Date: Thu Jul 26 08:46:14 2007

Author: Richard Heckathorn

Subject: Re: Collisions, Automobile, Absence of Physicists

Post:
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Greetings,

=20

Speaking of ABS problems, I was driving my car one
day when I pressed on the brakes and.they would
not push down and I had none. I pumped them and
they finally worked. I called my son, an auto
mechanic. He asked me to come to the shop where he
took out the ABS fuse. I don't remember what he
said was wrong but he had it happen to customers
and him on customer cars a number of times. I
don't remember what he said it would take to fix
it. I drove the car that way for a couple of years
before I got rid of it.=20

=20

Dick

Helping teachers who facilitate, motivating
students who learn.

Dick Heckathorn 14665 Pawnee Trail Middleburg
Hts, OH 44130 440-826-0834

www.cvcaroyals.org/~rheckathorn/

Adjunct Physics Teacher - Baldwin Wallace College

Physics is learning how to communicate with ones
environment so that it will talk back.

=20

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu
[mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of
Paul Nord
Sent: Wednesday, July 25, 2007 1:34 PM
To: tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] Collisions, Automobile,
Absence of Physicists

=20

This forensic physicist told us that the marks are
very faint. You get some light dust left behind.
If they're not photographed right away, he said
there's very little trace left. Any rain, washes
them away right away. Even some traffic on the
road will blow them off.

=20

If you could pull the ABS fuse, it might be a fun
demonstration day activity. Thought it doesn't
sound incredibly safe.

=20

Paul

=20

=20

On Jul 25, 2007, at 12:14 PM, Richard Heckathorn
wrote:





Greetings,

=20

Have you had a panic stop and then looked at the
skid marks? I have not. Yet as I observe the road,
I do not see as many car skid marks as I use to.

=20

I know you can disable ABS. Wonder what the marks
would be, not be if I did a panic stop with ABS on
and off?

=20

Dick

=20

=20

Helping teachers who facilitate, motivating
students who learn.

Dick Heckathorn 14665 Pawnee Trail Middleburg
Hts, OH 44130 440-826-0834

www.cvcaroyals.org/~rheckathorn/

Adjunct Physics Teacher - Baldwin Wallace College

Physics is learning how to communicate with ones
environment so that it will talk back.

=20

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu
[mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of
Paul Nord
Sent: Wednesday, July 25, 2007 12:43 PM
To: tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] Collisions, Automobile,
Absence of Physicists

=20

My understanding is that ABS systems barely leave
a skid mark.

=20

The skid mark really requires the tire to scrape
against the road. But ABS will prevent you from
locking the brakes.

=20

I can attest to the lack of tire squealing noise
in an emergency breaking situation.

=20

Paul

=20

=20

On Jul 25, 2007, at 10:42 AM, Gordon Shepherd
wrote:

=20

A table full of traffic officers confirmed to me
that the coefficient of friction as applied to
skid marks went "out the window" with the ABS
brake systems. Judgement based on damage caused
has to be used most often these days.
Gordon Shepherd

Bill Norwood wrote:

Hi tappers,
=20
My theory is that "forensic physics; accident
reconstruction" will never be
a field in which many physicists will ever be able
to make much money, and
that is because there is much more money to the
economic fallout from
carnage. Our bottom line, as in the Jungle, is to
feed as many beings as
possible, not to save lives. Just index through
the industries that thrive.
=20
How much "instructional traffic" have you seen
with the (now older)
instructional movie, "The Physics of Automobile
Collisions?
=20
After many years of seeing too many dead people
along the highways, thrown
from car wrecks etc., I finally gave my car away
to charity two years ago -
and to think, I could have killed someone, and
almost did a few times, and
had that to live with for the rest of my life.
=20
Bill Norwood
=20
=20
-----Original Message-----
From:
tap-l-owner@lists.ncsu.edu [

mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Paul Nord
Sent: Tuesday, July 24, 2007 12:00 PM
To:
tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] Billiard Ball friction
=20
Gary,
=20
Sometimes the answer you need might assume the
best-possible friction.
=20
Had a good talk here a couple of years ago by
someone who does =20
forensic physics; accident reconstruction. Showed
some very nice =20
illustrations of skid marks, and calculations of
the forces on each =20
tire when swerving. He went through a dramatic
case. A single-car =20
accident where some kid skidded for a while
through a suburb, swerved =20
off the road, and rolled into a parking lot.
Assume maximum =20
threshold braking... until the point where the
curb sheered off the =20
tires. Give him the benefit of the doubt about
rolling friction, =20
energy loss while crashing through shrubs, the
softness of the grass, =20
and the impact velocity with the parked cars...
and you will =20
calculate that he was going at _least_ 80 MPH when
he hit the =20
brakes. That's the answer the insurance company
needed.
=20
Paul
=20
On Jul 24, 2007, at 9:42 AM, Gary Karshner wrote:
=20
=20

Bernard,
Nice web sights if only the first had
given his students =20
results. Many years ago I had a colleague who was
called as an =20
expert witness in a court case. He need the
coefficient of friction =20
for a leather shoe on a asphalt tile floor. He
made up a tiled =20
board to use as an inclined plane and had the
students in his =20
physics labs measure the coefficients of friction.
The standard =20
deviation of their answers was almost 15% with one
shoe on the same =20
plane. I tell my students any time they see a
coefficient of =20
friction stated to two significant figures don't
believe it. A =20
quick glance at the CRC handbook supports this
although plastic =20
against felt is not listed. The frictional force
as the force =20
normal time some coefficient is not great model at
best. There was =20
an AJP article a few years ago examining this
question.
Sommerfeld's "Mechanics" has a very
concise look at the =20
game of pool from a physicists point of view. He
references =20
Coriolis' 1835 book "Theorie mathematique des
effets du jeu de =20
billard" as his reference.
Gary
=20
Some seemingly simple questions don't have
22/2007 -0700, you wrote:
=20

Why the "reals"? Such a statement: ... high
quality ball and =20
table ... is sufficient to rule out imaginary
ones. Usually and =20
quite clearly, if a discussion involves imaginary
objects the =20
word "model" is used.
=20
bc, sick of the word "real", and suggests a trip
to the local pool =20
hall, as did the class in the following page:
=20
=20

http://artemis.austincollege.edu/acad/physics/lrob
in/Workshop%=20
20Physics%20Projects/group%204.html
=20
p.s. here's a rather good discussion on imaginary
pool:
=20
=20

http://www.gamasutra.com/features/20000516/lander_
pfv.htm
=20
=20
=20
George M. Caplan wrote:
=20
=20

What the coefficient of friction (static and
kinetic, if =20
possible) between a real, high-quality billiard
ball and a real, =20
high quality pool
table?
=20
=20
=20
=20
=20

=20
=20
=20

=20





=20


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Greetings,



Speaking of ABS problems, I was =
driving my
car one day when I pressed on the brakes and…they would not push =
down and
I had none. I pumped them and they finally worked. I called my son, an =
auto
mechanic. He asked me to come to the shop where he took out the ABS =
fuse. I don’t
remember what he said was =
wrong but he had it happen to customers and him on customer =
cars a
number of times. I don’t remember what he said it would take to =
fix it. I
drove the car that way for a couple of years before I got rid of it. =






Dick

Helping teachers =
who
facilitate, motivating students =
who
learn.

Dick
Heckathorn 14665 Pawnee Trail Middleburg Hts, OH
44130 440-826-0834

www.cvcaroyals.org/~rheckathorn/

Adjunct
Physics Teacher - Baldwin Wallace College

Physics
is learning how to communicate with ones environment so that it will =
talk back.





-----Original =
Message-----
From: =
tap-l-owner@lists.ncsu.edu
[mailto:tap-l-owner@lists.ncsu.edu] On Behalf
Of Paul Nord
Sent: Wednesday, July 25, =
2007
1:34 PM
To: =
tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] =
Collisions,
Automobile, Absence of Physicists



This forensic physicist told us that the =
marks are
very faint. You get some light dust left behind. If they're =
not
photographed right away, he said there's very little trace left. =
Any
rain, washes them away right away. Even some traffic on the road =
will
blow them off.









If you could pull the ABS fuse, it might be a =
fun
demonstration day activity. Thought it doesn't =
sound incredibly
safe.











Paul

















On Jul 25, 2007, at 12:14 PM, Richard =
Heckathorn
wrote:









Greetings,







Have you had a panic stop and then looked at the skid marks? =
I have
not. Yet as I observe the road, I do not see as many car skid marks as I =
use
to.







I know you can disable ABS. Wonder what the marks would be, =
not be
if I did a panic stop with ABS on and off?







Dick















Helping teachers =
who
facilitate, motivating students who learn.

Dick Heckathorn 14665 Pawnee
Trail Middleburg Hts, OH 44130 =
440-826-0834

www.cvcaroyals.org/~rheckathorn/

Adjunct Physics Teacher - Baldwin =
Wallace
College

Physics is learning how to =
communicate with
ones environment so that it will talk back.









-----Original Message-----
From:
tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.=
edu]
On Behalf Of Paul =
Nord
Sent:
Wednesday, July 25, 2007 12:43 PM
To: tap-l@lists.ncsu.edu
Cc:
Paul Nord
Subject:
Re: [tap-l] Collisions, Automobile, Absence of =
Physicists







My understanding is that ABS systems barely leave a skid =
mark.













The skid mark really requires the tire to scrape against =
the
road. But ABS will prevent you from locking the =
brakes.















I can attest to the lack of tire squealing noise in an
emergency breaking situation.















Paul

























On Jul 25, 2007, at 10:42 AM, Gordon Shepherd =
wrote:





A table full of traffic officers confirmed to me that the
coefficient of friction as applied to skid marks went "out the
window" with the ABS brake systems. Judgement based on damage =
caused has
to be used most often these days.
Gordon Shepherd

Bill Norwood =
wrote:

Hi =
tappers, <=
pre
style=3D'margin-left:1.0in'>My theory is that "forensic =
physics; accident reconstruction" will never =
bea field in which many physicists =
will ever be able to make much money, andthat is because there is much =
more money to the economic fallout fromcarnage. Our bottom line, as in =
the Jungle, is to feed as many beings aspossible, not to save lives. Just =
index through the industries that thrive. <=
pre
style=3D'margin-left:1.0in'>How much "instructional =
traffic" have you seen with the (now =
older)instructional movie, "The =
Physics of Automobile Collisions? <=
pre
style=3D'margin-left:1.0in'>After many years of seeing too =
many dead people along the highways, =
thrownfrom car wrecks etc., I finally =
gave my car away to charity two years ago =
-and to think, I could have killed =
someone, and almost did a few times, andhad that to live with for the =
rest of my life. <= pre style=3D'margin-left:1.0in'>Bill = Norwood <= pre style=3D'margin-left:1.0in'> <= pre style=3D'margin-left:1.0in'>-----Original = Message-----From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] OnBehalf Of Paul =
NordSent: Tuesday, July 24, 2007 =
12:00 PMTo: tap-l@lists.ncsu.eduCc: Paul = NordSubject: Re: [tap-l] Billiard =
Ball friction <= pre style=3D'margin-left:1.0in'>Gary, <= pre style=3D'margin-left:1.0in'>Sometimes the answer you need = might assume the best-possible friction. <= pre style=3D'margin-left:1.0in'>Had a good talk here a couple of = years ago by someone who does forensic physics; accident =
reconstruction. Showed some very nice =
illustrations of skid marks, and =
calculations of the forces on each tire when swerving. He went =
through a dramatic case. A single-car =
accident where some kid skidded =
for a while through a suburb, swerved =
off the road, and rolled into a =
parking lot. Assume maximum threshold braking... until the =
point where the curb sheered off the =
tires. Give him the benefit =
of the doubt about rolling friction, =
energy loss while crashing =
through shrubs, the softness of the grass, =
and the impact velocity with the =
parked cars... and you will calculate that he was going at =
_least_ 80 MPH when he hit the brakes. That's the answer =
the insurance company needed. <= pre style=3D'margin-left:1.0in'>Paul <= pre style=3D'margin-left:1.0in'>On Jul 24, 2007, at 9:42 AM, Gary = Karshner wrote: <= pre style=3D'margin-left:1.0in'> = Bernard, &n=
bsp; Nice web sights if only the first had given his =
students results. Many years ago I had a =
colleague who was called as an expert witness in a court case. =
He need the coefficient of friction =
for a leather shoe on a asphalt =
tile floor. He made up a tiled board to use as an inclined =
plane and had the students in his physics labs measure the =
coefficients of friction. The standard =
deviation of their answers was =
almost 15% with one shoe on the same =
plane. I tell my students any =
time they see a coefficient of friction stated to two =
significant figures don't believe it. A =
quick glance at the CRC =
handbook supports this although plastic =
against felt is not listed. The =
frictional force as the force normal time some coefficient is =
not great model at best. There was an AJP article a few years ago =
examining this question. &n=
bsp; Sommerfeld's "Mechanics" has a very concise =
look at the game of pool from a physicists =
point of view. He references Coriolis' 1835 book =
"Theorie mathematique des effets du jeu de =
billard" as his =
reference. &n=
bsp; Gary &n=
bsp; Some seemingly simple questions don't =
have 22/2007 -0700, you =
wrote: =


Why the =
"reals"? Such a statement: ... =
high quality ball and table ... is sufficient to rule =
out imaginary ones. Usually and =
quite clearly, if a =
discussion involves imaginary objects the =
word "model" is =
used. bc, sick of the word =
"real", and suggests a trip to the local pool =
hall, as did the class in the =
following page: http://artemis.austincollege.edu/acad/physics/lrobin/Workshop%=
20Physics%20Projects/group%204.h=
tml p.s. here's a rather good =
discussion on imaginary pool: http://www.gamasutra.com/features/20000516/lander_pfv.htm George M. Caplan =
wrote: =


What the coefficient of =
friction (static and kinetic, if possible) between a real, =
high-quality billiard ball and a real, =
high quality =
pooltable? &n=
bsp;



<= pre style=3D'margin-left:1.0in'> <= pre style=3D'margin-left:1.0in'> = ------=_NextPart_000_0044_01C7CF61.667EC5B0--

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