# Search Results

1. Post

### B Why does the equation for elastic collisions work like this?

Because you have an arithmetic error here. You should get $v_1 + v_1' = v_2$.
Post by: Orodruin, Feb 22, 2017 at 3:13 AM in forum: General Physics
2. Post

### I Basic bra-ket arithmetic

No and no.
Post by: Orodruin, Feb 20, 2017 at 4:14 PM in forum: Quantum Physics
3. Post

### Unit vector perpendicular to the level curve at point

A level curve of a function is the curve such that the function takes a fixed value. For example, the level curves of f=x^2+y^2 are circles.
Post by: Orodruin, Feb 20, 2017 at 11:14 AM in forum: Calculus and Beyond Homework
4. Post

### Using momentum conservation as holonomic constraint

This is what I thought. You are a priori not allowed to think in terms of forces. They are not part of the basic formalism. The identification of...
Post by: Orodruin, Feb 20, 2017 at 8:56 AM in forum: Introductory Physics Homework
5. Post

### Using momentum conservation as holonomic constraint

Because momentum conservation is derived as a constant of motion from the variation of the action. Of course you could assume momentum...
Post by: Orodruin, Feb 20, 2017 at 3:18 AM in forum: Introductory Physics Homework
6. Post

### Using momentum conservation as holonomic constraint

Yes, you cannot just assume momentum conservation (which is what you do if you put it in as a constraint). In the cases where you do have it it...
Post by: Orodruin, Feb 20, 2017 at 12:41 AM in forum: Introductory Physics Homework
7. Post

### B What would things look like if PI = 3.

The question is meaningless. It is like asking what the world would look like if 1=2 or if white was black.
Post by: Orodruin, Feb 20, 2017 at 12:33 AM in forum: Differential Geometry
8. Post

### I Dimensional Analysis Poisson Equation

The potential is arbitrary. You can shift it by a constant and still satisfy the Poisson equation.
Post by: Orodruin, Feb 19, 2017 at 1:16 AM in forum: Classical Physics
9. Post

### I Identifying gluon in Feynman diagram

No. The idea is the same. You can draw a valid Feynman diagram but the symmetry of the in state makes it equal to zero.
Post by: Orodruin, Feb 19, 2017 at 1:02 AM in forum: High Energy, Nuclear, Particle Physics
10. Post

### I Identifying gluon in Feynman diagram

Post by: Orodruin, Feb 17, 2017 at 1:09 PM in forum: High Energy, Nuclear, Particle Physics
11. Post

### I Photon Polarization

Not right. $p$ is a fixed vector, $p_i$ is its ith component.
Post by: Orodruin, Feb 17, 2017 at 1:07 PM in forum: High Energy, Nuclear, Particle Physics
12. Post

### I Identifying gluon in Feynman diagram

Yes.
Post by: Orodruin, Feb 17, 2017 at 12:52 PM in forum: High Energy, Nuclear, Particle Physics
13. Post

### I Photon Polarization

Why do you think the RHS would be zero?
Post by: Orodruin, Feb 17, 2017 at 12:51 PM in forum: High Energy, Nuclear, Particle Physics
14. Post

### I Identifying gluon in Feynman diagram

It is not an SU(3) singlet. The a is an index of the 8-irrep.
Post by: Orodruin, Feb 17, 2017 at 12:23 PM in forum: High Energy, Nuclear, Particle Physics
15. Post

### Can arXiv papers be considered as reliable sources of information?

I would agree that this is a possibility among many. Unless you know (professionally - not that they are your friends) the authors are reliable,...
Post by: Orodruin, Feb 17, 2017 at 4:00 AM in forum: General Discussion
16. Post

### Unit vector perpendicular to the level curve at point

Yes. Is that a problem?
Post by: Orodruin, Feb 17, 2017 at 12:50 AM in forum: Calculus and Beyond Homework
17. Post

### Solution to complex valued ODE

What is $|e^{x+iy}|$? If $f(t)$ has a real part, what happens to the solution?
Post by: Orodruin, Feb 16, 2017 at 10:59 PM in forum: Calculus and Beyond Homework
18. Post

### Solution to complex valued ODE

What happens if you differentiate z/w?
Post by: Orodruin, Feb 16, 2017 at 10:39 PM in forum: Calculus and Beyond Homework
19. Post

### A matching interaction terms and decay processes in standard model

You are missing minus signs in your projection operators. CC iteractions act on left-handed fields only. 1,2) Yes. 3) No, you need the lepton...
Post by: Orodruin, Feb 16, 2017 at 10:37 PM in forum: High Energy, Nuclear, Particle Physics
20. Post

### I Identifying gluon in Feynman diagram

You cannot make a pure $r\bar r$ from those combinations. The 8 representation is traceless.
Post by: Orodruin, Feb 16, 2017 at 4:15 PM in forum: High Energy, Nuclear, Particle Physics
21. Post

### Can arXiv papers be considered as reliable sources of information?

In general, but not as a general rule. For example, people will also put thing such as lecture notes and PhD theses on the arXiv. These are...
Post by: Orodruin, Feb 16, 2017 at 6:42 AM in forum: General Discussion