PHYS 1305-07 - Elementary Physics Revised Fall 2003

On Studying Physics

Physics can be described as the study and use of basic principles to solve problems. At the professional level, this can be "pure," research into either new or little-understood phenomena in order to understand what basic principles apply to them; very often such work is as hard to describe as it is to do, because the phenomena involved are unfamiliar. Or physics can be "applied," research into how principles we already understand can be used in new situations or new devices. Often these categories blur, as when a "pure" researcher wants to measure something that hasn't been measured before; designing a suitable tool will be applied physics. Or an "applied" researcher has to determine and understand why the new device didn't work quite like the plan; some new phenomena may need to be investigated. In either case, physics is contrasted, at least in principle, with engineering, for which the description is the use of established practices to solve problems. In the real world the distinction may blur, depending on the problems involved; when anything arises that's not covered in "the book," an engineering job turns into physics.

For you as a student, this means that we will try to get you to learn at least some of the basic principles that physicists have developed. They were developed in response to problems, in order to solve future problems. You will see, and probably ought to work, lots of problems; the point is not to give you lots of details to learn but so that you can see that a short list of principles can handle a long list of problems - one hopes, even the unpredictable problems that you will some day face, on the job, that your courses did not cover. A substantial part of your grade will be determined by how well you can do problems in a test situation.

Physics began with simple situations; this text and this course stick mostly to simple situations. But not everything is simple in the way "common knowledge" would have us think, and some test problems involve cases where "common knowledge" overlooks an important part. Others may test something as simple as distinguishing the physics use of a term from everyday use of it (usually the everyday usage is a looser, less useful meaning).

The purpose of tests is to see if you have learned at least some of what you were supposed to. In a physics course that learning is not straight memorization, it involves understanding of basic principles and especially of how to apply them. The reason physics is required, by most curricula that require it, is that people in that field believe it is important for you to understand these principles and be able to use them in new situations - the situations that were not covered in your courses. The only way to test if you have some degree of that ability is to give you test problems that call for you to apply your knowledge in a new situation, or at least one that is at least somewhat different from those that were previously discussed. Unfortunately this calls for a skill which may not be teachable; the only way I know to acquire it is practice, on as varied a problem set as needed. (If you have trouble, repetition with variations may be an answer, and is the reason that most physics textbooks have long, varied, lists of problems. However, working the same problem a second time will not be good practice, since it will no longer be a new situation.) Countering the necessity of a possibly unteachable skill as a requirement for physics, is the fact that not mastery of that skill, but only some capability for it, is required for progress in physics; since I curve grades, less than 40% of total possible points has been known to be a passing grade.

The problem lists in this text are relatively short; I expect that a reasonable minimum practice would be to do all the odd-numbered "Exercises." Answers for these are in the back: you can determine almost immediately if you agree with them. Caution, however: it is not at all unprecedented for textbooks to have typos even in "well-checked" answer sections. No one but you will evaluate your work on most of these, but they will provide examples for lecture discussion. Test problems should be comparable. Look also at the "Challenge Problems" and "Home Experiments and Observations" sections, beginning in Ch. 2; they are more good practice.

The approach to learning this material that seems to work for most students that try it is: read, then work problems before class, then in class ASK QUESTIONS. First, read the text, seeing if it seems to make sense. Then read and think about all of the "Questions" that the author places before the "Exercises." If you understand the material, they should be easy; if you don't see what they're getting at, then you missed something: find it. Now try some "Exercises." If they give you no difficulty, go on through the list. If a single problem gives you some difficulty, try another before spending a lot of time on one: just a change of context might be enough to let you recognize what you missed on the first try. As a rule of thumb, if you have spent half an hour on a single problem without making progress, it's time to look at a different one. (A long problem may require more than half an hour simply to work out the details; that's wht I indicate 'half an hour without progress'.) At whatever point in the above sequence you encounter difficulty, you have identified something to ask about in class. Continue reading and noting questions through the chapter; you may even find that some later application of the concept answers your early questions. Now attend the lecture, and ask your questions. After lecture continue with reading and problems. When no one asks questions, the lecture may go smoothly but not as much learning may occur. (Rereading before you try problems is probably not going to help you understand: it is the examples and problems that show what the author is talking about, much better than his words alone can.)

Quiz/test problems will be mostly story problems and will require thinking; knowing formulas will not be enough. It may sometimes not be obvious where to start in order to arrive at the required answer, while in many cases information will be provided that seems related but is not actually required. Those are reasons why a variety of practice is recommended. One hint: If you don't see how to get the final answer for a particular problem, but do see how to get some addtional values, do that and then look at the overall problem again with the new information. On quizzes, each problem will relate primarily to a current topic but may require additional steps based on previous material; on the final the same applies except that the topic and the extra steps can be from any part of the course.

If you have had trouble with University College math classes, you may have some trouble with the work in this course. On the other hand you might come to realize what that math stuff is good for and thereby finally catch on and remember how to use it.

If you are looking for more practice, almost any text or study guide labeled Physics, without a subfield modifier, should provide some help. (If the label is Atomic Physics, for instance, it won't help.) A book labeled Conceptual Physics or Elementary Physics will probably be at a similar level to ours, or lower; a book labeled College Physics will assume you know trigonometry; while one labeled University Physics, Technical Physics, or Physics for Engineers, or the like, will usually assume you are learning some calculus. If those latter are available but you haven't had that math, just read around the math: the concepts are the same, they are just being more rigorous about the details and the real-life type complications (like forces that change, for instance). Many (of course not all) of their problems will be similar to ours, not using the math power. (The reason a strong physics course will require a lot of math is not that we're being hard on students; it's because it takes that kind of math to handle full-fledged physics problems. In fact most of that math was developed because physics needed it, not for purely-mathematical reasons.)

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