# Search results

1. ### Additional boundary conditions for inclined flow?

Homework Statement I am solving an inclined flow problem, and am stuck. The problem is to find the volumetric flow rate of inclined flow in a square channel. Once I have the velocity profile, I can just integrate over that to get the flow rate. 2. The attempt at a solution Letting the...
2. ### Divergence of tensor times vector

(My question is simpler than it looks at first glance.) Here is Reynolds Transport Theorem: $$\frac{D}{Dt}\int \limits_{V(t)} \mathbf{F}(\vec{x}, t)\ dV = \int \limits_{V(t)} \left[ \frac{\partial \mathbf{F}}{\partial t} + \vec{\nabla} \cdot (\mathbf{F} \vec{u}) \right] \ dV$$ where boldface...
3. ### Maximum precision of deterministic measurements

Okay, I tend to have some weird thoughts, so bear with my odd question here. Suppose you have a collection of particles that obey Newtonian mechanics. For simplification, all particles are identical and can be assumed to be hard spheres that collide elastically. Each particle has a position...
4. ### What does the lost information in the wavefunction mean?

The wavefunction is defined on the domain of complex numbers. To find the probability of discovering a particle in a certain region, the amplitude of the wavefunction is integrated over that region. The problem is that you have an infinite set of complex numbers mapping to a single amplitude...
5. ### Electrons split in two?

http://www.popsci.com/science/article/2012-04/first-time-electrons-are-observed-splitting-smaller-quasi-particles Sorry if this is old news or already posted somewhere, but could someone tell me more about this? (I know QM but not QFT, so if you can use QM terms that might be helpful). Thanks
6. ### Why is gravity special ?

Why is gravity "special"? (You may think this belongs in the General Relativity section, but the question really relates more to particle physics). As I understand it, anything with any energy whatsoever creates a disturbance in the gravitational field. So this means that the potential...
7. ### The science behind the conversion of particles to other particles

It seems kind of weird to me that particles convert between each other. As I understand it, if a positron and an electron "collide", two gamma ray photons are created, and the positron and electron are gone. 1st - What is meant by a collision? The positron and electron are each described...
8. ### Do the eigenfunctions for the position operator form an orthogonal set?

Starting with, \hat{X}\psi = x\psi then, x\psi = x\psi \psi = \psi So the eigenfunctions for this operator can equal anything (as long as they keep \hat{X} linear and Hermitian), right? Well, McQuarrie says that "the eigenfunctions of a Hermitian operator are orthogonal", which can be...
9. ### Is EVERYTHING affected by gravity?

Generalizing somewhat on my other post, I have to wonder -- if everything observable has an energy associated with it, then it is a form of mass as well, right? And all mass is affected (and causes) gravity, right? (And I don't mean rest mass -- I mean total mass.) Am I missing something...
10. ### You're all wrong about the Higgs boson! This is how it really works!

Somehow stumbled across this website Can't tell if it's made by a real physicist as a joke/parody or by someone who was dropped a few too many times. It looks like a lot of effort went into those diagrams though...
11. ### Engineering Finding Thevenin Equivalent circuit (Voc)

Homework Statement [PLAIN]http://dl.dropbox.com/u/9699560/EE%20Problem.jpg [Broken] (I added the text V1, V2, and Voc to the image). I'm only trying to find Voc because I got the wrong answer. I got Isc correct. Homework Equations Basic node voltage analysis techniques. The Attempt at a...
12. ### Gravity affecting gravity?

I was thinking about how a compressed spring weighs more than the same spring uncompressed, and it got me wondering about the earth and moon system. Basically, if you separate the two and weigh them individually, the sum is not going to weigh as much as if you weighed them as a system because...
13. ### How much of a hydrogen atom's mass is due to the mass of fundamental particles?

If one were to subtract the kinetic energies of all fundamental particles within hydrogen, as well as all of the potential energy of all bound states between these particles, how much mass (as a percentage of the total) would remain? Ignore the kinetic energy due to the hydrogen's speed. And...
14. ### Is this a good analogy to quantum entanglement?

[Sorry for asking so many questions by the way, but I enjoy learning ;) ] I've always been kind of confused with quantum entanglement, and what it means experimentally, but I just read something that someone posted on another website: Is this an accurate analogy to the situation with...
15. ### Are points of spacetime unique?

Are any known laws of physics a function of a unique spacetime coordinate? Be careful reading my question -- I'm not asking if the laws of physics vary throughout spacetime (since they don't).
16. ### Trying to understand Heisenberg Uncertainty Principle in a physical sense

I'm trying to understand the Heisenberg Uncertainty Principle, as it relates to experimental measurements, because it's kind of confusing me. We just learned the derivations for it in my QM class -- basically it's two standard deviations multiplied together (corresponding to measurements of...
17. ### Particles and position

I just started taking a Quantum Mechanics course at my university (only 3 days into it) and some of the topics got me thinking about stuff. Namely, about "particles". I searched on Physics Forums and found some other posts pertaining to my question, but a lot of the responses referenced topics...
18. ### Effect of friction on a wheel

Could someone verify that my thinking is correct, or point out the mistakes if it is incorrect? I'm trying to figure out where energy goes when rolling a cylinder down an incline. It is initially stationary. 1) First, assume there is no air resistance. If the surface of the cylinder and the...