iandol on thu 10 may 01
Dear Brian,
Change "Pseudo" to "Fictitious". It is imagined to be the force within =
the string which ties an object to the centre of rotation. Your =
Professor of Physics was right as far as I am concerned.
Friction causes slip to flow in straight lines until they hit the edge, =
then they turn the corner and fly off at a tangent.
Best regards,
Ivor
vince pitelka on fri 11 may 01
Ivor said:
"Friction causes slip to flow in straight lines until they hit the edge,
then they turn the corner and fly off at a tangent."
Okay, Ivor, I might catch hell for this, but the above seems completely
ridiculous. If the slip builds up momentum flying out from the center of
the wheel in a straight line, then it is not going to be turning any corn=
ers
when it gets to the rim. And I cannot see how friction has anything to d=
o
with it at all. Keep in mind that my opinions here are unencumbered by
theoretical physics. I only know what I have seen.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Larry Phillips on sat 12 may 01
vince pitelka wrote:
>
> Ivor said:
> "Friction causes slip to flow in straight lines until they hit the edge=
,
> then they turn the corner and fly off at a tangent."
>
> Okay, Ivor, I might catch hell for this, but the above seems completely
> ridiculous. If the slip builds up momentum flying out from the center =
of
> the wheel in a straight line, then it is not going to be turning any co=
rners
> when it gets to the rim.
The slip, before it leaves the wheel, is not moving in a straight line,
except relative to the wheel. It is moving in a spiral, relative to your
frame of reference, which is not on the wheel. Once it leave the wheel,
it no longer moves in a spiral, but rather, in a straight line, tangent
to the edge of the wheel.
Seen from the perspective of your normal throwing position, slowed down
enough, the spiral track stops being spiral and becomes a straight line
at the edge of the wheel.
Seen from the perspective of an eyeball at the center of the wheel, the
slip goes straight out away from the center, and when it reached the
edge of the wheel, keeps moving somewhat straight out, until it starts
falling behind (no longer attached to the wheel, so not being pulled in
the radial direction).
So, what you see is different from each vantage point. The little trails
of slip you see are tracks showing you the path from the wheel's point
of view, and show none of the radial component at all.
> Keep in mind that my opinions here are unencumbered by theoretical phy=
sics.
I hope the above serves to point out the reality of the phenomenon
without miring you in the theoretical. You really don't need to be a
physicist to see what's happening; you just need to consider more than
your usual vantage point.
> I only know what I have seen.
It's not always enough for complete understanding.
--
Procrastinate now!
http://24.113.44.106/larry/
Snail Scott on sat 12 may 01
At 09:00 PM 5/11/01 -0500, you wrote:
>Ivor said:
>"Friction causes slip to flow in straight lines until they hit the edge,
>then they turn the corner and fly off at a tangent."
>
>Okay, Ivor, I might catch hell for this, but the above seems completely
>ridiculous. If the slip builds up momentum flying out from the center o=
f
>the wheel in a straight line, then it is not going to be turning any cor=
ners
>when it gets to the rim. And I cannot see how friction has anything to =
do
>with it at all. Keep in mind that my opinions here are unencumbered by
>theoretical physics. I only know what I have seen.
>Best wishes -
>- Vince
The slip is only making lines directly outward relative
to the stationary wheel, as you look at it stopped.
While the wheel is moving, the slip-drips are moving
in a circle, too, at the same rate as the wheelhead.
(It's the tangent motion that allows the slip to move
outward. Draw a short line segment, tangent to the edge
of your pot on the wheelhead. It will end further out
than it began, and also to one side, yes? But if that
line were a slip-drip, the wheel would be moving with
it, and the lateral component of that line would be
'eaten up'. The only visible effect would be the outward
component of the motion.
When they reach the edge, the drips no longer have the
continuous accompaniment from the wheel, and fly into
the air tangent to the wheel edge. They were moving
tangent all along, but the wheel moved with them,
making the 'trails' look radial.
-Snail
Rick Monteverde on sat 12 may 01
Folks -
Just remember that in your arguments that the centrifugal force is
not real, you're sweeping gravity under the same rug. In the
relavitivistic view, gravitational 'force' can be no more real than a
centrifugal 'force'. A 'warp' in space is just another way of putting
a tweak in your reference frame, similar to a spinning bat. The slip
ends up on your apron either way.
- Rick Monteverde
Honolulu, HI
vince pitelka on sat 12 may 01
> The slip, before it leaves the wheel, is not moving in a straight line,
> except relative to the wheel. It is moving in a spiral, relative to you=
r
> frame of reference, which is not on the wheel. Once it leave the wheel,
> it no longer moves in a spiral, but rather, in a straight line, tangent
> to the edge of the wheel.
Okay, Larry and Ivor, I think I get it now. While the slip is moving
straight out from the center of the wheel head, the wheel head is rotatin=
g
quickly, so in fact the slip is moving in space in a spiral. When it lea=
ves
the wheelhead it continues on that spiral, or in a straight-line extensio=
n
of that sprial, generally on a tangent to the edge of the wheelhead. Thi=
s
makes sense. I was just looking for something that made sense in terms o=
f
what I have witnessed. But the slip does not turn any corners. Okay?
I have a headache. I am certain that I can attribute it to the centrifug=
al
force of the Earth spinning through the Galaxy.
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
iandol on sun 13 may 01
Dear Vince,
As a kid I lived at the end of a bus route. Given a road free from on =
coming traffic, the Driver would not stop allowing passengers to alight =
from the bus but would swing round in a wide semi circle. We kids would =
get onto the open platform and feel the pull start as the bus turned. We =
would bale out. Now the pull of our bodies against our arm was in line =
with the radius of rotation just before we released our grip, but we did =
not move along that line. No,we flew off at a tangent, following the =
direction of the bus but departing from it at an angle.
Although the pathway of the slip appears to be in straight lines, I =
believe the motion of each particle of slip is in the form of a spiral =
pathway. This would be visible if you were to make cinematic images and =
run them in slow motion and plot it's movement. The straight line is the =
"Apparent" motion.=20
There are a lot of interesting things in our World. I agree with you =
wholeheartedly. Some of them seem extremely ridiculous.
Good to get your message.
Best regards,
Ivor=20
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