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>> A door isn't nearly as heavy as a person.
>
> Some of the ones we had offshore weighed half a ton.
Short or long?
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> Mass rises as the cube of size, but muscle power rises as the square of
> size.
I would have thought the strength of a muscle depends on its volume, why do
you say is rises with the square of size?
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scott wrote:
>> Mass rises as the cube of size, but muscle power rises as the square
>> of size.
>
> I would have thought the strength of a muscle depends on its volume, why
> do you say is rises with the square of size?
Muscle power is [apparently] proportional to cross-section area, not volume.
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>>> Mass rises as the cube of size, but muscle power rises as the square of
>>> size.
>>
>> I would have thought the strength of a muscle depends on its volume, why
>> do you say is rises with the square of size?
>
> Muscle power is [apparently] proportional to cross-section area, not
> volume.
I guess that makes sense if you assume each cell in the muscle fibre can
only exert a certain force, a chain of them can still only exert that same
force no matter how long it is. It's having more fibres in parallel that
help to increase the force.
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>> Muscle power is [apparently] proportional to cross-section area, not
>> volume.
>
> I guess that makes sense if you assume each cell in the muscle fibre can
> only exert a certain force, a chain of them can still only exert that
> same force no matter how long it is. It's having more fibres in
> parallel that help to increase the force.
Precisely.
Also of note is that [apparently] if all the fibers were to contract
simultaneously, the muscle would be ripped from the bone (assuming
there's any load on it). Apparently the fibers are actually programmed
to twitch a few at a time, so that they have time to recover between
contractions, while the muscle as a whole maintains constant force.
You know how when you try to lift something too heavy and you start
shaking? That's apparently because there aren't enough fibers fiting at
once...
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Invisible a écrit :
>>> Not obese, no. Also not fit. My arms contain very little muscle, and
>>> attempting to lift 100 Kg using only my arms operating in an unusual
>>
>> Then don't lift your body; push the earth down.
>
> Mass of the Earth = 5.9742 × 10^24 Kg o_O
That's nothing, but the guys at the antipods are giving you some trouble
(as they push down too... to your side!)
--
A: Because it messes up the order in which people normally read text.<br/>
Q: Why is it such a bad thing?<br/>
A: Top-posting.<br/>
Q: What is the most annoying thing on usenet and in e-mail?
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Invisible wrote:
>>> A door isn't nearly as heavy as a person.
>>
>> Some of the ones we had offshore weighed half a ton.
>
> Short or long?
About half a ton.
--
Best Regards,
Stephen
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On 2/9/2010 9:49 AM, Invisible wrote:
>>> I meant more that I wouldn't have expected to be able to just
>>> completely disregard 3/4 the weight of the object just because I'm
>>> only looking at one wheel.
>>
>> Why not? Try doing some one-handed push-ups and see if they are not
>> harder to do than two-handed ones.
>
> When I become able to do two-handed push-ups, I'll let you know. ;-)
>
>>>>> So... what the hell is the thickness of a tin can then?
>>>> 0.2 mm or thereabouts.
>>>
>>> ...my God. You can make metal that thin?? o_O
>>
>> Surely you are joking.
>>
>> http://en.wikipedia.org/wiki/Aluminium_foil
>
> Damn. I thought that stuff was plastic with a metal-powder coating...
You ever try to stand on an empty coke can?
Just set it on level ground and place your foot on it. Then gently
shift all your weight to that foot without losing you balance. The can
should be able to hold you up. It might take a few tries.
Then when on the can, tap the side with your other foot. The can will
flatten nicely.
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"Invisible" <voi### [at] dev null> wrote in message
news:4b728aed$1@news.povray.org...
> >> Not obese, no. Also not fit. My arms contain very little muscle, and
> >> attempting to lift 100 Kg using only my arms operating in an unusual
> > Then don't lift your body; push the earth down.
Makes failure feel a little better, no?
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Invisible wrote:
> Just how strong is steel? I mean, obviously it varies by type, but how
> much load can you typically put on steel without bending/shattering it?
Strong enough to hold up hundreds of floors above it when used in buildings.
I think a piddly little car won't give it too much trouble ;)
...Chambers
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