amazing statistic of the day
- Thread starter bobg
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[astrophysics hat on]Yup, sounds plausible (though I haven't looked up any figures). The Sun produces all its energy by fusion, in a relatively small volume right down at its core, and the rest of its bulk is merely engaged in transmitting that energy to the surface where it then gets radiated out to us.[/astrophysics]The Velvet Curtain said:
- Location
- the post-brexit wasteland
when living with sheryl crowe, lance armstrong used to go though 5 pairs of pants a day, as bog roll was strictly rationed. the old pants would be sold in aid of local charities.
cisamcgu
Legendary Member
- Location
- Merseyside-ish
Hmmmm ...The Velvet Curtain said:
Volume of the Sun = 1.4122 × 10^21 m³
Energy production by the sun = 3.83 × 10^26 W
Therefore energy per cubic meter of "sun" is approx 2.7x10^5 W/m³
or 270KW - I really doubt that the human body produces anything like that - considered opinion is of the order 200-300W
(my maths may be completely poo of course, it is a looooong time since school)
Andrew
cisamcgu
Legendary Member
- Location
- Merseyside-ish
Oh well, it seems my maths is completely poo as I suspected ....
From wiki :
About 3.4 × 1038 protons (hydrogen nuclei) are converted into helium nuclei every second (out of ~8.9 × 1056 total amount of free protons in the Sun), releasing energy at the matter–energy conversion rate of 4.26 million tonnes per second, 383 yottawatts (3.83 × 1026 W) or 9.15 × 1010 megatons of TNT per second. This actually corresponds to a surprisingly low rate of energy production in the Sun's core—about 0.3 µW/cm³ (microwatts per cubic cm), or about 6 µW/kg of matter. For comparison, the human body produces heat at approximately the rate 1.2 W/kg, millions of times greater per unit mass.
But that is energy per kg not energy per m³, so maybe I am still right ... who knows
From wiki :
About 3.4 × 1038 protons (hydrogen nuclei) are converted into helium nuclei every second (out of ~8.9 × 1056 total amount of free protons in the Sun), releasing energy at the matter–energy conversion rate of 4.26 million tonnes per second, 383 yottawatts (3.83 × 1026 W) or 9.15 × 1010 megatons of TNT per second. This actually corresponds to a surprisingly low rate of energy production in the Sun's core—about 0.3 µW/cm³ (microwatts per cubic cm), or about 6 µW/kg of matter. For comparison, the human body produces heat at approximately the rate 1.2 W/kg, millions of times greater per unit mass.
But that is energy per kg not energy per m³, so maybe I am still right ... who knows
Arch
Married to Night Train
- Location
- Salford, UK
bonj said:
People don't give off heat eh? Do you have any close friends? You better check they aren't all zombies. Or lizards.
Mammals use up a huge proportion of the energy they produce maintaining their body heat. It's called being 'warm blooded'. I suggest you watch more David Attenborough programmes
No one said that a human radiates more energy in heat and light than the sun, no. They said produces energy. But just to keep you warm, breathing, heart beating and brain working uses up a lot of energy. So there's not a lot left to shine with.
Arch
Married to Night Train
- Location
- Salford, UK
simoncc said:
I don't believe that. To be taught, you'd have to display a willingness and capacity to learn.
I was never told anything specific about oil running out, BTW, my school must have been an odd one out... We were told that it was a finite resource, in terms that it takes million of years to form, and minutes to use up.
papercorn2000
Senior Member
simoncc said:
There's a Transport Museum in Glasgow (very popular BTW) and there's loads of cars in it. So the prediction was at lest half-right!
cisamcgu said:Oh well, it seems my maths is completely poo as I suspected ....
From wiki :
About 3.4 × 1038 protons (hydrogen nuclei) are converted into helium nuclei every second (out of ~8.9 × 1056 total amount of free protons in the Sun), releasing energy at the matter–energy conversion rate of 4.26 million tonnes per second, 383 yottawatts (3.83 × 1026 W) or 9.15 × 1010 megatons of TNT per second. This actually corresponds to a surprisingly low rate of energy production in the Sun's core—about 0.3 µW/cm³ (microwatts per cubic cm), or about 6 µW/kg of matter. For comparison, the human body produces heat at approximately the rate 1.2 W/kg, millions of times greater per unit mass.
But that is energy per kg not energy per m³, so maybe I am still right ... who knows
Anyone know the mean density of the Sun?.... All I know is that I heard it on Horizon, and the BBC would never lie to us.
About 1.4 times that of water, therefore one m³ will weigh about 1400Kg and yield (according to cisamcgu's figures) about 8.4 milliwatts.The Velvet Curtain said:Anyone know the mean density of the Sun?.... All I know is that I heard it on Horizon, and the BBC would never lie to us.
Remember that the Sun - appearances notwithstanding - is not going off like a thermonuclear bomb. The limiting factor in the rate at which the Sun produces energy is the speed of weak interactions (the second weakest of the four fundamental forces). Weak interactions are closely linked to the production of neutrinos - which explains why astrophysicists have been so keen to study solar neutrinos - and hence the celebrated Homestake Mine experiment with its even more famous 'wrong answer'
- a wrong answer that has since been explained away by the currently-held theory of neutrino 'flavour oscillations'.But, anyway, the Sun is indeed spewing out neutrinos by the godzillion, just that they're changing their shape as they whizz through space. But this represents a relatively low rate of energy production, hence the Sun's long lifetime.
Astrophysics can have its moments...
- Location
- Next door to Mr Benn at No 54
Pete said:
I thought it was Applied Mathematics that had moments?
Arch said:
well if you want to be completely pedantic, like you clearly do
, no-one PRODUCES energy. It's impossible to actually produce energy out of nowhere. People don't, the sun doesn't. People CONVERT energy in the form of chemical energy in food to energy in other forms, such as heat energy, kinetic energy, and the sun CONVERTS energy from chemical energy in the form of hydrogen to heat and light energy (and probably some sound aswell), but it converts significantly MORE per cubic metre than a human does per cubic metre! Don't seriously think i'll take you seriously if you tell me humans convert more, 'cos whereever you've read that it's total guff, it doesn't make the remotest amount of sense. It either doesn't actually say what it purports to mean, or else it's just a fabrication.
