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seen Mar 13 '12 at 6:18

Mar
13
comment Black body balloon in vacuum
Yeah I guess I should have worked that out from the fact that the pressure is kept constant. Once again, thanks for everything!
Mar
13
comment Black body balloon in vacuum
Huh...no where does the problem say that energy is being lost for that, which makes sense, I just thought they might have included it. That's irritating. Thanks for your help!
Mar
13
comment Black body balloon in vacuum
So for part c), I am supposed to get: (9*N*k*T_i*r^2*r')/(2r_i^3) and I am unsure how to get to that.
Mar
13
awarded  Scholar
Mar
13
accepted Black body balloon in vacuum
Mar
13
comment Black body balloon in vacuum
But what about the law that dU = TdS - PdV? Pressure is basically held constant for the sake of the problem, volume changes based on radius?
Mar
13
comment Black body balloon in vacuum
Oh I see, vacuum makes the work 0. So basically since everything else is held constant, the only thing affecting both the energy radiated and internal energy is the surface area, which is determined by the radius.
Mar
13
comment Black body balloon in vacuum
To clarify, Q is the energy? Not the heat? Then what I wrote for part b is basically correct? Also for part c, the internal energy shouldn't be the same as the emitted energy right?
Mar
13
asked Black body balloon in vacuum