# Search results

1. ### Research assistant wages?

Ya, Norman. I do need to incorporate fringe benefits as well. If you happen to have your proposals easily at hand then that would be great. If not, don't worry about it. The PhD is not necessarily in physics. In this particular case, we have a Biochemist, a Physicist, and a Materials...
2. ### Research assistant wages?

So I have to put together a mock budget for a funding proposal. I am unsure, however, how much I need to pay the research assistants I will have working on the project. I also don't have a good idea of how much a professional with a PhD or master's would be paid to work on a project. I...
3. ### Best Guitarist Ever

Marty Friedman and Jason Becker. Just listen to this song Concerto.

Doe anyone have any actual research experience? Like the guys above said, what can you actually do with only a couple years of undergraduate education?

Hi guys, This summer I am looking to get involved in research at my university. I am eager to go and meet with a professor to see if I can hold a position for him, but I am very intimidated and I sometimes feel like I don't know enough to contribute to a research team. I have been told...
6. ### Inertia tensor

Okay, so I think I figured out my problem. I was doing something wrong with the component form. Here is what I got for my inertia tensor: I_11 = 0 I_22 = (1/3)ml^2 I_33 = (1/3)ml^2 I_12 = I_21 = 0 I_13 = I_31 = 0 I_23 = I_32 = 0 So it looks something like this...
7. ### Inertia tensor

Homework Statement A thin rod has mass M and length L. What is the moment of inertia tensor about the center of mass if placed along the x axis. Homework Equations I would write the inertia tensor in component notation, but I don't know how to use Latex. The Attempt at a Solution...

Any ideas?
9. ### Energy in infinite square well

I don't think it's an algebraic error. I have worked the problem through, once using endpoints x=0 and x=L and again using x=-L/2 and x=L/2 and I don't get the same answer. In the case where I am going from 0 to L, I get that the energy is E=(n^2*h^2)/8mL^2, which is correct. In the case...
10. ### Energy in infinite square well

Homework Statement Find the energy of a particle of mass m in an infinite square well with one end at x=-L/2 and the other at x=L/2. Homework Equations Schrodinger Equation The Attempt at a Solution To save time, I won't type the solving of the differential equation which results...
11. ### Relative speed of two particles

Nevermind, I got it. Thanks SammyS.
12. ### Relative speed of two particles

Okay, so v dot u in the denominator will be zero, leaving just the 1. However, I'm still confused about u(perp) and u(para). Wouldn't u(perp) just be u and u(para) just be zero?
13. ### Relative speed of two particles

Homework Statement One particle is shot in the x direction at speed u and a second is shot in the y direction at speed u as well. Show that the relative speed of one to the other is: u(2-(u/c)^2)^1/2. Homework Equations velocity addition: u = (u' +/- v)/(1 +/- u'*v) Lorentz Trans...

Yes, you're right. I had drawn my line incorrectly. Instead of drawing it as .8c I drew it as 5/4 c. I've got it now. Thanks.

Each of the spaceships are moving towards each other. So the ship that launches from x=0 is moving towards x=4 and vice versa. I am giving the coordinates as (x,t).

Homework Statement Two rockets are sent off at t=0, one from x=0 and the other at x=4. The rocket leaving from x=0 is moving at .8c and the rocket leaving x=4 is moving at .2c. When the paths of the two rockets meet, they send a light signal to x=0. Read off the coordinates in the S frame...
17. ### Central force motion

Homework Statement Sketch the elliptical and hyperbolic orbits two objects make around each other if their masses are equal. Next to each, sketch the equivalent one-body orbit. Homework Equations The Attempt at a Solution For the elliptical orbit, I just drew two ellipses that...
18. ### Differentiating a constraint equation

Okay, thank you. That is what I was looking for. I just wasn't sure if I had to treat my r' as another variable or if I could consider it to be constant with the 2c. Thanks very much.
19. ### Differentiating a constraint equation

Homework Statement z = cr^2 Homework Equations The Attempt at a Solution I have a pretty simple question. What is the second derivative of the z equation. I know that z' = 2crr'. Am I correct to say that z'' = 2cr'^2 or is it something else? Hopefully my question...
20. ### Finding the force of constraint

So I still don't see what the point of finding this equation was. I was able to find the Lagrangian and go through and solve for the equation of motion all without having this equation.
21. ### Finding the force of constraint

You mean like 1/2Mv^2 = Mg(L - Lcos(theta)) V = sqrt[2g(L - Lcos(theta))]
22. ### Finding the force of constraint

Okay, so when swinging: T - Mgcos(theta) = Mv^2/L I still don't see how this equation helps at all.
23. ### Finding the force of constraint

Homework Statement A simple pendulum has a mass M attached at the end of a massless rod of length L. Find the force of constraint the rod exerts on the bob. Homework Equations The Attempt at a Solution It seems easy enough that the mass is constrained by the tension the rod...
24. ### Motion of a star in a galaxy

Homework Statement A star is moving in a circular orbit of radius r within a galaxy. What is it's orbital speed v(r) as a function of \rho(r) and radius. The galaxy is spherically symmetric with a mean density \rho(r) and radius R. Homework Equations F =...
25. ### Complex to polar form

What I'm saying is: x(t) = Ge^(i\phi) x(t) = G[cos(\omegat - \delta) + i*sin(\omegat - \delta) Then taking only the real part of this: x(t) = Gcos(\omegat - \delta). From here, I can compare to the given solution of x(t) = Dcos(\omegat - \delta) and say that G = D. Does this...
26. ### Complex to polar form

I am confused then because my question was from a test prep sheet from my professor. Should I perhaps only consider the real part of x(t)?
27. ### Complex to polar form

Why isn't x real?
28. ### Complex to polar form

Homework Statement Show that the solution x(t) = Ge^(iwt), where G is in general complex, can be written in the form x(t) = Dcos(wt - \delta). D(w) and \delta(w) are real functions of w. Homework Equations z = Ae^(i\phi) The Attempt at a Solution So I know I should start by...