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What is the real point of Intro Physics?

  1. Nov 1, 2009 #1
    I'm almost finished with my first years of physics and I've noticed a few things. Granted each school is different but people out there with some more insight can perhaps clarify.

    1. Even for an interested student of physics there seems to be far too much material covered over these courses that anyone can actually be expected to retain all of it in a meaningful way. I am contrasting here with my math courses where ideas are introduces and covered nearly to the full extent before moving on. I suppose that this is the function of higher level courses in physics but it seems rather odd to me.

    2. Most of the stuff we are learning in intro physics is explained away with weak explanations. Sometimes situations are made so idealized that you begin to wonder the point of study them, other time the explanations are simply glimpsed over. More often than not most of what we are learning is not even really true anyways.

    So I guess my question comes down to

    1) Who are these classes really for?
    I think that for a physics major a course at a slower pace where things are shown in greater depth the first time could be sufficient. For a non major, why not just get them acquainted with some of the interesting concepts of modern physics?

    2)Are there any alternative ways to teach intro physics?
    I really think this stuff I spent nearly a year knocking about learning I could have handled in much less time and I could have gotten onto the parts of physics I care about and have interest in. Clearly the fundamental ideas are needed (work, conservation principles,etc etc) but that can probably be covered pretty quickly and easily in addendum to a course that starts with no previous knowledge of physics and goes up to say junior year mechanics?

    My guess is that the whole thing is really a result of the math preparation of students not really being up to the level of being able to do proper physics until a few semesters in and that these courses are just kind of "busy work" until you get your maths up?

    Feel free to move this to Gen. Discussion if it is more applicable there.

  2. jcsd
  3. Nov 2, 2009 #2


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    Really? Can you give an example?

    In what sense is intro physics not "proper" physics?
  4. Nov 2, 2009 #3


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    I think an important point of intro physics courses is to allow students to forge their physics intuition.
    As you know, many people do bad in these courses so skipping them for advanced courses wouldn't be beneficial to the majority of students. Only very few students could possibly do well in advanced/intermediate courses without having took the basics.

    These intro courses are also important because they're the emerged part of the iceberg you'll discover in the next years of your Bs. In my opinion, if you didn't find anything interesting in the intro physics courses, there is a big probability that you won't like what's coming next, namely Modern Physics, EM, etc.
  5. Nov 2, 2009 #4
    You are supposed to retain most of it or your later years will get very hard. Things goes faster and faster, not the other way around.

    I find it funny that on one end you say that you want the course to be smaller/faster, and on the other you say that you want them to go through the material slower... Also while most of the classical physics is important for a lot of non physicists modern physics is for the most parts not useful at all which is why it isn't taught this early. Also you can barely do any modern physics till you have learned a lot more maths than you know as a first grader.
  6. Nov 2, 2009 #5
    The tip of the iceberg is pushing wooden blocks down ramps (as fun as it may be)?

    For any physics major, this surely is the most boring part of the iceberg.

    The OP made a comment about being taught physics that's not "even really true anyways."

    This is true. In fact, I had to argue with a teacher that his question was faulty, and, after I explained to him why, his only response was "We haven't covered that yet." What's the point of putting WRONG physics, whether it was covered or not?

    A lot of the math they do is pretty sloppy too.
  7. Nov 2, 2009 #6


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    Care to tell us what this wrong physics is?
  8. Nov 2, 2009 #7

    Andy Resnick

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    We have several versions of "Intro Physics". There's the calculus-based version (with a second subtype for "honors"), there's the algebra-based version for non-majors who need it the degree requirement, and then there's a couple of 'physics for poets' classes (one is 'the flying circus of physics' and the other is 'energy and society').

    I'm currently teaching thealgebra-based course, and the State of Ohio has a list of topics I *must* cover (actually, a long list of topics and a dictum that I cover at least 85% of the topics)

    As for question (1), having a given list of topics does not prevent covering some modern physics. For example: "collisions and conservation of momentum", and the worked example I use is the discovery of neutrinos.

    While I understand your frustration, I am also reminded of a saying (I forget by whom) that goes something like:

    "Physics took over 2000 years to develop, and our students expect to learn it all in 4 years"
  9. Nov 2, 2009 #8
    Just to clarify I'm not saying I dislike these courses or don't find anything interesting but my question is WHO are there classes for? For someone sufficiently motivated and interested in physics I think a more in depth course dealing with individual topics would be better. For a non physics major a more qualitative course is probably fine. The current "intro physics" seems like a bizarre bridging of the two that doesn't really do that well for either group of students.

    When I talk about the pace I'm comparing it to typical math courses where you cover a few related topics in depth for a week or so before moving on. At least in the classes I've been in there is so much material that a good chunk of it ends up being ignored by the professors and students alike. Personally I just prefer the approach of learning a topic to its bitter end right from the get go and having to make all these qualifiers about various properties and formula because there is alot more going on in a seemly small topic than is covered in a single chapter/week of intro physics.

    If physics classes continued just as this I probably wouldn't be interested in it for a major but I know that isn't the case, contrary to the opinions above. If you professional physicists did get excited about a block moving up a ramp or the current is a simple circuit than I guess I am a lost cause.

    Wasn't this issue pretty much why Feynman came out with his lecture notes, because people who get excited about physics as a career end up somewhat bored by the intro stuff? I remember hearing that somewhere?
  10. Nov 2, 2009 #9
    As for physics not being "true," I think he means for example how newtons law of gravity is not totally accurate in all cases, or how projectile motions ignores everything except gravity at this level, ohm's law, etc.

    Nonetheless everything taught in these courses is still useful and at a minimum they further develop your problem solving ability. As you develop greater mathematical maturity you will be able to solve more intricate problems. What is your mathematics background like?
  11. Nov 2, 2009 #10
    I just realized that we need you to link to a page with your course description or such? Just hearing "intro physics" and not much else doesn't give a good explanation of what you are actually studying and until then it is impossible to answer your question.

    As it is now it seems like you study the physics that I did in middle school, which indeed would be boring at a college level.

    But where I study we start with thermo the first thing we do, then after that electrical circuits, after that basic em/wave theory and a mechanics course. During this time we also do one variable/multivariable calculus and linear algebra. But at least here you are forced to have studied some calculus before you apply, or the thermo course would be impossible. So I think that I do not really know what your "intro physics" is at all, just assumed that you studied roughly the same things the first year.
    Last edited: Nov 2, 2009
  12. Nov 2, 2009 #11
    Which of these graphs is the correct velocity vs time graph of a ball falling of a cliff?

    The answer was a graph with a positive-sloped line. That's just wrong. The ball achieves terminal velocity at some point. Even if it didn't achieve at one point, the line would still be disfigured towards the end, showing the effects of it converging to a terminal velocity.
  13. Nov 2, 2009 #12
    It depends on the height of the cliff, the speed the ball is pushed off with and its density. In most cases you don't get close to the stable velocity, and remember that the forward speed would decrease too making the effects much less noticeable on the travelled line.
  14. Nov 2, 2009 #13
    Exactly my point. The velocity wouldn't just uniformly increase. I could see it doing that at first, but very shortly after, it would not be linear.
  15. Nov 2, 2009 #14
    Ah, I thought you meant a trajectory but if it was a speed diagram then I completely agree with you. Ah sorry, misread then. They should have said "On the moon".
  16. Nov 2, 2009 #15


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    I'm sure it was a simplified problem, like neglecting air's resistance. What you get is an approximation of a real life problem. Calling "wrong physics" at approximations (although I agree in this case it is a not really realistic simplification) is not really nice. Most if not all "real physics" problems might be solved by approximations.
  17. Nov 2, 2009 #16
    There are a lot of reasons for having intro physics classes.

    1) Builds intuition, teaches the way to think the a physicist in terms of how to simplify and accurate model things. (i.e. to teach students about the spherical cow :))

    2) Gives a survey approach to mechanics and electricity and magnetism which is good for students who are not going on to any more advanced physics. Engineering students, for example will typically take these two classes and then take specialized classes in their fields.

    3) Students simply don't have enough mathematics to go any further in depth in topics. Typically most students have only taken or are taking calculus I/II while learning physics for the first time.

    4) Not learning everything or being able to explain everything adds to the excitement of the subject in my opinion, I'd like to think it inspires people to further their physics education.


    Without an intro level class would you still be interested in physics? I know that's what did it for me. If I had not been forced to take physics in high school I certainly would not be interested in it now.

    As for Feynman's lectures for people who have not taken physics before, the lectures are said to be confusing and it wound up that more professors than students attended the lectures he gave.
  18. Nov 2, 2009 #17


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    There are several reasons such a course is offered
    -Justify existence of physics department
    -Generate revenue for physics department
    -Encourage persons to enroll in physics in furtherence of above
    -Justify staffing of physics department

    Thats about it really
  19. Nov 2, 2009 #18


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    One point that I don't think has been mentioned so far is that often the first year "introduction to physics" course is used as a normalizer. Students from different high schools are all coming into university with different experiences. Some have had great high school teachers who have prepared them so well they would be fine to enter upper year classes. Others have never been told what a vector is. And yet they can come in with approximately the same marks.

    So the first year class tends to cover a lot of material quickly because a lot of it will have already been covered - for most of the students. When you look back on it, first year physics won't seem all that different from that covered in the twelfth grade.
  20. Nov 2, 2009 #19
    I should point out that you may be in a situation where the class may just be taught badly.

    This is partly the result of the fact that a lot of the ultimate explanation of things is "well that's the way things work?"

    You need to study idealized situations because usually if you study non-idealized situations, things get so nasty and complicated than it's hard to see what's really going on.

    Very little in physics is "really true". Anything real is going to have some approximation of some sort.
  21. Nov 3, 2009 #20
    But approximations is what brought us to where we are today :)

    Everything you do are approximations, but as long as the error is small enough then you don't even notice that it was there. The reason people are not taught about air resistance is because air resistance has a very ugly formula and it is pretty much impossible to do any proper calculations on it and even then it is far from exact since we do have a lot of turbulence etc.

    If people were only happy with exact solutions we would have stayed back at the stone age.
  22. Nov 3, 2009 #21


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    And some never took physics in high school. :bugeye:

    (This may be hard to believe if you're not from the USA...)
  23. Nov 3, 2009 #22

    Doc Al

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    This reminds me of my first day of Physics 101 as an undergrad physics major. The professor peered over the class and asked "How many of you took physics in High School?" I'm sure every hand was raised. Then he nodded and with a slight smile said "Welcome to your first physics class".

    (He was right.)
  24. Nov 3, 2009 #23
    You have to start somewhere. Most freshmen are not ready for a real class in classical mechanics, which requires good skill in multivariate calculus and differential equations. Physics is taught by starting with the most simple situations and then generalizing.

    It is true that freshmen physics often puts together students with a wide range of ambitions and abilities, i'll give you that. Just use it as a chance to get some good marks, it will get more difficult soon enough.
  25. Nov 4, 2009 #24


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    If you think intro physics is covered too quickly with too much content, you should try an intro biology course! :biggrin:

    All of the intro courses are general surveys to provide some basics and an overview of what to expect in the more advanced courses.

    They need to be somewhat complete, at a superficial level, for the sake of those who choose not to continue additional physics courses beyond the intro level (such as those of us who were also science majors but not physics majors). I'm often disappointed to learn that other universities only offer an algebra-based physics course to non-physics majors. That was not the case when I was in college; the bio and chem majors all needed to take a calc-based physics course. There's no reason for them not to be able to handle the types of problems presented in a calc-based intro physics course, and in my opinion, knowing how to derive the formulae really helps solidify understanding of what they mean and how to use them. The algebra-based physics courses were for non-science majors when I was in school.

    For those who will continue on as physics majors (and the same applies for any major that starts off with an intro course), the intro course functions as somewhat of an outline of what topics are included within the subject and some basics about them so as you work on each specific area in depth in your advanced courses, you have some context of how it fits within the broader subject content.

    For as long as intro courses have been offered, students have complained they have simultaneously too much and too little content. And, that's probably correct. :biggrin: As others point out, high school backgrounds vary greatly, so in order to ensure all students are adequately prepared for the more advanced coursework, they all take these intro courses. For those with a good high school preparation, the courses may seem too easy and too slow as they are impatient to learn more. For those with weaker preparation, the course may seem difficult and overwhelming in the amount of material covered. The pace will not slow down in later classes, but the difficulty level will increase.
  26. Nov 7, 2009 #25
    "Wasn't this issue pretty much why Feynman came out with his lecture notes, because people who get excited about physics as a career end up somewhat bored by the intro stuff? I remember hearing that somewhere?"

    All I can add to this is that I believe it was Feynman who said college physics curricula are indeed taught backwards. In other words, (and I'm paraphrasing), by the time one reaches grad school, you learn (horrifically) that the prior four years of physics was all bunk. :-j
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