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I feel like I worry more than necessary.

  1. Jun 4, 2016 #1
    Right now, I'm thinking of a moment in my calculus-based physics class that I took last semester. Basically, the instructor is teaching us about vectors, the right-hand rule, and which direction the cross-product of two vectors is supposed to be pointing in. She assigns us homework, and I couldn't understand a word she was saying, basically. Everything was just too confusing. So I'm tasked to find out whether the cross-product of two vectors (a homework problem) is pointing in the negative or positive z-direction. I couldn't remember anything, so I just read the book and found that "the cross-product of two vectors will be perpendicular to both" or something like that. By all means, correct me if I am wrong. Anyway, I try to draw the vectors in the homework problem using a vector graph I'd printed out and figure out which direction would make the cross-product perpendicular to the two vectors. You can already tell that this was a terrible and unreliable method of determining the direction of the cross-product. I imagine that I got that problem wrong. Anyway, when she's re-lecturing us about those right-hand rules, and the vectors dictated by them, the instructor looks at the graphs I was attempting to write my solution on, and scowls at me. Right now, I can't help but worry about what she thinks of me; that I'm lazy and don't pay attention during class or even when she's trying to help me, because when I visited her in her office to inquire about this problem, she tells me to use the "right-hand rule" she described in class. I dismiss her explanations, saying that "I don't know how that works". She asks me why, and I just tell her that it's too hard. Right now, I can't help but feel shame for myself for wasting her time; and I'm worrying that she thinks of me as some lazy punk who doesn't want to work hard and listen. I feel like she hates me, even though I haven't seen her in many months... I'm not looking forward to the day that I will take her class again.
    Last edited: Jun 4, 2016
  2. jcsd
  3. Jun 4, 2016 #2


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    Gold Member

    People learn at different rates. Don't worry about what the teacher thinks of you. If you are truly interested in the subject, you can understand the concepts by many other ways like reference books, internet, video lectures, physis forums etc. Many of the important concepts in EE were clear to me only after I brought them up here on PF. You need not be solely dependent on your instructor for explanations. It's not important what she thinks of you. If you are truly interested in the subject, your aim should be to learn and not just to impress your instructor. If you excel at the fundamentals, you'll score good marks in the exam and everyone will be impressed. So if you are thinking of not taking that class just because you feel she hates you, think again.
    Last edited: Jun 4, 2016
  4. Jun 4, 2016 #3
    If your instructor has spent years teaching, I guarantee she's seen much worse.
  5. Jun 4, 2016 #4
    That's a pretty horrible attitude. And yes, if I were your instructor, I would highly dislike this attitude from you.

    First of all, before you go to office hours, you are expected to review your theory. Then anything that is unclear (like the right hand rule), you can ask during the office hours. You didn't. You didn't want to understand the right hand rule, you just wanted to get a good grade on the homework.

    Saying that "it's too hard" is no excuse. You have so many materials are your disposal: books, office hours, internet resources, tutoring. When you say "I don't know how that works", then don't expect your instructor to spoon feed your everything. You need to actively find the solution to your problems.
  6. Jun 4, 2016 #5


    Staff: Mentor

    What's so hard about the right hand rule? If you have a right hand, and some fingers on it, you can use this rule.

    A lot of people don't know their right hand from their left, so maybe that's the problem. Assuming you know which is your right hand, curl your fingers in the direction from ##\vec{u}## to ##\vec{v}## (assuming you want to find ##\vec{u} \times \vec{v}##). Now look at your thumb. It will be pointing in the direction of this cross-product.

    I agree completely.
  7. Jun 4, 2016 #6

    jim hardy

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    That's positive feedback, reinforcement of your negative feelings.
    You need to reverse something so that you'll start using your built-in positive feedback mechanism to reinforce success not failure.
    Nothing succeeds at failure like giving up.
    Nothing succeeds at success like trying again.

    Cross product is easy if you've ever used a screwdriver
    it has the direction taken by a right handed screw rotated first vector into second.

    "It's Too Hard" is an excuse. If i can do cross products anybody can.
    Quit punishing yourself. It's part of that negative mental game of laziness paid for by faux guilt : "If i just say i can't then i wont even have to try"..
    I think the shame you feel is instead for taking the lazy way out.

    Success is just a series of little daily victories. For today's work some cross products on graph paper ..
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