Recent content by paco_uk

Thanks, I guess given the original estimates a factor of 10 isn't that bad after all.

Homework Statement This is for a class to learn about making order of magnitude estimates. I want to estimate the amount of energy released by burning a match. Googling gives an answer of about 1BTU (just over 1kJ) but I can't think how to estimate it from general knowledge. Homework...

Thanks, that's a useful thing to know. In fact, I came across their solution to this specific question today (that always seems to happen the day after I post a question here). It seems to be more of a neat trick that works here rather than being a generally applicable principal like mapping...

The equation you have given for the cross section is the Breit-Wigner formula which applies in the region of a resonance (e.g. when the centre of mass energy is just enough to create a charmonium state such as the J/Psi). I think the ratio you are being asked for is for production away from...

Homework Statement I'm trying to use the transfer matrix method in statistical mechanics but I'm struggling with the algebra so I'd like to know if there is a simpler way to find the eigenvalues and eigenvectors of a matrix. For example, studying the lattice gas model produces the transfer...

Thanks very much. I've never done a course on General Relativity so I'm pretty shaky on all this. I look forward to listening to the lectures.

Sorry about the mess. I've cleared up the latex tags. What's there now does indeed look strange to me but is what is written in the lecture notes. I don't know what the commutator bracket round the subscripts means.

Homework Statement Could someone please explain what is meant by the term: \partial_{[ \mu}F_{\nu \rho ]} Homework Equations I have come across this in the context of Maxwells equations where F^{\mu \nu} is the field strength tensor and apparently: \partial_{[ \mu}F_{\nu \rho...

Thanks for your suggestion. I think that let's me rewrite the integral as: \Gamma (s)&=&\int^{\infty}_{0} dx \, e^{(s-1) \ln{x}-x} but I still can't find a way to get it in the form required. For example, the substitution y= \ln{x} gives: \Gamma (s)&=&\int^{\infty}_{-\infty}...

Homework Statement Starting from the Gamma function: \Gamma (s) = \int^{\infty}_{0} dx \, x^{s-1} e^{-x} Make a change of variable to express it in the form: \Gamma (s) = f(s) \int^{\infty}_{0} dy \, \exp{\frac{-A(y)}{\zeta(s)}} And identify the functions f(s), A(y)...

Thank you both very much. It looks like I need to do some more reading about spin.

Thank you, I understand there is a difference between L and J and you have made it clear why the argument can't hold for J. I'm afraid I still don't understand why the argument does hold for L.

Thank you. I see what you mean that J can't be forced to obey a rule which spin doesn't obey but I still don't understand the difference between L and J which makes the original argument true for one and not the other. In fact, the more I think about it the less I understand the argument for...

Homework Statement I am trying to understand the allowed eigenvalues for the angular momentum operators J and L. In particular why, mj can take integer and half-integer values whereas ml can take only integer values. Homework Equations I have learned about angular momentum operators as...

I think you are using all the right equations but you need to be careful with minus signs. If you are regarding upwards as positive (a good idea) then your expression for y should read: Y=Y_0+V_y(0)+\frac{1}{2} a t^2 Then you can consider in which direction acceleration due to...