Clement Desmorme's experiment for Adiabatic Index gamma

[hkinks]

Homework Statement

Basically the experiment itself can be found in here:
http://www.ce.tuiasi.ro/romana/publicatii/cursuri/radinschi_fizica/Lab2%20engleza.pdf
or here:
http://blog.cencophysics.com/2010/02/clement-desormes-experiment/

The experiment and all the necessary calculations are successfully done, but I also need to answer a question which I cannot figure out.

Why isn't adiabatic process enough in this experiment?

Homework Equations

$$p_1V_1^\gamma = p_2V_2^\gamma$$
$$\gamma=\frac{c_p}{c_v}$$

The Attempt at a Solution

The question itself is a bit confusing to me, but the way I understand it there has to be heat transfer so that initial temperature and final temperature could be the same after the change of pressure and we could use Boyle-Mariotte's law to find the gamma.
But that doesn't seem to be the real reason behind it.

Any ideas or clues could be really helpful.
Thank you

 

[mark726]

for your post and for providing the links to the experiment. From what I can gather, the experiment involves compressing air in a cylinder and measuring its temperature and pressure at different stages. The goal is to determine the value of gamma, the ratio of specific heats, for air.

To answer your question, let's first review the concept of an adiabatic process. An adiabatic process is one in which no heat is transferred between the system and its surroundings. In this experiment, the air in the cylinder is compressed quickly enough that there is not enough time for heat to be transferred between the air and the cylinder walls. Therefore, the process can be considered adiabatic.

Now, why isn't this enough for the experiment? Well, while an adiabatic process can help us determine the value of gamma, it is not sufficient on its own. This is because we need to know the pressure and volume at two different points in the process in order to use the adiabatic equation p_1V_1^\gamma = p_2V_2^\gamma. In this experiment, the pressure and volume are not constant throughout the process. The volume of air changes as it is compressed, and the pressure also changes due to the work done by the piston.

To fully understand the behavior of the air in the cylinder, we need to take into account all the factors that affect it, including the change in volume and the work done by the piston. This is why the experiment also involves measuring the temperature and pressure at different stages and using Boyle-Mariotte's law to find the value of gamma. This allows us to account for all the variables and accurately determine the value of gamma for air.

In summary, while an adiabatic process is important in this experiment, it is not enough on its own. We need to consider all the factors that affect the air in the cylinder in order to accurately determine the value of gamma. I hope this helps clarify the question for you. Let me know if you have any further questions.