Lec 2 | MIT 5.60 Thermodynamics & Kinetics, Spring 2008
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it as a reference for basic thermodynamics, especially how the Kelvin scale is defined and what makes a process reversible, and they cite specific timestamps when asking follow-up questions.
Recommended by 1 people across 1 different months, 2019 to 2021.
What it is
Lecture 2 of MIT's 5.60 Thermodynamics & Kinetics (Spring 2008), taught by Moungi Bawendi and Keith Nelson. It covers work, heat and the first law, including temperature scales, the ideal gas thermometer, reversible processes and p-V diagrams.
What people said
Recommends chr218 · 2021-01 · Physics Stack Exchange · on “Where does the unit kelvin come from?”
Because I do not have enough reputation points to add a comment, I have replied using an "Answer". Consider Lecture 2 of MIT thermodynamic course 5.60 [ [this video] ] The Kelvin unit was formed due to the inconsistent reference points of the Fahrenheit and Celsius temperature scales. After the discovery of the ideal gas relationship, it was instead suggested to use the limit of the Ideal gas law as pressure approaches zero, which would act as a consistent, but hypothetical reference point for temperature. In short, I believe it is due to the historical aspect of temperature scales. The Kelvin scale was developed before stat-mech.
Cites Vishal Jain · 2019-10 · Physics Stack Exchange · on “Why is the Kelvin scale formed using the triple point of water rather than the freezing point?”
I am trying to learn some thermodynamics by watching the lecture series on YouTube by MIT. In the second lecture [this video] , from 9:00 to 9:45, the lecturer talks about why the freezing point of water as defined in the Celsius temperature scale would make a bad second fixed point (the first being absolute zero), to use to interpolate between and create the Kelvin scale. This is because apparently water doesn't boil at 0 degrees everywhere, it depends on the pressure being 1 atm. He then goes on to say it's better to use the triple point of water instead. This doesn't make sense to me since the triple point of water is only 0.01 degrees at 1atm, just as the freezing point is only 0 degrees at 1
Cites Clemens Bartholdy · 2020-09 · Physics Stack Exchange · on “Deriving ideal gas law from Boyle and Charles”
You can't derive it like that because the proportionality relations hold only when the third parameter is kept constant. However, you can derive the ideal gas law by noting that for high temperature, we get a limit as shown below: $$ \lim_{ p \to 0 } p \overline{V} = f(T)$$ So, the limit of the product as pressure drops to zero is a unique function $ f(T)$ for all gases independent of the substance used. We can use this to define the linear kelvin scale. Using the triple point of water and absolute zero as our reference, $$ f(T) = \frac{f(T_{trip-point})}{273.16K} T$$ Where $f(T_{trip-point})$ is the value of the limit at the triple point, using this and our first equation, we can write, $$
Cites Clemens Bartholdy · 2020-09 · Physics Stack Exchange · on “Interpreting phenomena as heating or cooling in the $p$-$V$ plane”
At 43:40 of this video lecture [this video] , the instructor interprets the path along $p$ - $V$ curve as cooling and I don't exactly understand how he inferred this. It's quite obvious if you introduce in the gas law, $pV=nRT$ but the context was about general gases, so what is the general way of arguing that it would be cooling with the basis of some property more general?
Cites Clemens Bartholdy · 2020-09 · Physics Stack Exchange · on “Defining the Ideal gas thermometer”
At 2:22 of this video [this video] , the prof. Moungi bowendi motivates the ideal gas law by saying that $$ \lim_{ p \to 0} p \overline{V} = f(T)$$ That is if we drop pressure and see how it changes the volume, keep multiplying the two quantities and find the limit, we would find that it always converges to some constant dependent of the temperature of the gas. My question is, how exactly would we pull this of practically? Every time we change the pressure, we implicitly change the volume as well if the temperature is fixed. So, if all gas converges to the same the same constant at a given temperature, how would we do verify this because as we change the pressure the molar volume is also changing
Cites Clemens Bartholdy · 2020-09 · Physics Stack Exchange · on “How would our equations of thermodynamics change if we choose a non-linear interpolation for the kelvin scale?”
At 5:31 of this video [this video] , professor Moungi Bawendi says that we could choose any kind of interpolation we like for the temperature scale, and all of thermodynamics would still be 'functionally' the same. This got me curious, for how the thermodynamic relations such as the ideal gas law and others would change as a consequence of this.
Cites Clemens Bartholdy · 2020-09 · Physics Stack Exchange · on “What dependence does reversibility have on the time taken to change state of a system?”
In this video lecture [this video] , at 39:37, The professor describes that if we do the process slowly then the system moves through a set of equilibrium states but why exactly does the speed of doing the process effect reversibility ? For an analogy, take that video itself, if I play it at 1x or 2x speed by changing the Youtube settings, still the ultimate thing which plays out on my screen would be exactly the same.