# Search results

1. ### 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...

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...
3. ### 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...
4. ### 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...
5. ### 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...

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...
7. ### 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...
8. ### 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...
9. ### 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...
10. ### 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 =...
11. ### 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...
12. ### Driven oscillator with damping

Homework Statement The oscillator is driven by a force F(t) = mAcos(wt). Plot the amplitude D of oscillations, in units of the maximum (resonant) amplitude D(max), as a function of w in units of w_0. (In other words, plot D/D(max) versus w/w_0.) Find Q. \beta=(1/6)w_0 Homework...
13. ### Complex roots

Homework Statement Z^5 = -1 What are the five roots? Homework Equations The Attempt at a Solution I do not know how to start this problem. I am given a hint to put -1 into the form Ae^(i*delta), but I am unsure as to how I can do that. Any help would be much appreciated.
14. ### Complex notation

Homework Statement If x= Acos(\omegat + \delta), then one can also write it as x = Re(Be^{i\Phi}). Find B and \Phi in terms of A, \omega, and \delta if B is real. Homework Equations The Attempt at a Solution Not sure where to start on this one. I know you guys can't give...
15. ### Is this a vector operation

Homework Statement Consider a new vector operation, 'star' (*), defined for two dimensional vectors by A*B=(A1-B1,A2+B2). Is the resultant object a vector? Homework Equations The Attempt at a Solution I want to say that the resultant object would be a vector but I do not know...
16. ### Energy conservation and circular motion

Homework Statement A ball with a mass m swings from a string of length L from a pivot. A distance D directly below the pivot there is a nail. The ball is released making an angle theta=pi/2 with the vertical. For this particular problem, there is no friction. Assuming the ball swings...
17. ### Transformation Matrices

Homework Statement Find the components of A after a rotation of -45 degrees about X3. A=(1,1,2) Homework Equations \lambda= (cos\theta 0 -sin\theta) ( 0 1...
18. ### Bowling ball velocity problem

Homework Statement A bowling ball is initially bowled so that it doesn't roll with a translational velocity Vo. Show that when the velocity of the ball drops to (5/7)Vo, the ball will begin to roll without sliding. I= (2/5)MR^2 mass= M radius= R Homework Equations V=wR The...
19. ### Thermo final study tips

Hey guys, I have my final exam in a week for my thermodynamics class. So far this year, things have been sort of roller-coaster-like. I did poorly on my first test because I was caught completely off guard. On my second test, I raised my grade substantially to the point where I was...
20. ### Fortran Hangman in fortran

Hello all, I am attempting to make a fortran program that allows the user to play a game of hangman. So far I have written a complete program that assembles piece by piece the base, gallows, rope, body parts, etc.. I have another completely separate program that reads from a file 264 random...
21. ### Ideal gas compression

Homework Statement A compressed cylinder holds nitrogen gas at room temperature. How cold is the gas that is escaping from the cylinder? T(cylinder) = 298 K P(cylinder) = 1.034e7 Pa n = 1 Homework Equations PV = nRT The Attempt at a Solution So since I was not given either the volume of...
22. ### Physics Careers w/ physics

Hello all, I am currently pursuing a B.S. degree in physics. My main concern is finding a job that isn't just laboratory research. Can anyone give some of the popular areas that physics degrees would be applicable for? Any advice would be much appreciated.

Homework Statement Show that when an ideal gas expands adiabatically, the temperature and pressure are related by the differential equation: dT/dP = (2/f+2)(T/P). Homework Equations PV=NkT VT^(f/2) = constant V^(gamma)*P = constant The Attempt at a Solution I started off with the formula...
24. ### Finding randomization algorithm

Hello all, I am currently attempting to take a set of data I have acquired and trace it back to the initial algorithm that produced it. My problem is my math level is only at the level of differential equations and I do not have any knowledge in advanced statistical analysis. Anyone have...
25. ### Proton decay

Homework Statement Grand unification theories predict that the proton has a long but finite lifetime. Current experiments based on detecting the decay of protons in water infer that this lifetime is at least 10^32 years. Assume 10^32 years is, in fact, the mean lifetime of the proton...
26. ### Titrations and pka's

Homework Statement Weak acid analyte with strong base titrant. What is the pKa of the analyte in this titration to the nearest 0.5? Given: titrant molarity is .2250 M ; 50 mL of analyte present ; 20 mL of titrant ; initial pH of 3.0 Homework Equations M1*V1=M2*V2 The Attempt at a...
27. ### Calculate the pH of 20.00 mL of 0.20 M KHP

Homework Statement Calculate the pH of 20.00 mL of 0.20 M KHP. Given: pKa1(H2P)= 2.950 pKa2(H2P)= 5.408 Homework Equations k = [H][P]/[HP] The Attempt at a Solution I used this equation and got: 3.91e-6 = [x][x]/[.2] x^2 = 7.82e-7 x = 8.8e-4 = [H] pH = 3.05...
28. ### Buffer solutions

Homework Statement If you began with 8.5 mL of 0.35 M NaHCO3, how many mL of 0.10 M HCl would you need to add to get a pH 7 buffer? Homework Equations pH = pKa + log([base]/[acid]) or pH = pKa + log(mmol base/mmol acid) The Attempt at a Solution I have tried making a reaction table, but I...
29. ### Mean free path calculation

Homework Statement The resistivities and Fermi speeds of Na, Au, and Sn at T = 273 K are 4.2 µ\Omega·cm, 2.04 µ\Omega·cm, and 10.6 µ\Omega·cm, and 1.07e6 m/s, 1.39e6 m/s, and 1.89e6 m/s respectively. Use these values to find the mean free paths λ for the conduction electrons in these elements...
30. ### Mixtures of acids and bases

Homework Statement You prepared a reaction table for 10.0 mL of 0.1 M NH4Cl with 5.0 mL of 0.1 M NaOH. Please choose all of the following that describe the solution that was produced. The choices are: 1. a solution containing only a strong base 2. a solution containing a weak acid and a...