>>> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
>>> resistor when the current is 1 ampere.
>>
>> And here I was thinking that the heat produced depends on the
>> characteristics of the material, not just the current...
> 
> In a sense that's true - but the material characteristics influence the 
> resistance /exactly/ the same way as the heat produced ;-)

Hmm, interesting.

> The thing with muscles is, they never actually hold something still 
> unless they're totally slack. When they're contracted, they actually 
> twitch at a high frequency

Individual fibers twitch, yes. A single "muscle" contains rather a lot 
of individual fibers though, all twitching in a coordinated pattern. The 
net result is more or less contant tension.

I'm told this is why when you try to lift something too heavy, you start 
shaking. You run out of fibers to twitch.

(Related... I'm told that if *all* the fibers were to twitch at once, 
the muscle would probably tear itself from its attachment points. Which 
perhaps explains why people undergoing convulsions sometimes display 
superhuman strength.)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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