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Why is intro physics difficult for me?

  1. Dec 14, 2012 #1
    By intro physics I mean calculus based Physics I (Newtonian physics).

    I'm a freshman planning on majoring in CS and this is my first semester in college. I'm doing well in all my other courses, all A's (calc, intro to CS, others)... but physics, man.

    I'm not kidding when I say, with a 5 course course load, I spend probably 50% of my study time studying for physics, and I STILL only pull off an average of 10/15 on tests (66%). The average for the class is usually 8/15 (so failing) but for me this grade is unacceptable. I'm used to getting good grades in high school, but in college is the average being failure a relatively common occurrence in the hard sciences and engineering courses?

    I have to spend all my time studying for a course not even related to my major (for the most part anyway). Don't get me wrong, I enjoy physics problem solving and appreciate the creativity involved in coming up with solutions to some of the problems, but man!

    Did anyone else feel the same about their first physics course? Be honest even if it must be blunt!

    (Also should mention I did not take physics in high school).
  2. jcsd
  3. Dec 14, 2012 #2


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    Not taking it in HS would make it more difficult.

    You need to review the problems you had trouble with and identify exactly where you went wrong. Sometimes it's a key concept, sometimes it's your common sense interfering with the physics.

    How is your math? Are they using Calculus in the class?

    Are you getting lost in the variety of formulas and when to use them?
  4. Dec 14, 2012 #3
    Introductory physics tends to be a weed out course in most universities. It is a common occurrence.
  5. Dec 14, 2012 #4
    Thanks for the advice.

    My math is decent I suppose. I'm getting an A in honors calc I anyway (only difference from reg is that the course places more emphasis on theory and proofs), but the calculus/math isn't really the difficult part of physics for me; it's the large amount of conceptual information thrown at us at once, most of which is brand new to me, so it's a lot to remember. In class we fly through so many topics that I barely have time to "soak in" what the professor is saying, so I feel like most of my time learning is by myself studying...
  6. Dec 14, 2012 #5


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  7. Dec 15, 2012 #6


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    Not just difficult for you, but also for many other students. Whether physics done before in high school, or some simple "elementary" physics course before in college - no matter - those are not adequate preparation for your Physics 1 Mechanics course. Those simpler ones expect you mostly to solve problems by plugging values into formulas. Now, you must understand concepts, analyze problem descriptions, choose the relevant formulas, and use and TRUST your Algebra and basic Trigonometry.

    For studying, read the book sections, FIVE OR SIX TIMES if necessary and really dig into the textbook discussion very carefully.
  8. Dec 15, 2012 #7
    The first exposure to physics is difficult for most people. I think the reason why is that the way math is used is unfamiliar: while you learned it all in math class, you usually stick to one technique at a time. Solving physics problems requires combining techniques from random parts of your math background, for example solving simultaneous equations where one is the derivative of the other, and I think people aren't used to doing math like that. (In my Calc class, algebra was rarely used to solve problems, and in my algebra class Calc was never mentioned. In physics these two subjects are almost always used together)

    Aside from just using math techniques like that, physics concepts are used like that too. Some solutions will use conservation of energy in the first line to relate two quantities, and others never refer to conservation laws. Having physics knowledge is like having a tool box. You have to be familiar with what's in that tool box, and what each tool is useful for. So essentially, many other classes teach how to use tools, but physics teaches how to use a tool box. If you try to reduce the concepts you are being tought to the tools you are using (and recognize that a lot of things are applications of tools and not new concepts), you may find things easier to follow. In my experience students just aren't used to having to consider so many options for solving problems, and I think that's what trips people up.

    I should also mention that I struggled with my first year physics course, and I was in the non honors section. But by my fourth year I got straight A's in QFT, a 2nd year grad course. If you hadn't seen physics before, like I hadn't, freshman physics is going to be difficult. Just keep at it, and remember that 100% of physics is about using and improving that tool box, nothing else.
    Last edited: Dec 15, 2012
  9. Dec 15, 2012 #8
    Physics is tough for darn near everyone, no way around it. You will probably struggle, it's completely normal.
  10. Dec 15, 2012 #9
    For what it's worth, seeing a class average of around 50% in a first year physics course doesn't surprise me at all. Your first fight with university-level physics is usually a tough one.
  11. Dec 15, 2012 #10
    I took my intro physics courses concurrently with calculus (without high school it was my first exposure to physics and calculus). I found it difficult. More difficult than many (or most) of my upper division coursework. The unfamiliarity was a killer.
  12. Dec 15, 2012 #11
    This is what I tell new students who hire me to tutor them:

    1) In calc-based physics, they will do a lot of calc derivations in lecture, but the exams don't often have that much calc on them. So your HW and notes studying may not translate to doing well on the exams. Buy any old non-calc text off amazon (should be less than $10, usually called "College Physics") and practice the chapter problems from the same section as your calc text. This should really improve your test scores (or else get Schaum's book of 3000 solved problems and really dive in). You are probably heading into E&M next semester (hopefully). This will be even more important to do then.

    2) Solving physics problems is like waking up and finding that you have been buried alive. You are in the dark, clawing and scratching for some way to get out. This "panic sensation" never changes (we physicists get addicted to the rush), and you need to learn to train your brain to operate "in the dark". So EVERY time you attempt a new problem, don't cheat by looking in the text or notes or anything. Force your brain to attempt the problem for several minutes on its own; feel the burn. Then when you can't get it, look up how to do it, but you will slowly be whipping your brain into physics shape.

    My new tutees tend to do much better after I make them understand that in physics you never know how to do the problem ahead of time, that you are supposed to feel that panic and use the intensity to boost your brain to think faster. Until they understand this, they think that there is something wrong with themselves for not knowing how to do the problems. But it takes a lot of practice. Work with others when doing homeworks (to be efficient), but study alone before the test. I used to work on the whiteboard of an empty classroom the night before each exam, forcing my brain to do problems without looking at the solution (well, until I was stuck for too long).

    Good luck!
  13. Dec 15, 2012 #12


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    Welcome to learning physics.
  14. Dec 15, 2012 #13

    This is a bit grim for my personal taste... but it's exactly what I was trying to say. Each problem you are starting *almost* from scratch. All you have are things you know to be true, and past experience applying them. Students just starting physics have neither.

    So instead of thinking "I've never done a problem where a block is sliding down a wedge before" think "I've done classical mechanics problems before, this is no different".
  15. Dec 15, 2012 #14


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    Is 8/15 really considered failing? What's the grading scale being used? You should rid yourself of the notion that 90%-100% means an A, 80%-90% means a B, etc. That's a pretty arbitrary scale that may or may not apply to your class. The relevant scale really depends on how the instructor wrote the exam.

    Exams should contain problems of varying difficulty to properly assess how a student is doing. There should be easy stuff almost everyone should have mastered, and there should be difficult stuff only a few will get. If you get a bunch of people scoring 90% to 100%, it likely means the exam was too easy.

    It's common. Some people just get it. Others have to work really hard at it. No one really knows why.

    One of the major difficulties with people learning physics is that they come into class with preconceptions about how the universe works. You have to unlearn those first otherwise it's hard to incorporate the new concepts. For example, most people think that for something to move, there has to be something pushing or pulling it. That makes sense from everyday experience, but it directly contradicts Newton's first law.

    You also have to keep in mind that college isn't high school. It's definitely faster paced, which you will get used to. What's more important is that you're expected to take responsibility for your learning. Your class is probably large, and the instructor simply doesn't have the time to hand-hold struggling students. If you're having difficulty, you should seek help. Go to office hours for your professor and TAs. Work on homework with others instead of trying to go at it on your own. Don't flounder and delay until it's too late.
  16. Dec 15, 2012 #15
    The thing about Newtonian mechanics is that it's skill base really requires you to intuitively think about the physical situation of the subject. It's one thing to be able to do all the math, which I believe you are capable of since you are getting an A in calc. But as far the actual problems go, it is very difficult at first to look at a problem and get the initial equations from the particular problem. So here's what you: 1) Do a lot of problems, and more importantly, look at the answers and see if you have them right.
    2) An easier rout, but still a lot of effort, is to get a book or some source that provides a lot of examples on the topic. That way you can try out the problem without looking at the solution, and then analyze how you did things wrong. I promise you that the more problems you do, the easier that subject gets.

    So the way I'd approach this is try to understand how to represent motion in cartesian and polar coordinates first. Try some problems to make sure you have a feel of them (don't have to perfect).

    Then move to working on forces. Try out simple problems, and make sure you understand very basic systems that involve Normal Forces, Tension Forces from massless ropes, and then massless Pulley systems.

    Once you understand those basic situations, start working on more complicated systems like double pulley systems and heavy strings etc, friciton systems, etc.

    And if they have other systems like spring systems and so on, do the same thing. Start simple, make sure you understand the physics, and then move on. I know there's a lot typed out here, but it's a weeks plan tops. Give it a week of solid 4 hour practicing a day with baby steps and I garauntee you that you will get it.

  17. Dec 16, 2012 #16
    I really appreciate all the advice guys and I will definitely be applying it, thank you.
  18. Dec 17, 2012 #17


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    Hi physicsernaw,

    Disclaimer: I am neither a physics major nor an expert in solving physics problems. The following information is based on my experience in an introductory physics course, and what I found worked for me.

    I didn't take physics in high school either. I went to an extremely small school that didn't have qualified faculty in the subject, and I worked in the evenings, so a community college course wasn't an option. I think it would've definitely helped to have had exposure to it beforehand.

    That said, the most time-consuming part for me was synthesizing the concepts that were introduced. Most of the problems I was given in my introductory physics course contained implicit information that was necessary to solve/setup the problem correctly. This required an understanding of the concepts and their physical implications within a system, not just the mathematical methods involved in obtaining the solution (that's the easy part!).

    A simple (albeit handy-wavy) example: when studying the doppler effect, a problem might give you the frequencies heard by the observer, and you must infer whether the source is approaching/receding based on the change in frequency. The problem won't always tell you, "The train is moving away from/towards the observer," so you must understand the physical implications of a decreasing or increasing frequency in order to model the system correctly.

    No amount of formula or method memorization will help you solve these types of problems. They'll get you through the trivial plug-and-chug problems, but those don't really test your understanding of the physics involved, in my opinion. Your time is better spent working problems that require a synthesis of physical laws and concepts. Should you internalize methods and formulas? Of course! However, don't stop there. The "real physics" starts when you're able to "see" the physics implicitly given in a problem, and then reason your way to a solution.
  19. Dec 17, 2012 #18
    Are you doing a lot of physics problems in your study time? I find that doing a lot of problems really helps.
  20. Dec 18, 2012 #19
    OP: Dude, welcome to the club.

    As a CS major myself, calc-based physics 1 was the toughest academic ordeal I've endured to date. It forced me to completely change my study habits - no longer were rote memorization and mindless plug-and-chug repetition sufficient for doing well in that class; I actually had to understand on a conceptual level. I was stuck on a mid-high B the entire semester, and felt like the biggest idiot every time I stepped into office hours with yet another "I'm sorry Dr. _____, but I have no idea how to start this problem" question. I genuinely felt bad having to constantly pester my professor with my idiocy, but he was definitely a patient, patient guy.

    By the grace of the gods (and literally hours and hours of reading and doing practice problems), I managed to pull off an A, by the skin of my teeth. The amount of time I put into studying for physics 1 dwarfed that of my time even in calculus 2. The sad thing is, not long after I'd taken the course, the university I plan on transferring to revised their requirements, and no longer wanted the physics series. Given that I'd already taken a different physical science course in the past, that semester of mental anguish was unnecessary. Haha...but in the grand scheme of things, it was definitely a worthwhile experience.

    Seriously, just read the material and do practice problems until you're blue in the face, and ask your professor questions until he's had enough and tells you to go away. It's just one of those courses where you can't brute force through it. Good luck!
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