Recent content by Confundo

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    Solving Chain Rule A(r,t) Problem

    Problem Use the chain rule to proof \dot{A}=\partial_t A+v_j\partial_jA_i Attempt at Solution \dot{A}=\frac{dA_i}{dt} = \partial_t A_i+\frac{dr_i}{dt}\frac{\partial A_i}{\partial r_i} Obviously v_j = \frac{dr_j}{dt} I'm puzzled where the v_j and partial d_j come in
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    Commutator and hermitian operator problem

    Any good sources on operators and kets? Tends to be a bit disparate in the QM books I've seen.
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    Calculating Jupiter's Mass from Log10(a) vs Log10(P) Graph

    You can neglect the masses of the satellites I think, since Jupiter is so much more massive than its satellites. Remember that the gradient is just effectivelylog_{10}(a) / log_{10}(p) . Start by rearranging the kepler equation so you can the gradient part on one side, then take the log...
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    What are the final pressure for the gas?

    You could also use the equation involving P, T and gamma. Using the ideal gas equation afterwards is a good check though.
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    What are the final pressure for the gas?

    Use the ideal gas equation to find V_1
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    What are the final pressure for the gas?

    Just use the ideal gas equation again. You've know V_2 = 2V_1
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    What are the final pressure for the gas?

    http://en.wikipedia.org/wiki/Adiabatic_process
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    Solved: Paraxial Wave Equation - Constant Phase Surfaces

    Shouldn't of said long without a reference if I'm studying physics really :). The paraxial approximation allows the small angle approximation to be used.
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    Solved: Paraxial Wave Equation - Constant Phase Surfaces

    Thanks. Very clever piece of factorising there :). The lecturer said not to be concerned with a long equation.
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    Solved: Paraxial Wave Equation - Constant Phase Surfaces

    paraxial wave equation - Solved Homework Statement When a laser beam traveling is traveling in one direction, we can make the paraxial approximation. Question: Find an expression for the surfaces with constant phase in the beam. Homework Equations From a previous part of the...
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    Solving Wave Equation with Paraxial Approximation

    Worked that out now, must learn not to try and do derivatives in my head while tired.
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    Change in internal energy of a gas

    You can find T_1 using PV = nRT. You can then use the adiabatic equation TV^{\gamma}= constant to find T_2
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    Solving Wave Equation with Paraxial Approximation

    Oops, I see now I was looking past the obvious. I'll do the calculation in the morning. Is there a reason why they leave out the e^{ikz} from the final equation? Thanks. edit: V = V(r,z)e^{ikz} ?
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    Solving Wave Equation with Paraxial Approximation

    Homework Statement Homework Equations http://books.google.co.uk/books?id=4NXHYg70qqIC&pg=PA85&lpg=PA85&dq=paraxial+approximation+wave+equation&source=web&ots=6PbKKzSEz6&sig=bspXdKfxc-IiMV6AmoifMSJTHuk&hl=en&sa=X&oi=book_result&resnum=10&ct=result The Attempt at a Solution I...
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    Yukawa Potential Homework: Calculating Meson Energy Levels

    r is just the distance from the centre as in the coulomb potential.