In comp.lang.java.advocacy, Otis Bricker
<obricker@[EMAIL PROTECTED]
>
wrote
on Wed, 18 Jun 2008 15:23:14 -0500
<Xns9AC1A6B39E4ECobrickermydejanewsco@[EMAIL PROTECTED]
>:
> Roedy Green <see_website@[EMAIL PROTECTED]
> wrote in
> news:t4oa54h6a9ojeli3h0sm4a5kh593r9isbu@[EMAIL PROTECTED]
>
>> On Sun, 08 Jun 2008 14:18:30 +0200, Daniele Futtorovic
>><da.futt.news@[EMAIL PROTECTED]
> wrote, quoted or indirectly quoted
>> someone who said :
>>
>>>ot high enough to heat anything,
>>
>> That is a very unscientific statement.
>>
>> Please show your physics before you patronisingly spit at me for even
>> considering the problem. Obviously, the size of the object heated is
>> of considerable im****tance. A shorted dry cell gets plenty hot.
>>
>> To pop a single kernel of corn would take considerably less than the
>> amount of energy needed to convert an equal volume of water to steam.
>>
>> I don't think you can't categorically dismiss the question without a
>> little back of the envelope math. In any case, I get really really
>> annoyed with folks who try to squash curiosity in others. There is
>> nothing wrong with asking questions even when the answers (including
>> the wrong answers) are "obvious" to some.
>>
>> I hope you don't have any kids.
>>
>
> getting a BackOfEnvelope estimate is always a good place to start. But
it
> would help to have better numbers to base this on
>
>> As a ballpark, I will guess you need to va****ise a milligram of water
>> to pop a kernel.
>>
>
> Why this number?
No doubt one can get a rough estimate by looking at the
weight of a 1/4 cup of popcorn, then counting the kernels.
I suspect it's more than a milligram per kernel; that's
ridiculously small. Cold tablets in particular have a
lot more weight than that, even the small ones, which are
a little bigger than a popcorn kernel.
>
>> The latent heat of va****isation is 2260 joules per gram.
>>
>> So I would need roughly 2 joules to pop one kernel.
>>
>
> Assuming all the energy went into a particular milligram of water in the
> the kernal.
Somehow, I for one doubt it. :-)
> The average kernel weighs 140 milligrams and has a 13-14%
> moisture content. So about 18 milligrams of water. This also ignores the
> fat content. Also much of the energy would transfer from the warmed
water
> to the solids of the kernel. It would probably be better to estimate
> temperature increase and increased va**** pressure.
If one has that info handy. I can't say I do.
>
>> A joule is a watt-second.
>>
>> You can get 3 watt cell phone boosters, but most cell phones are about
>> 1 watt according to
>> http://electronics.howstuffworks.com/cell-phone-radiation1.htm
>>
> Actually, most are a good deal below that. They moderate the amount of
> power based on signal strength. And with most output numbers quoted this
> way, you may need to convert to average power from peak power. I'm not
> sure and cannot bother to check.
>
>> If you put three of them together you would have available 3 watts.
>>
>> Presuming all the power went into the heating the kernel, I should be
>> able to pop a kernel within a second.
>>
>
> But the output is roughly omni-directional so only a small fraction of
> that energy would reach the kernel. Or your head. So perhaps 50% would
be
> a better number
One might do something silly like fa****on a metal cup. I'll admit
I wonder what that'll do to the poor handsets' radios, as one is
effectively changing the impedance.
>
>> So I think an experiment is in order to see if this is a hoax, after
>> you check my arithmetic of course.
>>
>>
>
> Or let someone else do it for you.
> http://www.snopes.com/science/cookegg.asp
>
Just as a computational check:
A jumbo egg is required to be at least 29 ounces; even
a small egg needs to be 17. (The actual grading is
somewhat dependent on packaging; I don't know if that's
because they count the weight of the packaging, or what.
http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELDEV3004376
Your mileage may vary in other countries, of course,
and chickens don't have a clue as to grading anyway;
they just lay the silly things.)
Cooking instructions in the microwave are reasonably
easy to obtain; one fried egg on 50% power (550 watts,
presumably, plus or minus -- they don't specify that
or egg size, but one might assume a large) takes about
2-3 minutes:
http://whatscookingamerica.net/Eggs/MicrowaveEggs.htm
That translates into about 66kJ, as a bare minimum,
though one might reasonably ask how much power is wasted
within the microwave chamber and how much of the rest is
intercepted by the egg proper.
Or one can contemplate 3-minute eggs in boiling water.
Assuming an egg is mostly water, and a 17-ounce or
481-gram egg starting out at 10 degrees C and heated
to boiling, one gets 0.481 * 90 * 4186 = 181 kJ,
though this is probably an overestimate. Then again,
http://whatscookingamerica.net/Eggs/PoachEgg.htm
recommends poaching an egg for 3 minutes, though it
suggests a temperature lower than boiling -- 71-82 C,
and starts the eggs at room temperature (about 25C).
That only decreases the requirement to 91kJ-111kJ.
And that's for a *small* egg.
Assuming a setup similar to the one in the Snopes article,
which might intercept 1/8th (as I estimate the setup,
visually speaking) of the radiated power from the phone if
one's lucky (anyone familiar with antennae might quibble
a bit with this; radiation patterns are interesting but
probably more technical than I need to be here), and 5
watts of transmitted power (I base that on old regulations
regarding CB radios but would one really want more than a
few watts next to one's ear?), 65 minutes of "air time"
is nowhere near enough to transmit the requisite amount
of energy, compared to the above microwave instructions;
one only gets 1/8 * 5 * 65 * 60 = 2437.5 J.
Snopes is even more pessimistic, assuming 0.25W per phone.
One would have better luck leaving the eggs out in direct
sunlight; at least that way one might get an intercept of a
few dozen watts. (Of course if one really wants to go that
route a readily-constructible solar oven using aluminum
foil is preferable, to increase the cooking power.
To fry an egg in 2-3 minutes one might need 0.5 m^2 of
gathering area, and of course a nice sunny day.)
All this of course is very good news for those who walk
around with Bluetooth attachments and worry about their
brains being fried thereby. The short answer: don't worry,
unless one sleeps with the thing on continuously for 10
years or so.... ;-)
--
#191, ewill3@[EMAIL PROTECTED]
-- insert random bad yolk here
Is it cheaper to learn Linux, or to hire someone
to fix your Windows problems?
** Posted from http://www.teranews.com
**
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