Science & Technology Quiz 2: The one with the catchy title.

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brennan

Argumentative Brit
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Procedures :-
1) A asks a question, the rest will try to answer.
2) A must confirm which answer is correct.
3) Person (say B) with confirmed correct answer then asks the next question.
4) A cannot play again until B's turn is over (to prevent the thread turning into a 2 person spam party).
5) Repeat.
6) If person asking question doesn't login to confirm answers within 72 hrs of his question being posted, any one can ask a new question.
7) If no one can answer question within 72 hrs or can't get the right one, questioner can ask again.
8) Definitely no Net or book searches. The answers would be too easy to find if you were allowed to use Google and the like.
9) If answer has been confirmed and the new questioner hasn't set a question in 72 hours, anyone can ask the new question.
10) You can ask questions on any aspect of science (including the history of science and scientists) but let's try not to resort to 'm=3kg a=2ms-2 please work out F'. Come on, guys. Technology questions are also allowed and encouraged.
11) Mathematics is also allowed, but take heed of rule 10).
Link to thread #1: Cumulative General Science/Technology Quiz

Since nobody else wanted to take the plunge: Here's an intriguing tidbit I picked up during a stellar physics module:

If you took a cubic metre of stellar material, e.g. from the Sun, how much heat would it produce (i.e. generate via fusion)?
 
I don't know (and can't answer anyway since I asked the last question) but could you paste the rules into the OP please, brennan? :) Unless this is going to be a free-for-all :devil:
 
None? If its only a cubic metre, then it wouldn't have critical mass for fusion?

I am wondering if its a trick question. If I recall vaguely correctly, and its been a long, long time, when a stellar mass forms, if it has enough mass greater than a certain limit (cherenkov limit?) then it can collapse and form a star, kicking-off the fusion process. If it has too much, it can form a black-hole. The key is that you haven't given us enough information to determine anything - you've only given us a volume, not a mass. Given that fission is related to mass, then I assume (via occam's razor) that the only answer that can be correct is the simplest one: zero.
 
I didn't mean to literally take it out of the Sun, just take that volume of the Sun theoretically. Basically how much power does it output?
 
Depends where that cubic meter was gathered from. The mass in the outer (?) 95% of the sun doesn't produce any energy, except maybe from the friction of falling into the gravity well.
 
EDIT: 4th time lucky...

This time I get 10 Watts again, from my 4th fag packet estimate.

Solar constant ~ 10^3 W/m^2 at 10^11 m from center.
Radius of sun ~ 10^8 m.
=> Radiation at surface ~ 10^3*(10^11/10^8)^2 = 10^9 W/m^2
W/m^3 ~ 10^9/10^8 ~ 10 W/m^3

So 1m^3 of Sun gives off 10 Watts.
 
The average density of the sun is about 1400 kg/m^3. Assuming you could directly convert all of that to energy (which you can't do), 144 exajoules.

To calc actual figures about the fusion process, I would need to know the density of Hydrogen and Helium in that cube in order to work out the mass defect.
 
Sorry, I missed a day and then forgot about this yesterday. :blush:

Good analysis btw, the actual figure is around a measly 100W, around the same as the human body generates at rest. It's too long since I did it to remember how the calculation goes though, sorry.

Mise next.
 
Yup! Except for the British part. It was never our disease :p


When syphilis was first observed in 1495, each successive nation of sufferers named the scourge after their closest enemies, so that the French called it "the Neapolitan sickness," the Italians "the French sickness," the British "the French pox," and, after 18th century explorers imported the disease to Tahiti, it was inevitably dubbed "the British disease."

:p :p
 
It was a toxic heavy metal, wasn't it? I think the answer is mercury, or a mercury containing chemical. I'm pretty sure it was developed in around the turn of the 20th C., but I can't recall who it was.
 
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