Recent content by SunGod87

Homework Statement Show the three components of angular momentum: L_x, L_y and L_z commute with nabla^2 and r^2 = x^2 + y^2 = z^2Homework Equations [A, B] = AB - BA For example: [L_x, \nabla^2] = L_x \nabla^2 - \nabla^2 L_x The Attempt at a Solution L_x \nabla^2 =...

Thanks a lot!

That's what I thought, but the lecturer is saying otherwise. I'm tempted to think he just misunderstood my question, since "How does d_a A^b transform under coordinate transformations" doesn't actually have a question mark after it, maybe it's just a sentance to describe the rest of the...

My question is, I can only answer "How does d_a A^b transform under coordinate transformations" after having done: "compute d'_a A'^b", right? I've also revised my solution to the second part here http://img88.imageshack.us/img88/3954/38821206vp5.jpg This is what you meant? Thanks for the...

You forgot to increase the exponent by one before dividing!

Thing is, I've asked my lecturer about this now. He says we should answer that part first? Surely he's either made a typo or he's wrong? You HAVE to do the second part to know the answer to the first, right? In fact, while I have your attention... can you check my working, please...

Sure, I've done that for the next part: "compute d'_a A'^b" and found it isn't a tensor so the partial derivative operator isn't a good operator in tensor analysis and a good operator should return a tensor. But what about the first part? I can't answer it without having attempted the next parts...

Homework Statement http://img522.imageshack.us/img522/3511/80377551yt7.jpg Homework Equations None... I think. Seems like something I should just know rather than have to work out? The Attempt at a Solution I can do everything in this problem apart from the very first part. I...

So I should have (on the RHS) -hbar/2 [c_1 | 1/2 > + c_2 | -1/2 >] When I'm done, right? Or should I have: -hbar/2 [ | 1/2 > + | -1/2 >] I'm pretty sure it's the first one, right? Edit: Maybe not, I'm confusing myself with random coefficients multiplied for our cause and normalisation...

[SOLVED] Quantum Mechanics - Spin Homework Statement Problem is attached. Homework Equations The Attempt at a Solution The first part is seemingly straight forward. Measurements are +/- hbar/2, both with probability (1/sqrt[2])^2 = 1/2 of being observed. For the next part I...

y = 3x*e^(-2x) y' = 3e^(-2x) - 6xe^(-2x) y'' = -6e^(-2x) - 6e^(-2x) + 12xe^(-2x) = 0 -12e^(-2x) + 12xe^(-2x) = 0 12xe^(-2x) = 12e^(-2x) x = 1 Differentiated using the chain rule (for exponentials) and product rule.

Ah I can just write it like that. It makes sense but I was worried perhaps the lecturer was looking for something more. Thanks very much!

I tried another way and got the equation of a circle! But I'm still stuck! I have (x + B)^2 + (y + D)^2 = C^2 y(a) = y(-a) = 0 (a + B)^2 + (y + D)^2 = C^2 (-a + B)^2 + (y + D)^2 = C^2 so: (a + B)^2 = (-a + B)^2 and B = 0 x^2 + (y + D)^2 = C^2 Using the constraints: y(a) = y(-a) = 0 INT[-a,a]...

Are you sure it shouldn't be lambda*(1 + (dy/dx)^2)^(1/2) + y ?

(1 + (dy/dx)^2)^(1/2) + lambda*y = F + lambda*G lambda = C dy/dx = y' No explicit dependence on x so: (1 + (y')^2)^(1/2) + C*y - (y')^2 (1 + (y')^2)^(-1/2) = A (constant) (1 + (y')^2) + C*y*(1 + (y')^2)^(1/2) - (y')^2 = A*(1 + (y')^2)^(1/2) 1 + C*y*(1 + (y')^2)^(1/2) = A*(1 + (y')^2)^(1/2) 1 =...