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?
Q4. What is with the sign you wear?
Q5. But by wearing the sign, aren't you making a political statement in lecture?
Q7. Have you ever seen a jam-filled torus donut, and if so where? I want one.
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?
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.
The section A questions will be like the shorter examples we do in
class, e.g. estimate the heat of vaporization of water by any
reasonable method. The longer questions will be like the longer
examples from class, perhaps explaining a bit of everyday physics,
perhaps even using an equation or two, maybe even an integral (once
entropy appears, which will be soon, integrals are hard to avoid). As
for the notes/essay one, I don't know. But you'll have practice with
all the types in the problem sheets and I will submit questions for a
mock exam.
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.
If you analyze each quantity after you look it up, you'll
eventually learn them, and remembering them will not be an
issue.
No. I propose the exam questions. The examiners have final
say (`final responsibility for the exam
rests with the examiners' is the official phrasing), but I will propose
questions like what we do in class and on the problem sheets.
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.
Yes, and feel free to agree or disagree with it. Political
statements are hard to avoid. Many people wear clothes with a Nike
logo, thereby supporting a company that subcontracts to factories
paying children sub-poverty wages. (If I wore a T-shirt with a large
"Oiligarchy" logo, many would think it is more acceptable than wearing
a sign, because T-shirts are a more normal form of dissent. But I
don't want to paint a sign on all my shirts!) Or look at the
convention that lecturers dress nicely. Many, including me sometimes,
wear a jacket and tie. As a class-based dress style, it too makes a
political statement.
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.
In my naive youth (i.e. until Jan 2004), I thought that all jelly
donuts were filled with jam. Now I know better. In American jelly
donuts, the jelly is a torus inside the dough torus. In America, you
can also get cream-filled donuts. It is the land of the free, at
least if you are hungry for topologically correct donuts. Yet another
reason to go on the MIT exchange!
Exact calculations are dull. Sometimes you have to do them: for
example, a conservation law accurate to a factor of 2 is not useful.
I'll do a few exact, legitimate calculations to please the physics
gods.
However, most of the Cambridge physics course emphasizes derivations and
exactness. This lecture course is an exception, as is my Part II
course and Malcolm Longair's Part II course, and is a chance to
apply physics to the world around you. The world is messy so
approximation is necessary. And it's fun.
I will try. We will soon discuss the second law. No matter how much
one discusses it, it is mysterious. Just like the double-slit
experiment in quantum mechanics.
From strictly classical
thermodynamics, the second law is empirical. You've never seen it
violated (for example,
teacup shards do not unshatter themselves and jump onto the table as a
teacup), so
you assume it is a law. To understand it more deeply, you need
statistical mechanics, the subject of the following course taught by
Bill Allison. Meanwhile see the beautiful book, The Second
Law by P.W. Atkins.
Both! I am trying to show that good ways of thinking allow you
to do most of thermodynamics, so you have little formal material to
learn beyond good ways of thinking. The formal bits include, for
example, the thermal flux equation (with thermal conductivity),
entropy and adiabatic versus isothermal expansions, but I am more
interested in the ways of thinking than the formal material. Plus
much of the formal material is derivable from ways of thinking, as we
are doing with the thermal flux equation.
To practice using and arguing about physics ('speaking physics') --
like the way you become fluent in a language. For example today, to
find many different ways of estimating the heat of vaporization of
water, each including a different piece of physics. Almost no
textbook teaches the art of approximation, so for now it's learnt in
lectures by participating in it and also seeing what I do. Another
purpose of lecture is to practice explaining and defending your ideas
about physics. That's how physicists spend their days and make
progress. Lecture isn't the only place to get that -- you can argue
with other physicists in your college, but lecture is also one place
to meet physicists outside your college.
That is mostly right. I think most important to learn are the
confidence and methods to fight your way out of the jungle. I happen
to be teaching Classical Thermodynamics, so I'll use examples related
to energy, power, flux, and a bit of entropy, in order
to teach those habits of mind.
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.
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