ISIS getting dropped?

On Mon, 4 Jul 2005 14:14:34 -0800, "Andrew Lee"
whatsupandrewathotmaildotcom wrote:

Carl, have fun with these:
http://www.cyclingnews.com/photos/20...ur053/BOONEN22

http://www.cyclingnews.com/photos/20...ur053/BOONEN59

Dear Andrew,

I like 'em--thanks.

In the first picture, they're mostly upright, with the
largest tilt of a visible rider being maybe 7-8 degrees for
the rider on our far right (the picture is tilted a little
or the camera is off-center, judging by the road stripes):

http://www.cyclingnews.com/photos/20...ur053/BOONEN22

McEwen is using Grady for a pillow, and I have no idea what
the physics involved there would be.

There's a tilted wheel visible between them, but I think
that the rider's helmet is just visible above them--and he's
turning, judging by how he and his bike appear to be tilted
well past the contact patch to our left.

It's interesting how so many riders apparently sprinting for
the finish are basically upright, but maybe it was just luck
and a moment later some of them tilted to fascinating
angles.

In the second picture, they're still mostly upright:

http://www.cyclingnews.com/photos/20...ur053/BOONEN59

On our far left, the rider in blue is tilted, but obviously
turning, with his body and bike well to our left, past his
contact patch. The yellow rider on the left is tilted about
10 degrees, sprinting fashion rather than turning (again,
the angle makes it look a little more like 12 degrees or
so).

Here, to be fair, the riders are probably relaxing and not
throwing their bikes as much from side to side, but it's
still interesting how upright they are.

Thanks again.

Carl Fogel

In article ,
Jim Smith wrote:

[...]

I kid. I kid.

Heh, I kind of figured with the "hurting america" bit. (:

But, the language was getting more than a little tortured. Phrases
like "inertia accelerating" don't really have any meaning. Then there
was stuff like:

"OTOH, stopping and reaccelerating are two cases where there's a
mismatch. When stopping the force of your brakes' drag exceeds
the force exerted by your momentum decelerating. When taking off
again the force of your pedaling exceeds the force created by your
inertia accelerating. Both actions, because of the unequal forces
involved, require work."


You may indeed have a grasp of the relevant physics, but it isn't
apparant from reading the previous posts. I'm not sure what you mean
by "momentum decelerating," but if we exclude secondary effects, the
force of the brakes drag is exactly equal to the time rate of change
of the momentum, that is just another way of staing Newtons 2nd law:
F=mA, same goes for the case of accelerating from a stop. There are
at least a couple ways to look at why work has to be done to slow the
bike to a stop or to accelerate from a stop. One is that the force is
acting through a distance, another is that that the kinetic energey of
the bicycle is changing. I really can't tell what you were trying to
get at with the mismatched forces thing.

Yeah, I have a pretty bad habit of mangling the hell out of language.
I blame a former existence as a (bad) poet for that one. By stuff like
"momentum decelerating" I meant more along the lines of "the force
needed to change the momentum." Or, with mathematical terms, F=delta p.
I use a physics model that all forces appear in opposed pairs that
may or may not be equal in magnitude, so that's where my comments about
"unbalanced forces" come in. For example, normal force vs. gravity,
both are equal if you're standing still, but if normal force isn't high
enough you sink into the ground. Likewise, riding forward there's a
drag force against you, and your momentum (or rather, F=dp) and pedaling
pushing with you. I like to consider both so that you've got some sort
of force vector available with a name on it to explain how someone can
go over the handlebars.
It's also handy to talk about force balance when working with things
like hydraulics since that's what will determine working pressures. And
I've had a bunch of experience with hydraulics. But I haven't touched
the math at all in about seven years now, so that could be part of why
my brain was mutilating the terminology.

--
B.B. --I am not a goat! thegoat4 at airmail dot net
http://web2.airmail.net/thegoat4/

wrote:
McEwen is using Grady for a pillow, and I have no idea what
the physics involved there would be.

From Wednesday's L'Equipe:
http://anonymous.coward.free.fr/rbr/matelas.jpg

On Fri, 8 Jul 2005 11:08:40 +0200, "Robert Chung"
wrote:

wrote:
McEwen is using Grady for a pillow, and I have no idea what
the physics involved there would be.

From Wednesday's L'Equipe:
http://anonymous.coward.free.fr/rbr/matelas.jpg


Dear Robert,

I like it--presumably the winner slept on a stiff yet
compliant mattress, while the rider nodding off spent a
stressful night on a mattress whose springs had not been
properly stress-relieved.

Carl Fogel