Recent content by truth is life

Which I noted...twice...in my own replies. And it turns out the whole problem was...I was doing the multiplications wrong :facepalm: Everything else was right(-ish), I just messed up the basic arithmetic. Gets you every time.

Well, the book (which is not the book the problem comes from, to be clear) defines ##Q## slightly differently; if ##e## is the vector in the old basis and ##E## the vector in the new basis, then $$e = QE$$ whereas I was calculating ##Q## in the straightforward way as $$E = Qe$$ Both are valid...

The old basis is the standard x-y-z Cartesian basis. The new basis uses the ##e^{\left(x\right)}## vectors as the basis. So, in the old basis $$e^{\left(0\right)} = \begin{bmatrix}0 \\ 0 \\ 1 \end{bmatrix}$$ whereas in the new basis it would be $$e^{\left(0\right)} = \begin{bmatrix}0 \\ 1 \\...

It was essentially a guess-and-check-type method. I knew that in the old basis the new basis vectors had the particular form in the problem; I also knew that in the new basis they should take on a known different form (##e^{\left(1\right)} = \left(1, 0, 0\right)##, for example). I then...

Homework Statement Consider the three operators defined by $$\left(S_i\right)_{jk} = -i\epsilon_{ijk}$$ in the x-y-z space and the basis vectors given in x-y-z space as $$e^{\left(1\right)} = -\frac{1}{\sqrt{2}}\left(e_x + ie_y\right), e^{\left(0\right)} = e_z, e^{\left(-1\right)} =...

Oh no, not at all. A significant amount of time per problem is expected at higher levels, in mathematics and physics both. It often takes quite a bit of wrestling before you can see the way through.

Yes. Professors almost always assign a particular book, then use that book, whether by structuring the class in the same fashion that the book is structured or by assigning problems out of the book. It is quite unusual for this not to be the case (I personally have only had one class, in any...

The problem statement says that the entire white dwarf is carbon fusing to nickel. How much energy would that release, given that each fusion process releases 280 MeV? (They're clearly just going for a reasonable/approximation approach, so you're overthinking it)

Well...fairly sure. (It's a lab, you see, so I'm basing this off of our collected data...which might have mistakes!) I used the equation (can't quite remember how to do latex here) a*sin theta = m*lambda lambda is definitely 633 nm (we're using a HeNe laser), m is one. So that means we have...

Homework Statement From the intensities of the first-order peaks in the spectrum of a diffraction grating with monochromatic (633 nm) light shining on it, estimate the aperture size. Also known: grating constant (20 nm), distance from grating to screen (25 cm), positions of first-order peaks...

I don't think you need to do any calculations here. Just remember the definition of the half-life and the amount of time that's passed, then get the fraction of the original atoms that remain (you don't even need to do a precise calculation, just a Fermi estimate would be more than enough to...

Homework Statement In a Young's double slit-type experiment using light of 600 nm with 0.5 mm between fringes, a thin plate of glass (d = 100 micrometers, n =1.5) is placed over one of the slits. What is the lateral fringe displacement on the screen? 2. The attempt at a solution To be...

I believe the OP is asking something somewhat subtler than that, to wit if they are NOT rotating, and there is no mechanism (like air resistance) to make them rotate, then is there any apparent force at all? Ie., what the inertial observer sees is actually a spacesuited astronaut (or a rock...

Ah! You're in MY class! Houston, right? I think I can guess (to 2 people) who you are, too...

So was my class...hmm, this is getting suspicious...who's your professor? (Last name's fine) I agree that G. is pretty useless (and in fact have refused to even consider going to Minnesota for grad school); I've bought at this point 4 other books (Griffith's, Dirac's, Bohm's, and now...