Recent content by y.moghadamnia

We have a sphere that its center of mass is not located in its center. suppose it has a mass of m. what we want to do here is to write its movement equations, using Newton's laws or lagranigian.by move ment we mean writing the equations if a) a force F acts on the body on a surface that is...

in line integrals we always need a vector element of distance. I can't understand the difference between ds and dr. is ds for all kinds of paths (even curly ones) and dr only for straight lines, or theyre the same? I am confused, or maybe dr is just the magnitude of ds, and the vector here is...

hi, I am looking for a topic too! it might not be the right place to right this but I couldn't acces the right page...could u guys help me too? I have passed these courses: EM, QM, Mechanics and physics 1,2and 3. and of ccourse calculus and dif equations...I have abs NO IDEA! can u tell me sth?

here is the thing, I have understood this in dielectrics, and I know that we have a new vector field instead of E, the displacement that is not neccessarily conservative. what I was thinking is that all these books, when they want to drag this law out of the info we already had, just try to make...

the title is pretty clear, so we have this F=q( E+V/c X B) the force for a point charge q in an electromagnetic field. and we have the formula to the hamiltonian of electromag force: H= (P+ q/c.A)/2m _ e\phi. the question is how can I get the F from the hamilton principle, using the...

hey there there is this thing we learn in complex analysis (and almost everywhere) that if a function is analytic in a known region, then the integral on a closed path(say, any loop), will be zero. so there is another statement we need to deal with hear, which is exactly the opposite, that if...

hi there I have been studying Purcell textbook and I think I have some trouble understanding the E dfinition it gives. ok first of all when it starts to define it, it says :"suppose we have some arrangment of charges fixed in space". so they don't move at all. then it says "we are not...

well, yeah, of course, my favorite textbook is QM by shankar, its a great one but doesn't have many problems.u can also use books by Zettili, byron and shaums problems. u can go to [PLAIN]www.library.nu[/URL] and after registration u can search all the QM books and also download 'em. good luck!

why would u be depressed at all? physics is about failing more and winning less, all sciences are, and what we truly do is never quit. good luck!

well, I am not so sure about ur question but there is no certain law to tell us how exactly we adjust in QM or such, while moving from classical physics.we need to work with eyes wide open and we need to get it right, in QM so many things are not correct according to the physics principles. but...

yeah, I know that. my question is how to change the diffrentiates from respect to x to for example r and theta. I know they might be easy using the chain rules, but I always get so confused on this and thought maybe sb could help me write it

thanx for the nice example which I completely understood, but I still feel like my knowledge on this subject is a bit bald! can u suggest me anything good to read? I have had churchill complex analysis and it was o.k, but I think I need more examples.

are u talking about QM complications? I mean we have the correspondance principle but when we enter QM we need to adjust, is that what ur saying?

hey there, I just studied the whole taylor and laurent series, and I think I mixed them up alittle.so here's what I know: - if we have a contor in which our f(z) is analytic completely, we can expand it in taylor series. - if we have singularities, we can expand the functions around the...

I know this might be a little not-so-mathematical, but u know whenever I need to expand a function, taylor or whatever there is, I imagine that so many functions can have values there, like strings floating in the plane :-) now in a point and a little bit farther(of a known function), our...