Recent content by phz

Unintuituve naming convention: "para-" denotes antiparallell? I did a project a week ago that required studies of the helium atom. Depending on if the two electrons spin are parallell or anti-parallell it is referred to as orthohelium (parallell) or parahelium (antiparallell). Intuitively I...

In a way alxm is describing the flux pinning effect. I don't intuitively see it as an attractive force, more as just a local potential energy minimum for the system when the field lines line up. A small movement by either object would make the field lines want to bend close to the the boundaries...

The first and second bullet point follow from the bottom of page 58. Study the expression for \epsilon_f and see how it depends on m and N / V. The third bullet point follow from the definition of k_B in a way. k_B relates energy to temperature, so the Fermi temperature associated with the...

When you use symmetry in an integral so that you don't have to integrate both parts you multiply the integral with 2 and only integrate one part since the other part will be equal to that one. You should put the _middle_ of the rod at origo and let the rod lie along the x-axis. Draw the...

Maybe they are searching for the term used to describe satellites that are kept stationary above the Earth's surface. There is a special word for this. It is a bit of a strange question if they mean it like that though, but that would be my guess.

http://en.wikipedia.org/wiki/Adiabatic_process#Ideal_gas_.28reversible_case_only.29 - The coefficient is denoted \gamma in the Wikipedia article, as is usually the case I believe.

You will have to motivate your answers more so we know why you came to them. If you just throw out an answer we can say "Wrong, try again" and nothing will be learnt. 2) is very simliar to 1), look at the motivations for the integral in 1) so you're really sure about why it looks exactly like...

Centripetal force doesn't have to be from gravity, it is just the case eg between the Earth and the sun. You have answered this in 1). The image of a circulating ball in a string is a good one. Think of the ball - what force acts on the ball? Which direction has this force? Think of F = ma.

You are integrating over r, but at the same time you set r to a fixed value \sqrt{L^2 + a^2}. It has to be a variable if you're going to integrate over it if you want some meaning from it in this case. And you don't have a term that describes the vertical component of the gravitational force...

Look at Newton's second law: F = ma. Is there a force acting on the circulating body?

I used the Minkowski diagrams incorrectly. The projection of l_2 onto l_1 wasn't perpendicular but with an angle corresponding to the time-axis for l_2, not included in my image above. At first I thought this would lead to a contradiction when I tried to project l_2 onto x', but that was because...

Calculate the wave-length of the neutron through the de Broglie-relation. Then use the Bragg condition to identify the angle.

No. The boundaries are wrong (the rod is of length 2L), you don't define which variable you are integrating over, what is your \theta and why do you use sine on it? The expression for r has to be more elaborate, and it should be squared. M/2L is the mass per unit length, that is correct...

You will have to know the distance traveled by the bike to know the amount of work done by friction. Find that out from your picture. After that use that energy is conservated as suggested. Be wary of how you define your friction. Look at the dimensions of your terms, they should always...

I would abandon the circular coordinates due to the geometry of the problem. This problem requires a bit more difficult integration and even though the answer isn't especially complex it seems like more difficult work than is intended, maybe it's meant to be done another way, but what do I know...