Recent content by golanor

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    A Expanding CCRs, and their underlying meaning

    Yes, I think it is Wightman QFT.
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    A Expanding CCRs, and their underlying meaning

    Thanks for the reference. I skimmed over it, seems interesting, but it is definitely not what I was talking about. Not at all what I meant.I tried to look up what I was talking about - apparently the idea was to "smear" the annihilation/creation operators, which modifies the CCR. Another place...
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    A Expanding CCRs, and their underlying meaning

    Hi, I remember seeing a few months ago, at a lecture about statistical signal processing, something which looked similar to commutation relations, only with a gaussian, instead of a delta function. Basically, it looked like this: $$\left[\phi(x),\phi(y)\right] = ie^{-\alpha(x-y)^2}$$ This...
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    Comparing Work Output in 200K/300K and 300K/200K Environments

    Sorry, guess I was kind of lazy with copying it. a) \int_{200}^{300} {\frac{300 - T}{300}}{dT} = 100 - 250/3 = 16.67 b) \int_{300}^{200} {\frac{T - 200}{T}}{dT} = -100 + 200 * \log(3/2) = 19
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    Comparing Work Output in 200K/300K and 300K/200K Environments

    Homework Statement We have two different set ups: a) A 200K brick in a 300K environment b) A 300K brick in a 200K environment From which one of these can you extract more work? Assume equal mass and heat capacity. Homework Equations Efficiency - η=\frac{T_H - T_L}{T_H} and: W = ΔQ => W≤ Q_H *...
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    Taylor Expansion of Natural Logarithm

    The remainder must approach 0 for every c between x and 100. If i can find even 1 such number for which the remainder does not approach 0, it means that the series is not a correct estimation for the function.
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    Taylor Expansion of Natural Logarithm

    It's very confusing. If the Lagrange remainder doesn't approach 0 it means you cannot estimate the function correctly, but in this case the calculation of the series does give accurate estimations. It's very interesting. Does anyone know the answer to this?
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    Solve Rotational Dynamics Homework: Hollow Cylinder, Weight, String

    The point I missed was the relation between the cylinder's acceleration and the weight's acceleration.
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    Taylor Expansion of Natural Logarithm

    yes, but since c is between x and 100, if x is bigger than 50 or smaller than 200 it won't diverge for any x and for any c. when i pick x=1, for example, for 1<c<99 the limit diverges. you cannot talk about a series in that case, because the remainder does not necessarily converge to 0.
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    Taylor Expansion of Natural Logarithm

    That's why it is undetermined and not infinity. x=50 is the smallest x for which the limit will always be 0. anything lower than 50, and the nominator could be larger than the denominator => the limit will diverge.
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    Taylor Expansion of Natural Logarithm

    That's the thing. \lim_{n\to \infty } \frac{(x-100)^n}{c^{n+1}*(n+1)} goes to 0 only for x≥50. x≤c≤100 for x<50 it cannot be determined.
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    Taylor Expansion of Natural Logarithm

    I just realized something - can we even talk about a taylor series in this case? The Lagrangian remainder doesn't approach 0 as x approaches 0 (or even 1). The interval in which the remainder approaches 0 is (50,200), and not (0,200).
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    Solve Rotational Dynamics Homework: Hollow Cylinder, Weight, String

    They have the same density. I=\rho \left(\int _0^h\int _0^{2\pi }\int _0^Rr^3drd\phi dz+\int _0^h\int _0^{2\pi }\int _0^rr^3drd\phi dz\right)=\frac{M}{\pi *h\left(R^2-r^2\right)}h*\frac{\pi }{2}\left(R^4-r^4\right)=\frac{M}{2}\left(R^2+r^2\right)
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    Solve Rotational Dynamics Homework: Hollow Cylinder, Weight, String

    Well, i forgot the 1/2 there. it's basically the MI of the large cylinder minus the one we took out. They are co-centric so there is no distance to add. if i look at extreme cases - r<<R it's as if the cylinder is complete, r=R - there is no mass. = the equation makes sense...
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    Solve Rotational Dynamics Homework: Hollow Cylinder, Weight, String

    I understand..just got confused by something we proved in class. So, the linear acceleration should be: \sum F=T-f=M*a_1 and the torque around the center of mass: \sum \tau =R(T+f)=\text{I$\alpha $} Around the point of contact: \sum \tau =2R*T=\text{I$\alpha $} And in this case, the moment...
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