Recent content by Bobbo Snap

To 1ledzepplin1: I originally wanted to use electromagnets as well. My advisor, who worked in aerospace for many years, believes that generating enough power to operate the electromagnet for any significant period of time will be the problem. I'm using the permanent magnet array at his...

They wouldn't. I suppose slow-pull would be a better name in this case but slow-push is what it's called in the literature. "Slow-push methods" encompass a multitude of techniques that are designed to work over an extended period of time, as opposed to a nuclear blast, kinetic impact, etc.

For my senior physics research project I've developed an orbital analysis program that calculates the minimum \Delta V required (applied in an instantaneous impulse) to deflect an inbound Earth impacting asteroid. I've generated data for several different hypothetical orbits and now my advisor...

Thanks, that does look like the geometry of this problem. I think the ratio \rho_1/\rho_2 is the constant M it's asking for but I'm not sure how the potential values were found. I will study it some.

Anyone? Am I correct in thinking that the image is on the other side of the plane? Any hints on how to to find M ?

Homework Statement A long conducting cylinder bearing a charge \lambda per unit length is oriented parallel to a grounded conducting plane of infinite extent. The axis of the cylinder is at distance x_0 from the plane, and the radius of the cylinder is a . Find the location of the line...

I don't think I can assume small angles, nothing is mentioned about the length of the string. But I do feel like there is some simplifying assumption I'm missing.

Homework Statement Two particles, each of mass m and having charge q, are suspended by strings of length l from a common point. Find the angle θ which each string makes with the vertical. Homework Equations F_e = k \frac{q^2}{r^2}, \quad F_G = -mg, \quad F_T = \text{tension on string}...

\langle \psi_3^0|H'|\psi_1^0 \rangle = \frac{2 \alpha}{a}\int \sin{\frac{3 \pi x}{a}} \sin{\frac{\pi x}{a}} \delta(x - a/2) = \frac{2 \alpha}{a} \sin{\frac{3 \pi}{2}} \sin{\frac{\pi }{2}} = - \frac{2 \alpha}{a} I worked out something like this for all three terms (m=3, m=5, m=7). Is that the...

Homework Statement Suppose we put a delta function bump in the center of the infinite square well: H' = \alpha \delta(x -a/2), where \alpha is constant. a) Find the first order correction to the allowed energies. b) Find the first three non-zero terms in the expansion of the correction...

Thanks PhysicsGente, your expression is exactly what I keep getting. That is, [H, r \times p] = [H, r]\times p. Maybe my mistake is trying to follow a solution I found which includes an extra term. It begins with the commutator reversed though, like this: [r \times p, H] = r \times [p, H] +...

Homework Statement Show \frac{d}{dt}\langle\bf{L}\rangle = \langle \bf{N} \rangle where \bf{N} = \bf{r}\times(-\nabla V) 2. Homework Equations . \frac{d}{dt}\langle A \rangle = \frac{i}{\hbar} \langle [H, A] \rangle The Attempt at a Solution I get to this point...

Ok, so I can simplify that last equation to get [L_z, H] = \frac{1}{2m}[L_z, p^2] + [L_z, V] =\frac{i\hbar}{2m}(p_y^2 -p_x^2) + [L_z, V] How does this imply V must be a function of r? (I guess I should have seen this from the form of the Hamiltonian).

Homework Statement Show that the Hamiltonian H = (p^2/2m)+V commutes with all three components of L, provided that V depends only on r.Homework Equations In previous parts of the problem, I've worked out the following relations: [L_z,x] = i\hbar y, \quad [L_z,y] = -i\hbar x, \quad [L_z, z] =...

Oh, never mind. I think I can commute momentum and position operators acting on different variables. So xp_z = p_zx .