Recent content by Ertosthnes

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    Schools Thoughts on math education - From a young college student.

    Hey JyN - I just finished my bachelor's in math and found that my experience was very similar to yours for many of my classes. The professor would stand in front of the board and regurgitate the material in the book for the period of the class, everyone would take notes and then class would let...
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    Understanding the Wavevector: Exploring Its Role in Optics and K-Space

    Start with something that makes sense, like the fact that you have more momentum with a smaller wavelength. So basically, p=h/\lambda, where h is some constant. Since \hbar=h/2\pi, p=h/\lambda=2\pi\hbar/\lambda=\hbar k, where k=2\pi/\lambda, ie, k is just a vector in the direction of...
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    Test your focus/how fast you juggle tasks

    100 on both, I found that test very easy. On the other hand, I pretty much never multitask.
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    Point charges in non-inertial reference frames

    Okay, in inertial reference frames, two particles with the same charge will always repel each other. Even if they were moving in parallel at high speeds, and thus producing magnetic fields, special relativity would come in and balance the forces from the electric and magnetic fields so that...
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    Statement about factorials that I don't understand

    I was reading and came across this statement: If t > 2n^2 is an integer, then t! > (n^2)^(t-n^2) I'm not sure why it is true. I don't know what equations are relevant. My feeling is that you don't need anything more than algebra, but perhaps it would also follow from the gamma function...
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    Conceptual question about torque translation

    Well in this case, I don't know how to interpret the answer. I only used Mathematica in this case because I had a suspicion that I didn't know how to solve that type of differential equation, but I was curious as to what the answer might look like. If the problem had involved an equation that...
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    Conceptual question about torque translation

    Oh, I see. I guess the acceleration is non-constant because the force of the weight does not remain perpendicular to the bar? I don't think I know how to solve differential equations like dd(theta)-(rmg/I)cos(theta) = 0. I entered it into mathematica and got this...
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    Conceptual question about torque translation

    If that's all right, then to determine the difference in speeds after a given time, I think that using the equation: \theta = \omega t + (1/2) \alpha t^2 would do the trick, after substitution into w2 - w1 = {rm \sqrt{2gh}sin \theta}/I . Since the initial w is zero, and \alpha =...
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    If their was a suit that was able to stay hot on the outside of it,

    Zombie Feynman says, "Ideas are tested by experiment." However, I think it probably depends on how hot the suit is. Unless the suit was extremely hot, it would probably not have much impact on the height that you are able to dive into water without incurring injury. This is because water has...
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    Conceptual question about torque translation

    Sorry about the notation. Okay, for the first case with a weight hanging from the bar: \DeltaL = Rx\DeltaP Iw1 = rmvsin\theta =>w1 = rmvsin\theta/I For the second case with the weight that fell from a height h: \DeltaL = Rx\DeltaP \DeltaL = rm(v+\sqrt{2gh}-0)sin\theta Iw2 =...
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    Formula for the velocity of the centripetal force

    It's F = (mv^2)/r, directed radially inward.
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    Formula for the velocity of the centripetal force

    Here are the formulas you will need to solve the problem: v = rw w = 2pi/T By the way, the "velocity of a centripetal force" does not have much meaning. Force is a vector; it doesn't have velocity. You might as well have asked what the mass of the force was, or the radius of the force. I...
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    Angular frequency, phase velocity, and period

    The phase velocity isn't important. If you have angular velocity (w) then you can always find T using T = 2pi/w.
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    Conceptual question about torque translation

    Regarding my previous post, I'm thinking that the answer to my last question is that w2 = w1 + (r*mv)/I, where v = sqrt(2gh). That would mean that w(f) = (w1 + r*mv/I) + alpha*t, which would answer the question for a given period of time. The given rotation part seems messier. Basically...
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