🚀 go-pugleaf

Mark B. wrote:

> Mike Sweeney wrote:
>
> > Coefficient of friction is the ratio of the force necessary to slide
> > an object at uniform speed on a particular surface to the pressure of
> > the object against that surface.  --Traffic Accident Investigators
> > Manual for Police, Northwestern University Traffic Institute.
>
> Nice try, Mike.  Too bad it's wrong.  399.99% DEAD FUCKING WRONG!
>
> 1. Coefficient of friction is a ratio of *forces*;  it is NOT a
>    ratio of force to pressure.  (You can check that in any basic
>    physics or mechanical engineering text / reference manual.)
>
> 2. Pressure is *NOT* force.  You CANNOT bench-press 150 psi.
>

No, actually, from reading the text, it appears that they use "pressure" to
mean weight.

Example reads:

If a wheel presses down on the road with a force of 1000 lbs. and the road
produces a horizontal force or drag on that wheel of 500 lbs., the drag
factor is 500/1000=0.50.


> 3. Force is *NOT* pressure.  You CANNOT inflate your tires with
>    a 30 lb weight (not even if you're a NW.U-certified dumbell.)
>

Some of the people who contributed to this field spent a hell of a lot more
time in "engineering school" than you did.

> 4. Even ignoring the pressure stupidity, the definition applies
>    ONLY to the (increasingly rare) situation where the tires are
>    skidding along the road in a locked-up stop -- although this
>    situation is *IMPOSSIBLE* to achieve with *most* of the cars
>    being sold today.  Thus, sliding c.o.f. is ALWAYS_DEAD_WRONG
>    with *MOST* new cars, and MOSTLY_DEAD_WRONG with *ALL* others.
>

No.  With ABS, you can tell where the maximum braking begins because of the
little choppy, light skids someone else mentioned in here.  You can still
get a total stopping distance.  Then, using some test stops and math you
can work backward to the speed in this case too.  I am still looking for
the article I read on this, but cannot yet locate it.

> It would make more sense to publish the sliding c.o.f. of glass --
> at least a car *MIGHT* overturn and skid to a stop on its sunroof.
>
> The dean and faculty of Northwestern U's Traffic Institute (along
> with all their friends, blood relatives, and casual acquaintences)
> should be skinned alive, tarred and feathered, burned at the stake,
> fed to the lions -- and *then* summarily executed (or condemned to
> drive forever behind a 55mph LLB -- with no possibility of parole.)
>
> > Drag Factor -- the amount of drag that a surface puts on a tire
> > (tires) on a wheel compared to the weight on that wheel.
>
> A truly *pathetic* statement, obviously written by an illiterate,
> innumerate TURBO-moron who wouldn't recognize a clear definition
> (or an English sentence) if it bit him in the ass.
>

Actually, it was probably written so that us "non-engineering" people could
read it, since the rest of you are so damn smart we pale in comparison.

> If you disagree, I *dare* you to explain the difference between
> "drag factor" and c.o.f -- based *ONLY* on the text of the above
> Traffic Institute scatoglyphs.
>
> > ABS lets the brakes lock, then immediately releases them for a
> > fraction of a second, then begins to lock them again.  For this
> > reason, most ABS vehicles, under pedal-to-the-floor braking can
> > be heard to squeal almost as loud as regular vehicles,
>
> Applying for a position on the Traffic Institute faculty, Mike?
> Your English prose needs some work -- it's far too clear -- but
> your technical accuracy is *easily* down to their standards.
>
> Please treat us to a (partial) list of those "most ABS vehicles"
> you've driven in the last 5-10 years.  I found your description
> kinda surprising -- because *none* of the ABS-equipped cars I've
> tried (so far) could even remotely imitate the locked-wheel skid
> of a "regular vehicle".  Of course, you're much more experienced
> with ABS than I am -- seein' as how you're intimately familiar
> with "most ABS vehicles".
>

Mine does jackass.  The last two Caprices I drove did.  The pickup truck
with rear-wheel ABS did.  I have the occasion to be stuck in heavy traffic
often, and most of the ABS vehicles I see (you can tell because they leave
almost no skidmarks) do when the brakes are applied to their fullest.

> I've only had ABS on my daily-driver for 10 years/350,000 miles,
> so I haven't driven anything even close to "most ABS vehicles".
> Including rentals in the USA and Europe, I prolly haven't tried
> more than 30-40 different ABS-equipped models.  OTOH, it *does*
> seem kinda strange that *none* of my 30-40 samples even remotely
> resembled *most* of the *thousands* that you've tested.
>

The "thousands" that I have "tested" actually were ones tested by
automotive mags and other individuals.  Perhaps there are some they
neglected to mention, but the indication was that there will be light,
intermittent marks.

> > and will often leave light skidmarks.  Since this is possible,
> > the difference between that and a vehicle without ABS is less
> > than you might think.
>
> Attaboy, Mike!  *NOW* you're gettin' the hang of it -- you've
> succeeded in bringing the fog-factor up to Traffic Institute
> levels.  Even with RADAR, nobody will crack through the smoke
> screen obscuring the target of that "Since this is possible"
> reference.                                 ^^^^
>
> BTW, it's really comforting to have you figurin' out 'zactly
> what it is that I *might* think,    ...fuck you very much.
>

Congratulations.  You have succeeded in making the killfile.  I had hoped
to post some of the stuff EF was referring to in order to make it easier to
understand.  I tried to explain that I was not a student of this stuff, but
that I did manage a 4.0 in physics.  You just can't seem to debate and
leave the personal stuff out of it.  Goodbye Mr.
I-Have-An-Engineering-Degree.

>
>
> > Also you would have to understand that large variances in skid
> > resistance (drag factor) are equal to much smaller variances in
> > speed.
>
> Well said, Mike -- but you left out one minor detail.  Before
> anyone can hope to grock The Sweeney Effect, they really should
> plan on a full frontal lobotomy followed by complete amputation
> of all fingers and toes.  It's nearly impossible for folks who
> can think (or count past one) to grasp your brilliant theorem:
> "larger variances ARE EQUAL TO much smaller variances"   Bravo!
>
> > Beginning to understand why this is usually doled out in a
> > series of classes?  (all of which EF has probably taken)
>
> Yep.  That's easily $100,000 worth of education -- but it's broken up
> into managable chunks.  They shove it up your ass a nickel at a time.
>
> ...I'm sure you'll enjoy it,
>
> Mark B.
> --
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