Hi
A couple of years ago I was in your shoes, wanting to do a PhD and also study in the states. I ended up staying in the UK because the cost of studying in the states was prohibitive, and also I'd already done a Masters course, so the thought of spending 2 years redoing all the stuff I'd...
No-one has successfully imaged an extrasolar planet yet, but we're getting closer!
http://www.roe.ac.uk/atc/news/pressrelease/20031201/index.html [Broken]
Jess
The two-accelerated-particle case has a higher total energy (invariant mass/energy + kinetic energy) than the one-accelerated particle case, so if the two particles were to annihilate on contact, for example, the EM radiation produce in the first case would have higher energy (higher frequency)...
It looks very much as if every galaxy with a central bulge has a black hole. But bulgeless galaxies such as M33 do not appear to have sufficient central stellar velocity dispersions to contain central supermassive black holes. Until enough nearby galaxies have been surveyed, however, that'll...
The Higgs boson is required to explain why the particles that mediate the weak nuclear force - the W and Z - are so massive. The extraordinarily high masses of these particles are mathematically inconsistent with the Standard model, so particle physicists postulated the existence of another...
I found values ranging from 385 W /m K to 400 W/ m K. So I suspect this is the difference between mks and cgs systems of units.
I don't get 68W, even when I use cgs units - unless I use cm for the thickness and m for the diameter, interestingly.
Jess
The 0.5MW is only the heat conduction rate - it says nothing about how much of that heat is actually transferred to the water. There'll be losses and all sorts. I suspect that these points (plus some others that haven't occurred to me) will make up the second part of part (b)...
Jess
Try
http://personal.cityu.edu.hk/~bsapplec/newpage218.htm
It seems to answer some bits of your question. From what I've found, it looks like you can combine thermal resistances in series the way you've done it.
Jess
Sorry to point out the obvious, but this isn't an electrical conductivity question, so that comparison just doesn't stand up.
The thing is, in this question the temperature gradient is high - 20,000 K/m, which is what gives the high rate of thermal conduction.
Jess
0.5 MW isn't that big - and don't forget that the thermal conductivity of copper is unusually high. As far as I can tell from a quick dimensional analysis the units are all okay, so the answer should be correct.
Jess
I assume that the tank empties because the gas inside is at greater than atmospheric pressure. When the valves are opened the tank pressure changes until the pressure in the tank is the same as the pressure outside the tank. This way it doesn't matter how the tank empties as long as the...