# Search results

1. ### Interesting argument between friends

Tell him to take physics again because he clearly missed the point. Yes, 1000 watts is 1000 watts, but a heater turns (most) of that energy to thermal energy whereas any other device converts some of that energy to some meaningful work. But you want an example. So lets say we have a (massless)...
2. ### Many body 2nd order energy shift of ground state

This is more of a math question I suppose, but its in the context of calculating the second order energy shift in the ground state energy for a non relativistic collection of electrons. We end up showing that the energy shift has a finite and divergent piece. The divergent bit is proportional...
3. ### Separable Scattering

Homework Statement Obtain the analytic expression for the N-channel T-matrix assuming a separable potential. Hint: assume that T is proportional to V. Specialise your answer to N=1 and perform the required integral to get an explicit form for T, assume the given form for g(k)...
4. ### Eigenvalues using rgg.f

Ok, solved the problem. It was really stupid too. I was throwing "0" into the subroutine but i had to define variables that are zero to put into the code. Rookie mistake.
5. ### Eigenvalues using rgg.f

Hey folks, I'm having an issue using a routine from the netlib that is supposed to calculate eigenvalues and eigenvectors. The canned routine can be found here: http://www.netlib.org/seispack/rgg.f I want to find the eigenvalues of a matrix (a more complex hamiltonian), so for my simple...
6. ### Schools Grad school is crushing my soul.

Thanks for all the tips folks.
7. ### Schools Grad school is crushing my soul.

Ok, I'll add that one to the list. I'll also peruse my copy of Fowles and Cassiday to see if theres anything helpful in there.
8. ### Schools Grad school is crushing my soul.

Unfortunately my undergrad mechanics completely omitted Lagrangian mechanics and everything thereafter, so this is the first time, heh.
9. ### Schools Grad school is crushing my soul.

Thanks Fred, I'll hit the library up tomorrow and look for those :)
10. ### Schools Grad school is crushing my soul.

Sounds about right then. If I get 6 hours of sleep I consider myself lucky.
11. ### Schools Grad school is crushing my soul.

The book we're using for mechanics is "Theoretical Mechanics of Particles and Continua" by Fetter and Walecka. I've never had as much trouble understanding physics as I am now. I am absolutely confounded when it comes to Lagrange multipliers, Euler angles (and other rigid body stuff) and...
12. ### Proof involving surjective/onto and image/preimage of sets

Well f^{-1} : B \rightarrow Y So let x be in B as you said. Now f^{-1}(x) is an element of Y provided that there is some y in Y such that f^{-1}(x) = y . This is where you need to use surjectivity. Hope this helps.
13. ### Newbie at Quantom Physics here!

Just an fyi, in high school I absolutely hated math. Nothing really "clicked" until I hit calculus. At that point, the reasons for all previous work became obvious. Maybe check out some lectures on youtube before deciding you can't put up with the math.
14. ### Quantum Mechanics (Basic) Problem

So in part a, you seem to have a "g" floating around. It looks like you assumed the final potential energy is gravitational. The final potential energy should be for electric charges, neglect gravity.
15. ### 2.2 Set Operations: Discrete Mathematics and its application

Any time you prove subset relations, you have to show that any element of the subset is an element of the parent set. Let x be an element of the subset, show it is in the parent set.
16. ### Acceleration Help?

So a general way to go about kinematics problems: - Note that in all of the equations only 5 variables appear: t, \Delta x, v, v_o, a - These represent time, displacement, final velocity, initial velocity and acceleration. - Each individual equation only contains 4 variables. - Generally you...
17. ### Acceleration Help?

Kinematic equations are listed here. http://www.physicsclassroom.com/class/1dkin/u1l6b.cfm Its like the 2nd hit on google when you search for it.
18. ### Acceleration Help?

So the equation you listed, V^2 = V_o^2 +2a \Delta x Has 4 variables, none of which are time. I suggest you look at the kinematic equations and select the one with all of the variables you have and need to solve for. So the variables you already know (or can deduce) are what? (ie...
19. ### Force on a Torus.

Yeah, that was the TeX problem. Thanks :) Also, it might be of interest to know that: \left| r_{i,j} \right| = min( \left| x_i - x_j \right|, L - \left| x_i - x_j \right| )
20. ### Force on a Torus.

The problem is with calculating the force of a particle by another particle while both particles lie on a torus. By this I mean, if particle i and j are in a box (LxL) and particle i is on the left edge of the box and particle j is on the right edge of the box, the distance used in the force...
21. ### Argon gas in a Box (torus)

So I've convinced myself that my updating of positions is valid. However, I am still receiving final positions outside of the box. This is my entire code. Perhaps someone can find the error. Note, I intend to randomize the starting positions and velocities once I get this to actually work. ...
22. ### Argon gas in a Box (torus)

Final shameless bump before abandoning hope for a reply.
23. ### Simultaneous Equations From Kirchhoff's Rules

You should just have to move all the terms with I3 to one side of the equation and factor out the current. That should give you an answer for I3.
24. ### Spring Stretching Problem

Looks good. Didn't check numbers. Glad I could help. Good luck on your future physic endeavors.
25. ### Exponential Equation In Quadratic Form

You could write 3^(x+1) = 3^x * 3^1
26. ### Spring Stretching Problem

So the spring is hanging. Its not accelerating. Its just dangling there. So sum of forces is zero. Try that.