### IB thermodynamics: FAQ

Send me questions, and I'll answer them here. I've put them in rough order of how often I am asked.

Q1. What sort of question can we expect on the exam?

The thermodynamics part of the physics paper will have 3 quickie questions (like section A), 2 longer questions (a la section C on last year's exam) and 1 essay/notes question. I forget, or rather have no clue, how much choice you have among all the questions. Probably the examiners are debating that issue now, since the whole IB course is new this year.

Q2. How can we decide what quanities we can take for granted to estimate values? I do not remember any sets of numbers, such as the energy required by a person in a day, ionisation energies, energy in food, etc. I look them up in books, or on the packets, etc.

Good question. The fewer quantities you look up the more you will learn, but don't torture yourself. If you do look up a value, think how you could have figured it out.

For example, an ionization energy may be a horrible value in Joules. Convert it to eV and you'll find that it's maybe 4-10 eV. How could you know that? Visible light photons are about 2 eV and they don't ionize most substances, whereas UV light does. So ionization energies are somewhat bigger than 2 eV, and 4-10 eV is plausible.

Q3. This estimation is fun and all very well. But will we get steamrollered on the exam by regular questions?
Q4. What is with the sign you wear?

It says "Oiligarchy" in big red letters, derived from oligarchy or `rule by the few'. I added the "i" to say that the Iraq war shows we (the Americans directly and us indirectly) are ruled by a few oil men. Since physics enables America and Britain to invade and rob Iraq, as a physics lecturer and an American and British citizen I feel a triple obligation to protest.

Q5. But by wearing the sign, aren't you making a political statement in lecture?
Q6. Is Equilibrium Thermodynamics (also by Adkins) a suitable replacement for Introduction to Thermal Physics?

No. It is long, abstract, and abstruse. I don't know 90 per cent of it myself and I am a happy guy. But here is an alternative to Introduction to Thermal Physics.

Q7. Have you ever seen a jam-filled torus donut, and if so where? I want one.
Q8. This estimation is fun and all very well. But don't we need to know exact calculations? I thought physics was an exact science.
Q9. I have heard that thermodynamics is the most fundamental of all the physical theories that describe the world: the second law is times arrow and all that jazz. Will you convey this fundamentalism of the ideas to us in the course?
Q10. Would anything actually have to be learnt to do estimations, or is it just ways of thinking?
Q11. If we will not do much formal material, what is the purpose in attending the lectures?
Q12. Secondly, why is your course called Classical Thermodynamics? It seems you are teaching a course on "thinking in physics" with a slight thermodynamic twist.
Q13. The purpose of "equation pushing" (as you put it) in lectures is so that you can be fed the information, and in your own time make of it what you understand it to be. What is your opinion on this idea?

I think it's a waste of taxpayer (e.g. your parents') money to pay me to feed you equations when you can get them in a book; and a waste of your time when you can read the book on your own. Most people learn from examples; then once the pattern is understood, by formalizing it in an equation. If the equation comes first, it too easily turns into symbol pushing because the knowledge is not backed by examples. If you understand the examples and why they produce the equation, then you can always rederive the equation. That's why I emphasize the habits of thinking useful in any problem. You still have to spend a lot of time on your own struggling with the material, but you'll hopefully do that based on an intuition for the subject.