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Physics question

Community Veteran
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Physics question

Nephews homework again
Suppose the entire baryonic mass (subatomic particles) of the universe were converted to radiation.
What would be the temperature (K) of the resulting radiation.

I've requested more information, I don't think this is enough to go on
Anyone any ideas Huh  be glad when the rain stops and he can play football again Roll eyes
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Community Veteran
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Re: Physics question

TORPC
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Re: Physics question

Or is it your brain cell(s) will be glad of football time again Roll eyes
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Re: Physics question

HP, sorry no, that was my guess also Embarrassed involves energy to mass equation e=mc^2
@TORPC  to right Grin
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Re: Physics question

Bit different to the last homework posted  Lips are sealed
I've 'A' levels in physics and a couple in maths but I'm completely blank on this.
Do they actually expect an answer (I thought schools were supposed to be 'dumbing down' these days).
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
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Re: Physics question

I'm struggling with this one, as far as I can glean from txt messages it involves Olbers's Paradox.
following variables have been identified
Ω_r,0 4.75E-05
Ω_b,0 0.044
ρ_c,0 9.47E-27
Tr         2.73E+00
T is tempreture, ρ is density
From this I've managed to identify the baryonic matter density ρ_b,0 where ρ_b,0 = ρ_c,0/Ω_b,0 = 4.178E-28
currently thumbing my way thru "BOB" (Big Orange Book - on Physics) to find meaningful information

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Re: Physics question

Why do you need to know the density?  Huh
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Re: Physics question

I think  I've got this right, my physics is a bit dated (from BOB)
Temperature can be calculated if we know the energy density
E = mc^2 will enable the change of matter density to energy density
where m=density * volume
Then use the   Radiation energy density formula to find T
edit:- using this method I get 15.03 K, haven't told nephew, just emailed above method

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Re: Physics question

Quote from: journeys
Suppose the entire baryonic mass (subatomic particles) of the universe

Is this a trick question or something? - We don't know the size of the universe and as far as we know it's infinite so surely without that you'd not be able to calculate it the answer you want anyway?
I need a new signature... i'm bored of the old one!
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Re: Physics question

Quote from: 7up

Is this a trick question or something? -

http://en.wikipedia.org/wiki/Observable_universe#Mass_of_ordinary_matter

Think the key was 'suppose'
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Re: Physics question

Quote from: 7up
Is this a trick question or something?
Only, I suspect, in the sense that it's designed to make you think carefully about what is (and therefore ignore what isn't) relevant to the answer.
As Donald Rumpsfeld said
Quote
There are things we know that we know. There are known unknowns. That is to say there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know.
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Re: Physics question

Quote from: HPsauce
Only, I suspect, in the sense that it's designed to make you think carefully

@HP good point Wink
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Re: Physics question

When will you know the official answer, with explanation?
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Re: Physics question

about a week, he gets feedback showing the method, I'll ask for a copy, then paste it in this thread.
nanotm
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Re: Physics question

as the size of the universe is infinite, the amount of baryonic mass within the infinite universe is also infinite, then the potential conversion to radiated energy is equally infinite, if the question included the phrase "of the known quantifiable universe" then it would be a different answer involving lots of equations .....
just because your paranoid doesn't mean they aren't out to get you