Any students here?
Edward Green
others are silent: possibly ill-health or that undiscovered country,
from whose bourn
no traveller returns. What I'm curious about is if there are any
students of physics here: graduate, undergraduate, amateurs or
otherwise? Even the cranks seem to have fled ... no doubt in concert
with the bulk of the professionals, since being insulted by just
anybody is no fun.
Graham Lee
Yep, you've got yourself a nice shiny undergraduate student here (final
year, MPhys degree). I've got to start a dissertation project soon, and
it looks like it's going to be on numerically modelling spin-Peierls
distortions in low-dimensionality lattices, but there are a few other
things to be considered.
Graham.
Phil Holman
"Edward Green" <null...@aol.com> wrote in message
news:2a0cceff.0310...@posting.google.com...
> After a hiatus, I return to sci.physics. I see some regulars, while
> others are silent: possibly ill-health or that undiscovered country,
> from whose bourn no traveller returns.
Yes I've noticed the same thing. I wonder what Franz is doing?
>What I'm curious about is if there are any
> students of physics here: graduate, undergraduate, amateurs or
> otherwise? Even the cranks seem to have fled ... no doubt in concert
> with the bulk of the professionals, since being insulted by just
> anybody is no fun.
Thick skin is an asset.
On the subject of learning Physics, I'm trying to figure out the
absolute contribution of precession to steering a bicycle.
No this isn't another *what stabilizes a bicycle* thread but what is the
actual torque about the steering axis from leaning the bicycle at any
given rate considering a given angular velocity and mass moment of
inertia of the front wheel.
I believe this to be somewhat different from the standard gyroscope
equations Torque = dL/dt or w(precession) = mgr/L etc. mainly because
the wheel is supported at both ends of the axle and movement occurs in
all three axes. There is also the difficulty in separating the mechanism
of steering trail and mass imbalance of the handlebars when attempting
to do a conservation of energy analysis. Anyone?
Phil Holman
Bill Vajk
> I believe this to be somewhat different from the standard gyroscope
> equations Torque = dL/dt or w(precession) = mgr/L etc. mainly because
> the wheel is supported at both ends of the axle and movement occurs in
> all three axes. There is also the difficulty in separating the mechanism
> of steering trail and mass imbalance of the handlebars when attempting
> to do a conservation of energy analysis. Anyone?
Most handlebars are balanced. Oddball resistance is caused by
things like brake cables and shifter (if on the handlebars)
cables ignoring, of course, the rider. You'll also, if you're
getting into this depth, have to look at the fact that the wheel
is often not plumb and the resistance introduced by the tire
is off center.
You sure you want to get into all that?
Sam Wormley
>
> "Edward Green" <null...@aol.com> wrote in message
> news:2a0cceff.0310...@posting.google.com...
> > After a hiatus, I return to sci.physics. I see some regulars, while
> > others are silent: possibly ill-health or that undiscovered country,
> > from whose bourn no traveller returns.
>
> Yes I've noticed the same thing. I wonder what Franz is doing?
Franz indicated he was going to devote his time to learning [more]
GTR. I should do that too... Participation in USENET does have some
merit, so I'll split my time for now.
Phil Holman
"Bill Vajk" <bill9...@hotmail.DITCHTHIS.com> wrote in message
news:lhAkb.830027$uu5.146454@sccrnsc04...
Absolutely and I already have somewhat although I'm attempting to
eliminate these in this particular exercise. BTW the handlebars,
brakelevers and whatever other paraphernalia is attached to them are all
located forward of the steering axis with a result that when leaning the
bicycle (even when stationary) the steering will flop in the same
direction as the lean due to mass imbalance. Also due to the tire
contact point being several cm behind the steering axis (trail), the
weight of the bicycle when leaned has a lateral component that also
tends to turn the wheel. We can eliminate these by suspending a
riderless bicycle off the ground and removing the handle bars etc. If we
spin the wheel at x rpm and lean the bicycle at a rate of y degrees per
second, what is the precession rate of the steering? I guess this frames
the question in simpler terms without the added complications you
mention.
Phil Holman
Bill Vajk
snip
> We can eliminate these by suspending a
> riderless bicycle off the ground and removing the handle bars etc. If we
> spin the wheel at x rpm and lean the bicycle at a rate of y degrees per
> second, what is the precession rate of the steering? I guess this frames
> the question in simpler terms without the added complications you
> mention.
Brings it back into reasonability, IMO.
Subsequently you might add the other factors back in
one at a time and you'll be able to allocate the
effects to come up with not only a final outcome but
a reasonable allocation of each of the other influences
as well. Who knows, it might even lead to some bicycle
redesign.
Now that starts to sound like a fun project.
Dave Typinski
>What I'm curious about is if there are any
>students of physics here: graduate, undergraduate, amateurs or
>otherwise?
How about a non-traditional (older) undergrad mechanical engineering
student?
Astrophysics and cosmology would surely be the most interesting of
vocations; however, I note an unfortunate and distinct lack of help
wanted ads for astrophysicists and cosmologists.
>Even the cranks seem to have fled ... no doubt in concert
>with the bulk of the professionals, since being insulted by just
>anybody is no fun.
I've been trying to figure out why that happens as much as it does in
most usenet groups.
What's interesting is that the vocal crankophobes have a choice to
employ a filter; or, at the very least, to scroll to the next message
in the queue. That would work fine for known cranks. Of course,
they've also the choice to rail on ad nauseam against a crank, as if
this will somehow make said crank go away.
Looking at this from an efficiency standpoint, I can't see why an
honest - if unenlightened - question rates less than an honest
response. If the OP ends up firmly resisting any and all attempts to
remedy a small part of their ignorance, then one might think most in
the group would PLONK 'em and call it a day.
That said, and lest I throw stones in my glass house, I acknowledge
the certain gratification had at verbally and intellectually beating
the tar out of some dolt who deserves it, efficiency be damned.
Perhaps people with a bent for physics are just an irritable lot - in
which case the discussions here proceed as one might expect.
--
Dave Typinski
http://home.alltel.net/trapezium
Timo Nieminen
> On the subject of learning Physics, I'm trying to figure out the
> absolute contribution of precession to steering a bicycle.
Apparently there are some quite sophisticated computer models of
motorbikes; if you could get hold of one, it might be a place to start.
Ran across some papers on the subject some years back, these are probably
findable via the usual abstract databases.
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
student
>After a hiatus, I return to sci.physics.
Welcome back. Sci.physics is just not the same without you.
>I see some regulars, while
>others are silent: possibly ill-health or that undiscovered country,
>from whose bourn
>no traveller returns. What I'm curious about is if there are any
>students of physics here: graduate, undergraduate, amateurs or
>otherwise?
"Otherwise". I have to count myself as atalented amateur or semipro,
since like a lot of degree holders, I went to industry immediately
after graduation...but I can still permit myself the conceit of
considering myself a student, as long as I still engage in study
(serious or not).
>Even the cranks seem to have fled ... no doubt in concert
>with the bulk of the professionals, since being insulted by just
>anybody is no fun.
True...and any time one posts to usenet, he leaves himself open
to insults of one kind or another...eventually you decide you don't
care because it comes with the territory, or (like me) you just start
to post semi-anomalously...
Bill Vajk
> Perhaps people with a bent for physics are just an irritable lot - in
> which case the discussions here proceed as one might expect.
If this place were actually populated by people with a
bent for physics that might be true. There's a broad
spectrum here, and very much of the "sailor on leave"
mentality.
Activity comes, as everywhere in usenet, in waves. Lulls
are to be expected.
Bill Vajk
> True...and any time one posts to usenet, he leaves himself open
> to insults of one kind or another...eventually you decide you don't
> care because it comes with the territory, or (like me) you just start
> to post semi-anomalously...
Do insults affect you less because of the anonymity?
Laurel Amberdine
Wishful amateur student here. But I think you knew that.
--
- Laurel * * * http://amberdine.com
Minor Crank
news:tBzkb.2688$np1....@newsread3.news.pas.earthlink.net...
> Yes I've noticed the same thing. I wonder what Franz is doing?
Franz is doing well. I had an email from him a few months ago. He felt he
was wasting too much time here arguing with the crackpots, and wanted to
spend his remaining years on more productive pursuits. A big personal
project of his is to -really- study and understand GR.
He's pretty active on uk.rec.gardening, by the way.
Minor Crank
student
Generally speaking, they don't sting any less, but what anonymity does
do is make them irrelevant.
Without exception, every shameful "spitting match" I've ever seen
on Usenet occurs because one or more parties feels like his or her
credibility is threatened. That is not part of the picture here.
Again, generally, anybody who posts anonymously is saying "I make no
claim about credibility at all beyond the content of this post".
Which means
1) if I engage in any pretentions beyond "student" I will just look
foolish. That is a hell of a lot harder to avoid that than it looks,
by the way. But it is OK with me, I'm not looking to gain anything
here in that regard.
2) an anonymous post is ethically constrained not to make specific
personal judgements, and it is easy to satisfy this constraint because
such anonymous judgements are meaningless anyway. There is no such
constraint against discussing content however, especially if comment
had been solicited at large.
3) nobody in his right mind makes unprovoked personal attacks on an
anom poster, which keeps things a bit more civilized. Actually Tom
Potter was not far from the truth with his digression on "mimetic themes".
Who cares to insulte a theme?
So, if everything is working as it should, attention is focussed on
content only. Rather appropriate for a physics newsgroup.
>
>
Bill Vajk
> So, if everything is working as it should, attention is focussed on
> content only. Rather appropriate for a physics newsgroup.
Of course you're addressing primarily anonymous postings but
that's the way it "ought to be" for everyone, of course.
The reality is a far cry from that, however. Usenet has very
few participants who value ideas more than personal agenda. I'm
glad if your approach is working well for you. Many others take
anonymity and remoteness as a license to freely abuse others.
FrediFizzx
One would hope that everyone here is a student of physics in one way or
another. I know that I will be a student of physics for the rest of my
life, hopefully. No one has all the answers (or questions) yet.
FrediFizzx
Timo Nieminen
> One would hope that everyone here is a student of physics in one way or
> another. I know that I will be a student of physics for the rest of my
> life, hopefully. No one has all the answers (or questions) yet.
If you do physics research as a job, and you stop learning, you have a
problem. Is a researcher a student? Well, that's a different question,
and really a matter of how broadly one is willing to define "student".
Mark Fergerson
> After a hiatus, I return to sci.physics. I see some regulars, while
> others are silent: possibly ill-health or that undiscovered country,
Uh? I've seen you pop in occasionally in the past couple
weeks. Or was that a cat again?
> from whose bourn
Glad you haven't identified with that yet...
> no traveller returns. What I'm curious about is if there are any
> students of physics here: graduate, undergraduate, amateurs or
> otherwise? Even the cranks seem to have fled ... no doubt in concert
> with the bulk of the professionals, since being insulted by just
> anybody is no fun.
Dedicated anateur here.
Interesting psychological point you raise; all the pros
"go to commercial" at the same time, all the cranks "leap to
the fridge". Can't wait for the next round (match? chukker?
rubber?).
Mark L. Fergerson
Ed Keane III
Does a semester of chemistry in high school count?
What ever happened to Jim Carr?