Recent content by indie452

I am doing my revision and noticed that metals all have a molar heat capacity ~25 J/mol/K = 3R. Ionic solids such as NaCl and CaF2 however have different molar heat capacities. (~51 and 72 respectively) Why is this? there is no explanation that my lecturer gave and I can't find it online but...

Homework Statement I have been given some data, which is 20 successive 500second bins containing raw photon counts.(ie signal+data) The xray source is known to show flaring and from optical properties one suspects that it may show eclipses lasting ~1000sec. I need to estimate the...

thanks for replying so this is what i have got from your response: so if my area calculated is the prob of getting more than the chi squared (216) is 0.0345, then this means that at a 5% significance level it is unlikely that we will get a result of more than 216. but I am not quite sure...

ok so i have some data (d) of star counts (N=181), and a model (m = b-Fo where b=5 and Fo-constant flux) I have found the chi squared value = 216 I know that the number of degrees of freedom here is N-parameters = 181-1 = 180 my question is: "show that the model is not a good fit to the...

Homework Statement I have a luminosity prob distribution that i want to plot and find the expectation value and mode for. Homework Equations p(L)dL = A \frac{L}{i}^aexp(-\frac{L}{i}) \frac{dL}{i} A=const a= -0.7 i= 1.4e10 solar luminosity units lower limit = 1e9 solar luminosity...

what is meant by density, such as the baryonic matter density in cosmology, in "units of the critical density"? its mentioned in a question i need to do but i don't really know what it means.

Homework Statement I have the function (a(1+z)3 + b)-1/2 and i need to taylor expand it around z=0 to the first order, a and b are constants, there sum is equal to one. I have the answer: 1 - (1+q)z where q = a/2 - b This is in my physics book but it does not explain the...

Homework Statement Okay so i am applying a FT to an image of particles that are forming a lattice, and i need to find the average distance between the particles because its not a perfect lattice, I am getting an airy pattern and i believe that the distance to the first ring is the average...

wait is it just zero?...thats what i got from doing some rearrangement (too much to write out)

ok so on the left the Ecm is 1000GeV, is pcm2c2 = Ecm2 - m2c4 ...wait i don't think that helps... my lecturer didnt really go over how to get the momentum. the only thing he metioned ws the 4momentum but i don't think that is what i use here

well i set it to m2c4 cause this is the invariant mass and so i can find this in the lab frame and it will be the same in the cm frame. when i found the relation for this i went to the cm frame to use its Ecm to find the energy i need for the beam. now while writing this i think i should...

as in that i should have put (2m)2c4 on the left hand side?

(E+mc2) is the sum of the energies of the 2 particles. the e- is stationary so i thought that its energy is just mc2 in the lab frame p2c2 i didnt put a p(e+) +p(e-) because the momentum of e- is zero so its just the mom. of the e+

ok so i tried this instead mass of e+ and e- => m2c4 = (E+mc2)2 - p2c2 = E2 - p2c2 + 2Emc2 + m2c4 = 2Emc2 + 2m2c4 and as mc2<<E m2c4 = 2Emc2 now this is where I'm abit unsure: can i say: m2 = (1000GeV)2? cause this would give (1000GeV)2 = 2E(0.51MeV) so E = 1.96x1018eV

where is it that I've gone wrong? what would you suggest to try and get the right answer?