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Is physics just not for me?

  1. Nov 24, 2011 #1
    Ever since my first midterm, I've been studying hard with a friend and drilling through very difficult problems almost everyday and throughout the weekends. I think this time, I did much worse. Admittedly, there was one or two chapters I was weak in, but I thought I felt well prepared for the exam, and yet I still did terrible. I put in half the work for linear algebra and calculus, and I'm doing better in those two classes. Is physics just not for me? Should I just stick with math instead?

    I did enjoy spending my free time doing practice problems on the weekends, but it is quite discouraging and depressing when you try so hard and yet do terrible on the exams.
  2. jcsd
  3. Nov 24, 2011 #2
    which physics?
  4. Nov 24, 2011 #3
    Are you asking which physics I am interested in or what I am currently taking right now?
  5. Nov 24, 2011 #4
    He means which physics are you having trouble with?

    Retribution, stick it out. I've been there actually. Now I can't believe that I had trouble with physics and find it very easy actually. It just kind of clicked with me one day. Its hard to describe how actually.. part of it was something like this:

    I started treating all the equations similar to what I seen in Linear Algebra. A spark went through me when I saw gauss' method. I realized that the best way to do physics is to think of it as purely equation manipulation. I would just keep manipulating equations around, just for the heck of it, take it here, put it there, take this out, put this in, whatever it is! Just play with it! I can't explain it, it just kind of clicked with me the past 2 weeks!

    Beforehand, I kept thinking about everything too conceptually. It didn't take me anywhere without knowing how to manipulate equations and ideas around.
  6. Nov 24, 2011 #5
    High five to Nano-Passion on that one :-)

    There's a quote attributed to Paul Dirac on the exact same note:

    A great deal of my work is just playing with equations and seeing what they give.
    --Paul Dirac
  7. Nov 24, 2011 #6
    Haha.. that is quite weird because I was thinking the same thing earlier today in the figment of my imagination of being a physicist. Amazing quote!
  8. Nov 25, 2011 #7


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    Staff: Mentor

    Hint: Don't expect people to remember (or have seen) your situation from previous threads that you've posted in.

    If you're in the first semester of introductory physics, it may be too early to come to a conclusion about what you want to do with the rest of your life. IMO, you should consider your difficulties as a "wake-up call" and see if you can improve during the second semester.
  9. Nov 25, 2011 #8
    Well it is mostly mechanics. I'm not even doing "real physics" yet, and I'm already struggling. How do I expect to do well in upper year classes if I can't even handle the baby stuff?

    As for linear algebra, well I've never worked a problem where you have more variables than independent equations, and thus parameters, so I can't really see any parallel. But, it's not really the math that is giving me the problem or rearranging for variables, I actually find that to be quite trivial and to be the easiest part of solving the problem. I don't know how helpful doing an exercise in notation will truly be to me in becoming better at physics, even though it worked very well for you.

    I think for me, my main problem is lacking in physical intuition and mostly the conceptual aspect of the problems rather than the computational part.
  10. Nov 25, 2011 #9
    Well not the computational part, but I guess it would be more accurate to say the conceptual aspect of the computation clicked. lol

    Anyhow, what problems are you having with physics? What concepts don't you get? If you post them then people can help you out.
    Last edited: Nov 25, 2011
  11. Nov 25, 2011 #10
    I'm curious, do you feel confused about the material before the test, and then not surprisingly you bomb the test? Or do you feel comfortable with the material before the test, comfortable with the questions while taking the test, and then are just shocked when a bad grade hits?

    Because of it's the latter then maybe you just need to work on test taking skills, which is a complete different thing.
  12. Nov 25, 2011 #11
    Retribution, don't be discouraged. As you do the problems try to get as much intuition as possible. Make sure you get every problem right, and whatever you don't get right then take note of your mistake and what intuition, misplaced or wrong, led you astray. Write it down if you have to! You will get there, it is too early to doubt too much.
  13. Nov 25, 2011 #12
    "Physical intuition" is trivial. It comes to you if you work enough derivation or practice problems. If you're focusing on pure visualization, you're going to get lost. Plus, it's somewhat useless. Why would you ever have to visualize certain things (such as potential energy) anyway? Let math lead the way. Sometimes, physics is counter-intuitive.

    This too; Victor is spot on. Many of the physics professors make the problems intentionally difficult because physicists enjoy challenging problems, and they want to see how well they taught their students how to reason rather than memorize equations to use (which they usually provide on the exam anyways).

    Wouldn't you be bummed if you had a really easy exam? Wouldn't it seem like a waste of time and a chore to just perform the calculations that computers can do on their own via plug-and-chug? If you're getting a bad score, but comparatively, you're doing okay, then don't worry about "doing poorly".

    If you're actually doing poorly, that's a different story. I would question where you got such confidence that you can do the practice problems fine. How long does it take you to do the practice problems? Doing them on a timed exam is different from slowly figuring things out.
    Last edited: Nov 25, 2011
  14. Nov 25, 2011 #13
    I politely disagree. Visualizing the potential energy field is definitely a useful thing.

    In 1 dimensional cases, such as earth-gravity, visualizing the PE field can help you get a feel for how high up a thrown object can go, and why.

    And much more interestingly, in 2 and 3 dimensional cases like generalized gravity or electrostatics visualizing the PE field give you feel for where a particle is likely to move, and how fast, seeing as how particles tend to seek out numerically lower potential energies; also if the potential energy field is non-moving then being able to visualize it will help you get comfortable with the idea that the particle simply cannot enter certain pockets of space with numerically high PE values due to lack of kinetic energy (which is sort of like the "how high can you go" idea, but in multiple dimensions).

    I politely disagree again, at least specifically in the case of mechanics and the sort of calculus associated with mechanics I think everything can be pretty intuitive :-)
  15. Nov 25, 2011 #14
    Not to deviate too far from the topic, but if by visualization of earth-gravity, you mean assigning values at various heights using the equation

    1/2 mv2 = mgh

    there isn't an absolute reference frame from which you can define the height. (Also, the error term grows larger as the height increases, but that's another problem entirely.) I guess if you really wanted to visualize the potential field from the point of view of throwing a rock, you can define the zero height from yourself. For your multiple dimension visualization, the potential energy is always lower in the direction in which the attractive force is greatest (and the repulsive force is weakest). You can view equipotential surfaces if you want to, but I really don't know how you can claim that imagining a visual picture adds to your understanding.

    What do you do when, say, you want to visualize how an electron moves around a nucleus? Okay, actually, that isn't mechanics, so I'll give a question relevant to the context of mechanics. How do you visualize chaotic motion, such as that of a double pendulum? The Earth is rotating about its axis. Therefore, the Earth bulges outward at the equator. Suppose the Earth is a giant slippery block of ice. If I were standing at the equator with no initial velocity, which way would I slide?

    I'm not saying that visualization is a bad thing, but sometimes it is unnecessary and misleading, and trying to visualize literally everything leads right into certain traps and pitfalls. Visualization is a qualitative thing, and physics aims to be as qualitative as possible.
    Last edited: Nov 25, 2011
  16. Nov 25, 2011 #15
    Ok, sure, visualization doesn't add to understanding. So in that case let's take all of a school's physics students and surgically remove the parts of their brains that deal with visual-spatial reasoning (since it doesn't really add to their understanding of physics anyway). Then let's come back 50 years later and see if any of them have successfully done any interesting research.
  17. Nov 25, 2011 #16
    That you would suggest something so preposterous is beyond words.

    Go troll someone else.
  18. Nov 25, 2011 #17
    Do you still claim that imagining a visual picture does not add to your understanding on matters of physics like equipotential surfaces?
  19. Nov 25, 2011 #18
    Does it matter? Stop derailing the thread.
  20. Nov 25, 2011 #19
    Does it matter? Seriously? Yes, it does matter that the community expresses to troubled students that visualizations always matter in first year physics, because they do.

    The original poster just said that he thinks his problem is with a lack of physical intuition. And then you go and tell him that visualizations are not really that important, but if he wants to acquire this not-so-important skill anyway then he should just drill more problems and it'll magically come to him after enough blood, sweat, and tears.

    No, you're completely wrong. He needs to stop punching numbers into his calculator and just sit staring at the pictures for a while so that he can learn what the core equations actually mean beyond just being a collection of symbols on paper.

    You stop derailing the thread.
  21. Nov 25, 2011 #20
    This is right imo, the first thing I learned in solving physics problems was to 1) write down everything I know: variables, relevant equations; and then 2) draw a picture to help visualize the problem and see how to apply things.
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