Recent content by brollysan

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    Equations relating to a loudspeaker?

    You could also use diffraction to justify the size of the loudspeaker, the reason bass speakers are so large for instance is that for low frequencies single-slit diffraction requires a large slit for the intensity of the sound to be localized in a narrow angle-range.
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    Does Heat Energy Have Mass and Affect Gravity?

    Hi guys just something I am a bit curious about, if heat is a form of energy, doesn't it follow from the mass-energy equivalence that heat energy has mass, however small? Then does this mean that heat energy has gravity/can be affected by gravity? I am curious about energy in general but heat...
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    Thermal physics (Gibbs free energy mostly)

    For the second part, the integration becomes an integral of temperature. You will get dS = Cp 1/T dt. And yes it is an integration constant, we are operating at constant pressure but different temperatures, so it must have an entropy at its initial temperature Ti: S(Ti,P) The final enthropy is...
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    How Does Phase Angle Affect Current in an Undriven RLC Circuit?

    Well With T = 2L/R and W = sqrt [(R/2L)^2 - 1/LC] Since q(t) = Q0exp(-t/T)cos(wt + Ø), and q(0) = 1 then => a: 1 = Q0cos(Ø) then dq/dt = I(t) and I(t=0) = 0 => b: dq/dt = Q0[(-1/T)*exp(-t/T)*cos(wt +Ø) - wexp(-t/T)sin(wt +Ø)] which implies: 0 = (-1/T)*cos(Ø) - w*sin(Ø) => Ø = atan(-1/wT)...
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    Thermal physics (Gibbs free energy mostly)

    You must take the same class as me haha! The first part I cannot help with as I barely know latex and I need partial derivatives, just know that if S= S(a,b) then dS = partial S with a at constant b + partial s with b at constant a For the second part, since you are using Cp you are operating...
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    How Does Phase Angle Affect Current in an Undriven RLC Circuit?

    Homework Statement I am given a RLC circuit in series with a fully charged C. There is no applied voltage at this part of the problem. Using kirchhoff I arrive at a second order diff.eq which leads me to the (correct) solution for the charge in the capacitor: q(t) = Q0exp(-t/T)cos(wt + Ø)...
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    Converting Complex Exponential Functions to Trigonometric Functions

    Ah yes thank you it all makes sense, I used that formula for the sum of an angle because the book insists that the following are equivalent, which does not agree with the formula for the cosine of sum of angles. (1) Z(t) = Acos(wt +ø) (2) Z(t) = Asin(wt)cos(ø) + Acos(wt)sin(ø) (3) Z(t) =...
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    Converting Complex Exponential Functions to Trigonometric Functions

    Actually plotting the function let's me "see" by how much it is out of phase so numerically I can approximate the Cos(wt + ø) but analytically? (There is an answer, so says the book) How do you find the amplitude of 2 signals being added? -5.8cos(wt) -2.2sin(wt) Still not able to find the phase.
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    Converting Complex Exponential Functions to Trigonometric Functions

    But (-5.8 + 2.2i)exp(iwt) = (-5.8 + 2.2i)(cos(wt) + isin(wt) = -5.8cos(wt) -5.8isin(wt) +2.2icos(wt) + 2.2(i*i)sin(wt) = (-5.8cos(wt) -2.2sin(wt)) + i(2.2cos(wt) -5.8sin(wt)) Where the first part is the real part, leaving me with both a sine and cosine and unfortunantly not a sum of cosine ;(
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    Converting Complex Exponential Functions to Trigonometric Functions

    "Reduce" a trig.function Homework Statement Z(t) = the real part of : (-5.8 + 2.2i)exp(iwt) 1. Reform it into: Acos(wt + ø) 2. Then reform it into Bsin(wt)+Dcos(wt) Homework Equations The Attempt at a Solution I found the 2nd step to be much easier as I just have to...
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    Integrating a function in infinite space / sphere

    Homework Statement Integrate exp(-3(sqrt(x**2 + z**2 + y**2))) over infinite space [-inf, inf] on xyz Well transforming to spherical coordinates leaves me with the equation at 3.attempts at a..() but here is my problem, how can you equate an integral over an infinite space to a spherical...
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    General solution to a simple ODE

    Whenever I am stuck I usually manage by sitting down and working on the problem and eventuall finding the solution, this one is bothering me too much and I don't have any class until friday so no hope of finding out before then unless I ask here. Q: Find a general solution to the diff.eq...
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    Final Clarification: Collisions in Special Relativity

    Wonderful, this make a lot of sense. I just have another question. In the frame of A, if A observes the duration of the movement of B from x = 0 to x = 100 to be 5 seconds then B will in his own frame observe it to be 5*(sqrt(1-v**2))? But in Bs frame of reference he is at rest and A is...
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    Final Clarification: Collisions in Special Relativity

    So they must share the same starting position to be able to agree on t = 0? Why won't they agree? I am familiar with the famous train thought experiment but the same thing that confused me there leads me to these questions I posted here. In the train experiment both observers are right in their...
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