Recent content by Physics Enemy

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    Very Very Basic Numeracy Question - I'm Having a Dumb Moment?

    Yes you're right, it was sloppy of me. :) Thanks, I'm happy with this. So therefore: 1/10^15 = Constant * (Variation in T) Variation in T = Some Number So it's not a %, just +/- this number. Correct?
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    Very Very Basic Numeracy Question - I'm Having a Dumb Moment?

    Sorry - The k is just a constant I put in, it's actually various quantities bundled together. So the dimensions do turn out to be correct. I just wanted to simplify and focus on the Q. This is the key point and thanks for your answer. Could you perhaps expand on this? At the moment it just...
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    Show that 1/2mv^2 = 3/2kT for a star cluster

    I think he wants you to justify why they behave like particles in a gas, before you write down the equations. Perhaps Wiki it? I think you need to explain the assumptions. Hey, would you mind checking my thread? It's a basic numeracy one lol.
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    Show that 1/2mv^2 = 3/2kT for a star cluster

    But isn't the idea that they are behaving like particles in a gas?
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    Show that 1/2mv^2 = 3/2kT for a star cluster

    Isn't it something like: Assume the stars move about with a mean thermal energy, which is their KE. So KE = 1/2mv^2 = (3/2)KT Then mv^2 = 3kT => T = mv^2/3k?
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    Very Very Basic Numeracy Question - I'm Having a Dumb Moment?

    Hi, Basically the question is about doppler shift. The formula is: (f2 - f1)/f1 = -kT ; f1 = Freq in object rest frame, f2 = Freq in lab frame The Q: Often, frequencies are compared to 1 part in 10^15. In order to make use of this level of accuracy, to what extent can T fluctuate? I...
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    Absorption of Photon by a Free Electron - Impossible - Conservation Laws?

    I gave you the details. It's a conceptual Q about whether an electron can absorb a photon. Apparently it violates conservation laws. The second bit is about a centrifuge 'overcoming' this issue. Nothing else is needed.
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    Please I want a solution to this question?

    dEdT = h/2Pi dE = (6.63 x 10^-34)/(2Pi * 10^-8) J dE = [(6.63 x 10^-34)/(2Pi * 10^-8 * 1.6 x10^-19)] eV dE = 6.6 x 10^-8 eV dE = 7 x 10^-8 eV (1 Sig Fig) The energy of the first excited state is 13.6/4 = 3.4 eV, so its energy uncertainty is tiny compared in comparison.
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    Asap help please~electric fields from continuous charge distribution?

    http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elelin.html Hope that helps!
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    Absorption of Photon by a Free Electron - Impossible - Conservation Laws?

    Hey, It seems like this is impossible because momentum conservation is violated. I had a Q where an electron underwent an energy transition and emitted a photon, and then they asked whether it was possible for the photon to be reabsorbed by the electron to undergo the same transition as...
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    Equations of Motion for 'Perturbed' Or 'Oblique Incidence' Orbits?

    Hi, I've been doing a Q where particles undergo circular/near-circular motion in an electric field. The electric field varies as 1/r. With the first particle, they set it off tangentially to the field lines, so it undergoes circular motion. With the second particle, they set it off at a...
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    Lorentz Force Question - Where did the y dot come from ?

    Yes you're right. V x B = (V_y * B)xhat - (V_x * B)yhat + (0)zhat So the x component is B*ydot, and y component is -B*xdot
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    Imperial Comprehensive Paper 1 Q8 2004 - Last Part

    I've attached the paper in Q, please see Q 8. Not sure what to do. Also confused about the fact it says 'calculate', when it depends on p and delta, so I don't see why I should get a numerical value. I don't know how to get an expression for N here, apart from a really messy and horrible...
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    Lorentz Force Question - Where did the y dot come from ?

    I actually disagree with their answer, shouldn't it be -y dot? x cross z gives -y, I think ...
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