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>>> Why do overhead cables never flap around in the wind?
>>
>> Actually they do, it's just it's usually very fast and very low
>> amplitude flapping. Imagine holding out a stretched violin string in
>> the wind, it's not really going to flap is it?
>
> Indeed, in strong wind you can actually hear such cables "sing".
I don't know about that, but I *do* know that there's a particular
petrol station I sometimes go to, situated under a ****ing huge set of
pylons. As soon as you get out of the car, all you can hear is an
unearthly crackling sound... I can't describe it, but it's really
quite... worrying.
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Invisible wrote:
> I don't know about that, but I *do* know that there's a particular
> petrol station I sometimes go to, situated under a ****ing huge set of
> pylons. As soon as you get out of the car, all you can hear is an
> unearthly crackling sound... I can't describe it, but it's really
> quite... worrying.
Haha... There's a park near where I live that was basically turned into
a park to make use of land that would otherwise be unusable due to the
power lines. 2 sets, one (I'm guessing, here) a 100kV and the other at
least 250kV (I can only tell one caries a lot more power, one has twin
lines for each phase)
Standing under the twin-line set is creepy as hell. They crackle and
buzz quite audibly. The other lines, are very quiet, they don't make a
sound.
--
~Mike
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> Standing under the twin-line set is creepy as hell. They crackle and
> buzz quite audibly. The other lines, are very quiet, they don't make a
> sound.
Mmm. Petrol station. No naked flames. Switch off engine. No mobile
phones. Bzzzzzzzzzzz.
That can't be good(tm)!
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scott wrote:
>> Did mushrooms evolve to be poisonous because that's advantageous
>> somehow? Or do they just happen to be poisonous to animals because of
>> their unusual chemistry?
>
> Both.
One thing I haven't figured out is why poisonous prey animals (frogs,
butterflies, etc) wind up being brightly colored.
If you're trying to avoid being eaten, it would seem that being hard to see
is a benefit whether you're poisonous or not.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] san rrcom> wrote:
> One thing I haven't figured out is why poisonous prey animals (frogs,
> butterflies, etc) wind up being brightly colored.
AFAIK the bright colors work as a warning signal. Predators learn to
distinguish the poisonous prey by their color.
It would make little sense to just have poison but otherwise look edible.
Both predator and prey get killed. With a warning color both live.
(By this logic it would follow that some species mimic the color of
poisonous species. I wonder if there are examples of this.)
--
- Warp
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scott wrote:
> Anyway, take 200 metres of this stuff (which I make weighs 10 tons):
> http://www.csunitec.com/saws/new-river-band-saw.html
Cool. It doesn't really look that big from the ground, does it?
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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scott wrote:
>> It feels like everybody is writing like power cables were bare metal
>> wires
>> with nothing covering them.
>
> That's how they are actually:
Phone lines used to be bare wire too, and you can sometimes see that (at
least in the USA) running next to train tracks (it tends to look greenish).
Of course, when they invented ways to insulate the wires, they could start
bundling them and/or running them underground.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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>> One thing I haven't figured out is why poisonous prey animals (frogs,
>> butterflies, etc) wind up being brightly colored.
>
> AFAIK the bright colors work as a warning signal. Predators learn to
> distinguish the poisonous prey by their color.
>
> It would make little sense to just have poison but otherwise look edible.
> Both predator and prey get killed. With a warning color both live.
>
> (By this logic it would follow that some species mimic the color of
> poisonous species. I wonder if there are examples of this.)
Hoverflies look very like wasps, but have no venom.
False nettles look like stinging nettles, but lack a sting.
I couldn't give you a name, but I'm pretty sure there are snakes which
are harmless yet mimic deadly ones...
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On Thu, 03 Sep 2009 15:43:01 +0100, Invisible <voi### [at] devnull> wrote:
>> Standing under the twin-line set is creepy as hell. They crackle and
>> buzz quite audibly. The other lines, are very quiet, they don't make a
>> sound.
>
>Mmm. Petrol station. No naked flames. Switch off engine. No mobile
>phones. Bzzzzzzzzzzz.
>
>That can't be good(tm)!
Actually it is quite hard to ignite petrol from a petrol pump with a naked
flame.
Besides having a LEL (Lower Explosive Limit) petrol has an Upper Explosive Limit
(UEL) where above that level the gas/air mixture is too rich to burn. In the
open air the gas/air mixture goes from too rich to too leen very quickly. I once
saw a petrol pump attendant put a lit cigarette into the mouth of a full petrol
tank.
I would not do it myself, though. ;)
--
Regards
Stephen
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On Thu, 03 Sep 2009 09:23:03 +0100, Invisible wrote:
> Each episode
How many (and which ones) did you watch?
Jim
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