Recent content by ted1986

Hi, I've got a question about fitting a known function to a measured data. Suppose I want to find X parameters by fitting a curve to some measurments - What is the minimum number of measurements needed? Someone has told me that I need X+1 measurments, (because one degree of freedom), but...

Thanks! I'll try it... Do I know you from somewhere ? ;-)

Hi all, I've got this problem (which is attached as q1.jpg). I've tried to solve it, but I'm stuck... my solution is also attached (my_sol1.jpg). PLS help me :-( Thnx TED

There is the equation F=-((4*a*c)/(3rho*kappa))*T^3*(dT/dr), but I don't think it's the right equation to use...

Hello all! I have to calculate the required mass to ignite the PP chain when the given temperature is 4*10^6K and \mu=0.62. (I know the answer is about 8% from the sun's mass)… I don't know exactly how to do it :-/ I know that (R/Rsun)=(M/Msun)^(3/7), The energy per nucleon in PP process is...

Hello! I've got this question (attached as jpg) about the neutrino fluxes at earth. I don't know how to use the branching ratios in order to solve it. (Do I really need these ratios?) Thanks. Ted.

Thank you for your efforts :)

OK, I tried to solve the exercise as you said (P=K*rho^\gamma), but the equaion I've got seems to be to complicated... (my derivation is attached - star_my_sol2.jpg) Perhaps the derivation needed to solve it is less complicated? Thank you.

Hello again, I've got a question about a star in a hydrostatic equilibrium. How do I derive an equation of motion for a pertubation in the full momentum equation? I'm attaching my solution (my_solution.jpg) , but I'm not quite sure about it. The full exercise is attached as...

OK, It sure gives a simple derivation of the differential equation, but what is the physical explanation for that? Thanks

Hello, I'm trying to derive a differential equation as requested in the attached exercise (thermal1.jpg). I'm not quite sure my solution is the right answer (my_solution1.jpg). How do I get rid of the energy dU ? Thnks Ted

Solved! Thank you so much!

OK, I expressed dS, but it looks different from the final term (File is attached). Another question - the p (from the relation TdS-pdV=dU) - is it the total pressure? and if it is, how is it expressed?

Thank you for your answer. I used the relations you wrote, and it looks like I'm in the right direction, but as you can see in the attached file – I don’t know how to use the entropy dS instead of dU. B.T.W - Where can I find explanations about the relations you wrote? Thank you.

Hi, I'm trying to solve the attached exercise, but I'm not sure I'm in the right direction. What I've been trying to do is using the relation: dU=TdS-pdV Dividing it by T and adding dT so the relation will be (dU/T)dT=(ds/dT)-pT(dVdT), but I don’t think it’s the right way to solve it...