Recent content by Chronos000

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    How Do Pions Relate to the Strong Force?

    Homework Statement I'm not sure how pions relate to the strong force. My notes say that only gluons propagate the strong force between quarks - holding a neutron together, and that residual force (I imagine between the quarks of neutrons and protons) holds neutrons and protons together in...
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    Understanding the Dex Error System in Black Hole Mass Measurements

    Homework Statement I've been reading various journal articles about black hole masses. The values given there are given by X +/- Y dex. I cannot find any literature on "dex" nor do the articles go into detail as it is evidently a basic concept that I've just never come across. Could...
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    How Can Galaxy Mass Be Estimated from K-Band Luminosity?

    Homework Statement I'm trying to understand how the mass of a galaxy at redshift 1 can be estimated by knowing its luminosity in the K-band. I've been told you are able to use the IMF but I'm not sure of the details. I really don't see how you could use the salpeter, or the luminosity...
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    Quantum mechanics, symmetry and degeneracy

    Homework Statement I'm struggling to understand the concept of symmetry in quantum mechanics. My notes state "In general if the probability density has lower symmetry than the hamiltonian, the wavefunction will be degenerate". I don't really get the connection with the hamiltonian. It...
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    Calculating Star Visibility: RA and DEC at 09:30 on May 21st

    Homework Statement If at 09:30 21st may what would the RA of stars be at the zenith? I'm not sure if we can say that they are at 3.5hrs since we are in may? If a star is at RA 5hrs would at 09:30 would it be observable at 00:00. My thoughts are that you just add on 14.5 hrs to the...
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    Joule kelvin expansion, thermodynamics

    I think I may have confused a jk expansion with a free expansion of gas where the gas is confined in volume V then is allowed to expand into a vacuum. could you please explain further about this "flow energy"? and for an ideal gas, I don't see how change in T =0 if there is a change in P and V
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    Joule kelvin expansion, thermodynamics

    Homework Statement for a jk expansion, I know dU=0. I think this is because dQ=0 as its isolated and dW = 0 as there is no work done against the surroundings. but is dW 0? does the gas do work against itself? I have also seen that the temperature change of an ideal gas = 0. how can...
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    Reversible process/entropy thermodynamics

    Homework Statement For a reversible process, while the net entropy change must be zero, does this mean that the entropy of the system and surroundings can change as long as they amount to zero?
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    Thermodynamics proving cp/cv = kt/ks

    Homework Statement at some point in my derivation I get to the following line: cp/cv = (dS/dP)T(dP/dT)S / (dS/dV)T(dV/dT)S I think this equals (dS/dP)T(dS/dV)P / (dP/dT)V(dV/dT)S - from applying maxwells relations. but my book says it is in fact the following: (dS/dP)T(dV/dS)T /...
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    Thermodynamics, confused with definitions

    my notes have further manipulated this term though, which does't seem right if its zero
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    Thermodynamics, confused with definitions

    dV means change of volume, no change, dV = 0
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    Thermodynamics, confused with definitions

    it is zero right?
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    Thermodynamics, confused with definitions

    Homework Statement dU = dQ + dW so dU = Cv dT... but only if dW is zero right? as dQ = CvdT so then the central equation is TdS = dU + PdV which is then TdS = CvdT + PdV according to my notes. surely PdV should be zero no?
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    Quantum, finding energy eigenvalue spectrum

    I got it eventually thanks
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    Quantum, finding energy eigenvalue spectrum

    is (λ/k)^2 just subtracted from the energy of the ground state?