that the total entropy of a closed system always increases over time. The third law states that the entropy of a perfect crystal at absolute zero temperature is zero.

3. How is thermodynamics applied in everyday life?

Thermodynamics has many applications in everyday life, such as in heating and cooling systems, engines, refrigerators, and cooking. It is also used in the study of weather and climate, as well as in chemical reactions and biological processes in the body.

4. What is the difference between heat and temperature?

Heat is a form of energy that is transferred from one object to another 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. Heat and temperature are related, but they are not the same thing.

5. How can I improve my understanding of basic thermodynamics?

To improve your understanding of basic thermodynamics, it is important to have a strong foundation in physics and mathematics. It is also helpful to practice solving problems and to seek out additional resources, such as textbooks, online tutorials, and study groups. Seek guidance from a knowledgeable teacher or mentor if needed.

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