
Ask HN: How can I start learning physics? - J-H
Hi, 
I'm a high schooler who wants to learn physics but our high school doesn't offer anything past a very beginner physics course. How do I start learning - Khan Academy? or something else? Tips from anyone who learned physics thoroughly? I'm looking for something free or pretty cheap (so not really print textbooks)?
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ninthfrank07
I recommend you the "Intro to Physics: Landmarks in Physics" course made by
Udacity (<http://www.udacity.com/overview/Course/ph100/CourseRev/1>). I'm
currently halfway through it and I'm having a lot of fun doing it! Here's the
syllabus of the course:

Unit 1: How can we measure the circumference of the Earth? Basics of geometry
and trigonometry

Unit 2: How do objects move? Data analysis and kinematics

Unit 3: What causes motion? Forces, acceleration, and Newton’s Laws

Unit 4: How can we use motion? Work, energy, and simple machines

Unit 5: How can we determine our longitude at sea? Simple harmonic motion

Unit 6: What is electricity? Charge and electric fields

Unit 7: What is left to discover? Modern physics and open questions

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masterzora
<http://www.staff.science.uu.nl/~hooft101/theorist.html> is a great starting
point. That page is written and maintained by a Dutch Nobel Prize winner who
believes that it should be perfectly possible to learn physics from the
internet if you know what you're looking for. If you go down the page he also
includes references to print texts but the idea is for the web links to be
sufficient.

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mhartl
I taught the physics core curriculum at Caltech for five years, so I'll do
what I can to help. For many of the classes at Caltech, we never found a truly
satisfying textbook, but when you're learning on your own that's still the
route I recommend. This means putting textbooks back on your list for
consideration. Buying a textbook for a full 1-2 year college-level physics
sequence costs less than $200, _much_ less if you buy used. You have parents,
right? Now they know what to get you for your birthday.

Your immediate goal should be to get a firm grounding in classical physics,
which will be important for everything else you do. When choosing a textbook,
the most important thing is to pick one that's aimed at scientists and
engineers. That means it should be calculus-based, "algebra-based physics"
being a contradiction in terms. If you don't know calculus, you should start
there. (This will set you back some more money. Sounds like a plan for
Christmas, Hanukkah, etc.)

To my knowledge, none of the introductory texts are truly great, but I did
some poking around and _University Physics_ by Young, Freedman, and Ford looks
like a good bet. If you need to learn calculus, _Calculus_ by Larson and
Edwards looks decent. Get the most recent editions if you can afford them, but
I'm sure older editions are fine. Those two books alone should take you a year
or two to consume, and they are likely to be _very_ challenging unless you
have an exceptional preparation in mathematics. But even if you get stuck
occasionally, you'll still be _way_ ahead of the curve. (I wish someone had
put a calculus-based physics textbook in my hands when I was in high school. I
would have been _unstoppable_. Unfortunately, though it now seems impossible,
I went to high school before Amazon or even the Web, so it simply never
occurred to anyone.)

I recommend supplementing the textbooks with liberal use of Khan Academy
videos and Wikipedia articles. More than anything, it is essential to solve a
large number of exercises. Developing a good physical intuition is important,
but physics is a quantitative discipline, which means being able to do
calculations.

One more thing: if you want to demonstrate your competence to the world (and
to college admissions committees), it's a good idea to take the AP Physics
exam (B or C) at some point. The AP Physics C exam is the best one to target
if you only have enough time to take one, as it will let you test out of
introductory courses at many schools. (Not at Caltech though—we have a
separate system of placement exams.) Take a look at the AP Physics C website
to see the syllabus. If you decide to take the exam, buying a test-prep book
such as _5 Steps to a 5 AP Physics B &C_ is probably a good idea. If you go
this route, try to negotiate with your school to get course credit for your
independent study.

P.S. At some point, read _The Feynman Lectures on Physics_. FLP doesn't make
for a good introduction, but after you have a foundation it's gold.

~~~
khyryk
I used Calculus (4th edition) by Larson, Hostetler, and Edwards for my calc 1
and 2 courses and I would not recommend it for independent study.

Consider Calculus by Briggs and Cochran instead (
[http://www.amazon.com/Calculus-Early-Transcendentals-
Briggs-...](http://www.amazon.com/Calculus-Early-Transcendentals-Briggs-
Cochran/dp/0321570561/ref=sr_1_1?s=books&ie=UTF8&qid=1344038334&sr=1-1&keywords=calculus+cochran)
) for good explanations with example problems and for the superior images,
which are particularly helpful for multivariate calculus.

~~~
manglav
Another calculus and all around math guide is here for free.
<http://tutorial.math.lamar.edu/> I've been using it ever since I was in high
school. To this date, I have only rarely had to pay attention in my math
classes due to this resource. This will take you to calc 4 and even cover
linear algebra. The best part is he progresses in a methodical way, everything
is downloadable in pdf format, and his examples are great.

For physics, the Feynman lectures are a great once you have a bit of
foundation, but really any course from MIT OpenCourseWare or Coursera will do.
The key is definitely doing examples, and I find it is particularly useful to
apply it to real life by asking questions. Rainbows? Cameras? Bubbles? Spear-
fishing? All great examples of optics. Deep sea excavations? Pulling out the
Titanic? Diesel-filled bags? Perfect for studying bouyancy and forces. Have
you played Tanks? (seeing as you're in high school, I'm sure you have. If not,
you should!) Projectile motion! Just keep your eyes open.

Since you're doing it on your own, I highly suggest learning physics Calc
based, instead of algebra based. Everything will tie in very nicely, seeing
how calculus was apparently invented FOR physics (courtesy of Professor
Covault at CWRU).

Kudos, and good luck!

edit: After trying to use Wikipedia for physics in college, I don't recommend
it if you're trying to learn. They use weird terminology, and sometimes weird
notation. Sometimes it is good for examples though. Also, check out the
International Baccalaureate exams, an alternative to AP. The main difference
is that AP expects lots of breadth and little depth, vs IB is vice versa. My
physics teacher used to say "IB wants you to be able to answer a question the
same way someone with a PhD in the field would". You can find practice exams
online. By the way, for Higher Level (HL) exams (equiv to C-level in AP),
around a 65% is a 7, the best score you can get.

edit2: Don't forget public libraries! Especially at large colleges or
universities. They have many textbooks available, even the old ones at times
(which I prefer, there's something about picking up an old textbook and
learning from it that's not captured anywhere else. It feels like you're
learning from the major players in the game, and I get more motivated to do
well). I'll stop with the edits now.

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bcuccioli
Depending on how ambitious you are, for a more rigorous introduction to basic
mechanics I recommend Kleppner & Kolenkow. Though if you choose to start with
a more basic book like University Physics I strongly recommend K&K as a second
book. This assumes you have passing familiarity with calculus.

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joshlegs
You could always take the Newtonian approach and just sit under an Apple tree
...

~~~
vitus
And develop calculus, no less :)

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codeonfire
You can get University Physics 11th edition, which mhartl suggested for about
$35 used.

This will be about 1500 pages and 40 chapters. If you do a chapter per week
with problems, you will know basic physics in 3/4 of a year. However, you're
going to need to learn calculus as well, so pick up a used calculus book.

This is by far the cheapest route. A couple of books, some paper and pencils.
My problem with online video courses are that they are SLOW. They take a tiny
bit of subject matter that would fill a single page and stretch it out to a 45
minute video. It's far worse if the teacher is a slow speaker. A good solid
book is open road, fast as you want to go learning.

