Recent content by jdougherty

I am making it more complicated than it needs to be, but that's intentional. In coordinates the problem is relatively easy, but I'm interested in whether it can be done without introducing the coordinate vectors on top of the Killing vectors already provided. I have another question about the...

Homework Statement Show that a static, spherically symmetric Maxwell tensor has a vanishing magnetic field. Homework Equations Consider a static, spherically-symmetric metric g_{ab}. There are four Killing vector fields: a timelike \xi^{a} satisfying \xi_{[a}\nabla_{b}\xi_{c]} = 0 and...

When x = 1, you have 1 = A(1-1^{4})+B = A(0)+B = B So B = 1 works, but what values of A satisfy that equation? What values don't? If there are multiple values A can have, then you need to determine which is the correct one.

One way to think of it is the following: If we could find the antiderivative by "normal" means, then we would get \int \frac{1}{x}~dx = x^{0} = \textrm{constant} which is clearly not true from looking at the graph of 1/x Another way to look at it: the reason we can do the reverse power rule...

Your integral is close. The function y represents the radius of some circular cross-section, so the integral to maximize is \int^{a}_{0}\pi \left(y(x)\right)^{2}~\textrm{d}x With this integral, you should be able to use your relevant equation, though keep in mind that the total length of y is...

Hi Aicelle, welcome to PF! You're right so far, d_{2} = \frac{15 d_{1}}{20}. But you have one equation now, and two unknowns (d_{1} \textrm{ and }d_{2}). Can you think of another relationship between them? How do they relate to the total distance?

Oh, physics girl phd makes a good point. My school doesn't have a PDE class for physics majors (we're expected to just pick it up along the way, I guess), but if you have access to a class on Diff. Eq's then I would second that recommendation.

From my friend: "do take complex analysis before quantum. It's an easy A for someone who's good at math and physics. If you are getting or have gotten an A in Mechanics 1, it may be ok to take quantum 1, EM 1 and mechanics 2, but don't take any 4th course that may be demanding in any way at the...

My friend is a physics major at UIUC, so I'll ask him about the particular courses you guys have. As for complex analysis, I wouldn't recommend taking it unless you want to. In 20 weeks of quantum I encountered complex analysis once, in doing a particular integral. If you're interested, by...

The feedback you got should give you a clue as to what the relevant equations are. Do you know of some equations which relate kinetic energy to velocity and power to energy?

I'm not entirely sure what the analogue of the above reasoning would be, but it seems to me that it would involve rotation through a 4th spatial dimension, which I have a difficult time imagining. Also, I'm not entirely sure I understand your visualization of the R^2 situation anyway. This...

Spin is a little bit tricky, and a course in QM usually involves a lecture or two about the addition of spin. A deuteron is made up of two spin-1/2 particles, so it can have a spin of 0 or 1, where a spin-0 state is when the spin number and the magnetic number are both 0 for both particles...

Hey everyone, I'm rather new as well, but I joined PF for this sort of thing, so I'm all for it. This week I'll be completing the coursework for an undergrad physics degree (we're on quarters), and I've spent a lot of time doing independent math study as well. I'd be up for anything...

This is, in fact, the correct way to do it, easy though it may seem.

The error function is defined as \textrm{erf}(x) = \frac{2}{\sqrt{\pi}}\int^{x}_{0} e^{-t^{2}}~\textrm{d}t and pops up a lot when one does integrals with exponentials, even though it doesn't always imply that there is some sort of "error" involved. cf...