On 14 Aug, 11:47, wrote:
On Fri, 14 Aug 2009 03:37:33 -0700 (PDT)

Andy wrote:
But turbulence does not heat the air. Turbulent air generally stays at

Any movement of one section of a fluid against another will heat it.
Eg if a propeller blows a load of air backwards that air will eventually
stop moving with respect the rest of the air mass around it. How do you
think the energy is lost? As heat of course.


BUT that is friction (between air molecules and of air molecules with
solid objects) doing the heating not the turbulence itself. 'Bruce'
was claiming that the friction was a minor component of the heating,
but friction is pretty much the only source of heating when airflows
are considered.

David Cantrell gurgled happily, sounding much like
they were saying:

There's the small problem that while I can leave my car unattended on
the street it doesn't get stolen, because it's too heavy to lift and
is easily traceable, while if I were to leave a bike unattended on
the street, it would be. And there's nowhere else to leave it,
because I, like an awful lot of people, live in a small flat.

Have you heard of these things called "locks"?

Funny man. Have you heard of these things called "bolt cutters"?

A lock is sufficient, I am sure, if the bike is left in a busy area
where a naughty fellow would be seen cutting the lock off. It is not
going to be sufficient at 4am on a Monday night on a residential street.

It's odd. I'm sure I recall Duhg regularly claiming that car owners are
fools for leaving cars parked in public, since they were liable to be
stolen - and that that was a reason why people should use bikes instead
of cars...

"David Cantrell" wrote in message
k


[snip] Cars are competitive with trains in terms of journey time for
short journeys of up to roughly 70 miles outside major cities. So at
minimum an electric car needs to be able to go 140 miles (for a return
journey), plus, say, another 20 miles just for a safe margin, at
current speeds without recharging. Otherwise people won't buy them.

Indeed, which is why manufacturers like BMW have been very cautious
about putting cars like the MINI E on sale in the UK.

It seems like pure electric cars have a usable range of less than 100
miles, which means a radius of not much more than 40 miles. Because of
the long recharging times, this is also effectively the daily limit
until there's a dense infrastructure of high power recharging points
(not just a few token recharging points in central London).

It also means that even if someone's typical journeys are within this
range, they will be deterred from buying if they need to do the
occasional longer trip for which public transport isn't a reasonable
option. But with such low mileages, the fixed battery leasing cost will
be far more than any saving achieved by using low-taxed electric power
compared to high-taxed petrol or diesel, and the (probably temporarily)
saving on road tax and congestion charges.

So, the electric car will cost more to use, have a very impractical
range, be tedious to re-charge compared to the occasional trip to a
filling station for a quick fill-up, and less fun to drive, thanks to
the heavy batteries. And that's before we ponder the fire risk from a
quarter of a tonne of Li-ion batteries under the floor -- see this
staged reconstruction of what happens when a far smaller laptop battery
explodes: http://www.youtube.com/watch?v=WeWq6rWzChw

On Fri, 14 Aug 2009 04:10:01 -0700 (PDT)
Andy wrote:
solid objects) doing the heating not the turbulence itself. 'Bruce'
was claiming that the friction was a minor component of the heating,

Ah ok , didn't realise thats what he was saying. That kind of stupid
argument is par for the course with Bruce (or whatever his real name is).

B2003

On Fri, 14 Aug 2009 03:37:33 -0700 (PDT), Andy
wrote:

But turbulence does not heat the air. Turbulent air generally stays at
the same temperature as the still air that was in position before.
Heat is all in the internal vibrations of the air molecules, not in
the bulk movement.


Utter nonsense. Go to the back of the class!

On Fri, 14 Aug 2009 12:21:12 +0100
"Recliner" wrote:
the heavy batteries. And that's before we ponder the fire risk from a
quarter of a tonne of Li-ion batteries under the floor -- see this
staged reconstruction of what happens when a far smaller laptop battery
explodes: http://www.youtube.com/watch?v=WeWq6rWzChw

Mind you , to flip that on its head imagine the howls of fear and indignation
there would be if we all currently drove electric cars and someone was now
proposing to sell a car that ran with up to 50Kg of a highly flammable and
potentially explosive hydrocarbon liquid sitting in a tank behind the back
seat?

B2003

wrote in message
On Fri, 14 Aug 2009 12:21:12 +0100
"Recliner" wrote:
the heavy batteries. And that's before we ponder the fire risk from a
quarter of a tonne of Li-ion batteries under the floor -- see this
staged reconstruction of what happens when a far smaller laptop
battery explodes: http://www.youtube.com/watch?v=WeWq6rWzChw

Mind you , to flip that on its head imagine the howls of fear and
indignation there would be if we all currently drove electric cars
and someone was now proposing to sell a car that ran with up to 50Kg
of a highly flammable and potentially explosive hydrocarbon liquid
sitting in a tank behind the back seat?

At least petrol doesn't spontaneously combust or overheat, and the fuel
tank is a lot smaller, lighter and easier to protect.

On Fri, 14 Aug 2009, David Cantrell wrote:

On Thu, Aug 13, 2009 at 06:33:07PM +0100, Tom Anderson wrote:
On Thu, 13 Aug 2009, David Cantrell wrote:
There's the small problem that while I can leave my car unattended on
the street it doesn't get stolen, because it's too heavy to lift and is
easily traceable, while if I were to leave a bike unattended on the
street, it would be. And there's nowhere else to leave it, because I,
like an awful lot of people, live in a small flat.
Have you heard of these things called "locks"?

Funny man. Have you heard of these things called "bolt cutters"?

A lock is sufficient, I am sure, if the bike is left in a busy area
where a naughty fellow would be seen cutting the lock off. It is not
going to be sufficient at 4am on a Monday night on a residential street.

Presumably, you speak from experience, or have statistics which make you
think this? It's just that i've left my bike overnight in all sorts of
places, quiet and otherwise, and it hasn't been nicked, and it sounds to
me a little bit like you might be talking out of your arse.

tom

--
We refuse to believe that there is no man out there on this planet that is
able to eyaculate a yogurt on a daily bases. -- the5litresexperiment.com

On Thu, 13 Aug 2009, Richard J. wrote:

Tom Anderson wrote on 13 August 2009 18:32:19 ...
On Thu, 13 Aug 2009, Basil Jet wrote:

Bruce wrote:
On Thu, 13 Aug 2009 12:22:13 +0100, "Recliner"
wrote:
The ever-reliable Wiki source says that the 2009 stock is 2.68m wide
and the 1973 stock 2.629, so the 2009 stock is apparently 5cm or 2"
wider. It also says that, "Unlike the 1967 Tube Stock, the trains
are built 40 millimetres (1.6 in) wider to take advantage of the
Victoria line's slightly larger than normal loading gauge compared
to the other deep level tube lines."

Ironically, one of the reasons why the Victoria Line tunnel was built
to a larger diameter was to reduce air resistance. ;-)

It's not unreasonable to build the first stock for the line small to
reduce air resistance, and then build subsequent stock large to push the
hot air along.

If the air's hot, then building the train bigger means there's less of it
surrounding the train, so the train won't get heated up by it so much.

On the contrary, the bigger train has more surface area so is in contact
with a greater area of hot air. Also, the smaller gap between train and
tunnel will increase the frictional heating effect.

My attempt at humour was evidently not quite obvious enough. Apologies.

tom

--
We refuse to believe that there is no man out there on this planet that is
able to eyaculate a yogurt on a daily bases. -- the5litresexperiment.com

On 14 Aug, 12:35, Bruce wrote:
On Fri, 14 Aug 2009 03:37:33 -0700 (PDT), Andy
wrote:



But turbulence does not heat the air. Turbulent air generally stays at
the same temperature as the still air that was in position before.
Heat is all in the internal vibrations of the air molecules, not in
the bulk movement.

Utter nonsense. *Go to the back of the class!

Really? Can you explain how turbulent air gets hotter without
friction? I suggest that you go and read up on fluid dynamics and try
and learn something.