# Recent content by Yosty22

1. ### Correct option for n dependence of free energy f per unit

If you know these are free particles (i.e. potential energy term in the Hamiltonian is 0) then the best start would be to calculate the N particle partition function, it's usually called Z or QN. Once you have the partition function, the Helmholtz free energy is given by: A(N,T,V) = -kTln(Z)...
2. ### Lagrangian for a Spherical Pendulum (Goldstein 1.19)

Yeah, I just caught the potential energy problem myself and fixed it. However, I'm not quite sure what you mean about not needing to carry out the total time derivative. In the equation for Φ, ∂L/∂Φ = 0, so this would mean that the physical quantity described by (d/dt)(∂L/∂Ω) is conserved. Am I...
3. ### Lagrangian for a Spherical Pendulum (Goldstein 1.19)

Homework Statement Find the Lagrangian and equations of motion for a spherical pendulum Homework Equations L=T-U and Lagrange's Equation The Attempt at a Solution [/B] I found the Lagrangian to be L = 0.5*m*l2(ω2+Ω2sin2(θ)) - mgl*cos(θ) where l is the length of the rod, ω is (theta dot)...
4. ### What do astrophysicists do?

I'm also not an astrophysicist, but I have worked with some and I can say that having some background in computation is very helpful. i.e. computational physics, coding, model making, etc.
5. ### Other Does NSF care about GPA? (After 1 year in Grad)

I can give some personal experience on the matter, but not your exact situation. For a bit of back story, I applied for the NSFGRFP after my senior year of undergrad as I was applying for graduate school. At the time, I had 2 and a half years of research experience, one first-authored paper, one...
6. ### Schools Starting university (physics)

Often, the hardest part about some of the introductory physics problems is figuring out what you're being asked and how to proceed with a solution, not necessarily the solution itself. Don't worry about failing, but I agree with MidgetDwarf: you definitely need a really solid grasp of all of the...
7. ### Computational Introduction to Computational Physics Texts?

Hi all, I'm starting graduate school and really need a better handle on computational physics. I'm not extremely experienced with MATLAB and haven't used Python or anything else. Does anyone know a good textbook to get me started? I looked in the textbooks links to this forum thread and the...
8. ### Vector problem

î + ĵ + √2k̂ is a vector made up of three components, but it corresponds to a single vector. From my interpretation of the question, I would assume the question expects three answers (which is seems like it does). Rather than finding the angle î + ĵ + √2k̂ makes with î + ĵ + k̂ you are finding...
9. ### B Are photons particles or waves?

I believe what he means in regards to the consideration of the presence of an eather is that all waves travel in some medium. It was reasonable to say that if every other type of wave travels through a medium, light must as well. However, looking out in space, near vacuum, there is no such...
10. ### B Are photons particles or waves?

You can even do Young's double split experiment with single photons and still observe the diffraction pattern on the back screen. Thus, you can describe the photons as waves. Yet, if you tried to measure which slit the photon was going through, you lose this diffraction pattern on the back end...
11. ### A Raman Spectroscopy vs. Inelastic Electron Tunneling

I am a first year graduate student in physics and am becoming familiarized with Raman spectroscopy to study structure of materials based off of their vibrational states. In some personal study outside of this, I came across the idea of inelastic electron tunneling spectroscopy (IETS) and was...
12. ### Lagrangian Mechanics Problem

Update: I should probably transform to coordinates like (r,theta) and find theta dot, right?
13. ### Lagrangian Mechanics Problem

Homework Statement We have a particle of mass m moving in a plane described by the following Lagrangian: \frac{1}{2}m((\dot{x}^2)+(\dot{y}^2)+2(\alpha)(\dot{x})(\dot{y}))-\frac{1}{2}k(x^2+y^2+(\beta)xy) for k>0 is a spring constant and \alpha and \beta are time-independent. Find the normal...
14. ### Calculating Displacement

In general, I believe pictures always make this more intuitive and easy to understand. If you drew a picture of the case you presented in the original post, it would be evident that the two points lie on the same horizontal line. In this case, your method works. However, in the case I gave as...
15. ### Calculating Displacement

You can do this for this example. With how you described it, it like taking the x-axis. There, you would be setting the 0 point at the origin, such that any distance westward (in your case, the 23m) is negative and anything eastward positive, which is legitimate. The only time this may get a bit...