Question

How do you effectively study physics? How does one read a physics book instead or just staring at it for hours?

(Apologies in advance if the question is ill-posed or too subjective in its current form to meet the requirements of the FAQ; I'd certainly appreciate any suggestions for its modification if need be.)

Answer 1

Here some suggestions pulling together various strings from this site and others and adding in my own thoughts. Check it though - some is way over my head:

Be clear what your goal is
an intuitive understanding of the functioning of the world around you (as well as further away) or
the ability to solve complex problems (or even breaking some new ground- that's something I won't even tackle here). Doing hardcore physics means you'll have to get deep into maths but this won't give you much for the intuitive understanding (or at least it's the much more laborious route).

Don't get too excited about trendy topics (string theory, quantum mechanics and special relativity) before you have a decent grasp of fundamentals in mechanics, waves and electromagnetism. Maybe you really have found that the uncertainty principle does not hold but everybody will think you are a clown if you don't know the basics of kinematics (and a bit more than that). And "Let's talk about string theory" is no longer that interesting as a pick-up line.

Accept that you don't have to understand everything at once. If you don't get it after you have spent some work on it - just memorise it and get on. Sometimes (mainly for conceptual issues, like wave particle duality) understanding basically means getting used to something. Other times, you may just have a block and you'll get it when you come back. But if you find yourself later knowing all the math but understanding nothing about the physical meaning of it, you should go back.

If you are keen on the intuitive understanding, try to see the physics in whatever you are doing (why are you not falling through the chair). Do thought experiments, like whether a variable can rise to infinity (or fall to zero) and think what would happen. All this can be good fun with like-minded people - so get social on physics (I am afraid hardcore physics won't get you much social life, by contrast).

Even if you are not in for hardcore phyiscs, get a modicum of maths. You may find it tough talking about physics to physicists without knowing the basics of calculus, for example.
If you are keen on hardcore physics and you don't have a strong quantitative background, fixing your maths weakness is probably more important than getting to know any physics.

And then solve problems. There are plenty of sources for problems. One (free) option is looking through past exam papers.
The UK exam boards for A-levels (approximately the same as advanced placement in the US) are publicly accessible and not bad - though not structured by topic. The AQA (one of the boards) papers are here.
Ohio State University has compiled a fair number of practice problems for the Physics GRE.
Even more advanced, Columbia University has a list of past exam papers that physics graduate students need to get through before they start their PhD research.

Boost your fluency with adaptive learning. Toktol physics (note - I am working for this site, still being expanded quite a bit) uses questions (up to lower university/Advanced Placement/A-level, covering pretty much the full curriculum) in a sequence adapted to one's ability, and spaced repetition to help people learn physics (and maths) as quickly as possible. Pearson and some other publishers also have online learning tools for physics but they tend to come with books or are only accessible for members of a class (e.g. Pearson's Mastering Physics).

Get the right books:
The books tag on the (physics stackexchange) has many good lists of books for different purposes, and a community wiki post on books questions does a good job of pulling them altogether (including lists of free books).
On the more hardcore side, physics books that are not targeted at physicists but at engineers or other disciplines where physics is an auxiliary subject can be quite good shortcuts (they are more focused on getting down to the matter). Another post mentions Physics for scientists and engineers by Randall D. Knight and I have nothing better to suggest.
On the simpler side, "Physics" by Tim Kirk and Neil Hodgson (for International Baccalaureate) is very thorough and also covers the trendier topics as optional sections. Conceptual Physics by Hewitt (targeted at US undergraduates, probably more at the less demanding side of the spectrum) is very soft on your maths muscles and pretty good at explaining.

Get the intuitive understanding by watching to some good video lectures.
Video lectures by Walter Levin (physics emeritus professor at MIT and a rock star of physics education) are extremely accessible (partly because of his stunt-like experimental setups) but very sound throughout.
The Physics for Future Presidents lectures (Berkeley) are also great for an even more casual introduction to physics.
There are more demanding (university-leve) physics lecture videos at Berkeley and MIT.
Khan academy shows videos of Sal Khan, another educational rock star, explain physics (as well as maths and other stuff) by writing on a tablet.

Lecture ppts and lecture notes are informal and very focused on making the core points (that can be lost in massive books) and that's also what newcomers should focus on, so they are well worth looking for. Google, say, for ppt "escape velocity ppt" or "p-n junction pdf" will give you massive results. Flipping through those docs will get you some new visual ways of understanding concepts.

If you like playing with simulations, there are quite a few online free projects listed (but in a not too accessible way) by the US Department of Education. The University of Colorado has a good number of physics simulations, though again it is a bit tedious to go through them. Playing with such simulations will again building your intuition.