FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   PreferencesPreferences   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Forum index » Science and Technology » Physics
absolute zero
Post new topic   Reply to topic Page 3 of 228 [3408 Posts] View previous topic :: View next topic
Goto page:  Previous  1, 2, 3, 4, 5, ..., 226, 227, 228 Next
Author Message
Ken S. Tucker
science forum Guru


Joined: 30 Apr 2005
Posts: 1230

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: Help: I need to understand the Lorentz force Reply with quote

Androcles wrote:
Quote:
"Ken S. Tucker" <dynamics@vianet.on.ca> wrote in message
news:1107306782.467519.204700@l41g2000cwc.googlegroups.com...
Yup...fuses/circuit breakers are vital if brats are around...



Yeah, but we weren't being brats. We used to ring doorbells
and run away to be brats. Playing with electricity was.. well...
honest, nothing to be ashamed of.
Unless you shocked your sister deliberately, of course.
Parents should know the difference. Then I had two girls
myself and they never did anything like it, so I couldn't
put that into practice. Still, my grandson knows how to take out
the potting shed window with a good kick to a football, he's
scored 3 times now. How much fun is that?



The old boy had piles of Nichrome (stove wire) stashed,
so I did an experiment, on my bedroom floor (oak) and
kept shortening the NiCr wire connection to the 120V.
Normally in a stove it's red, possibly with an orange
tinge. Well, you connect the wires out of the socket
and make the connection shorter and shorter on the
NiCr length, is really super...goes from orange to
yellow to white.
But get this, I observed it goes slightly green just
before it melts down. I presume that was a Quantum
experience.


Oxidation, perhaps?

That might be it, duplicate the experiment,
maybe in nitrogen, that's cheap.

Quote:
The nearest I came to that was a deliberately
broken light bulb with the filament left intact to light a
firecracker.
Androcles

A good friend of mine is a world famous rocketeer,
"Richard Nakka", he has an excellent web-site.
I designed "ultra-low current" igniters to assist
rocketry ignition, based on filaments, he has my
designs posted.
BTW, I was a brat when I started building those,
but to my credit, it made setting off pipe-bombs
a lot safer, compared to a fuse, likely prevented
kids from getting injured as easily.
Ken
Back to top
Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

PD wrote:
Quote:
Don1 wrote:
Yes; a rotating merry-go-round will indeed cause riders to be
thrown
outward.

I see. And you have no doubt heard of this being called "centrifugal
force".
Tell me, what is the agent that causes centrifugal force? I can
account
for gravity (the earth) acting on a rider, friction from the
merry-go-round's surface acting on a rider, the normal force due to
the
merry-go-round's surface acting on a rider.... What is the agent that
is pushing or pulling outward?

PD

The agent is the friction of the surface, which you say you understand;
which carries the riders around the center: Which, since they aren't
firmly attached to this surface; which itself _is_ firmly attached,
tends to fling them away along a tangent.
Back to top
OG
science forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 135

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

"OG" <owen@gwynnefamily.org.uk> wrote in message
news:41fed6bc$0$19159$cc9e4d1f@news-text.dial.pipex.com...
Quote:

What is the point you are trying to make?
Are you asking for advice from us as to the difference; or are you
trying to offer insight to us about the difference?

Hey Don,

you haven't answered this question yet!
Back to top
Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: This business about scales Reply with quote

PD wrote:
snip<
Quote:

I was hoping you'd say SI.
The SI unit for force is a newton (N), not kgf.
Cite a URL that lists otherwise, Don.

PD

Before the newton came into being and common usage - in the early
1900's - the metric system used grams and kilograms as weight: Grams
for things like medicine, and kilograms for groceries and such.

It set a precedent where to this day people still use them as uits of
weight. For one reason, they are so convenient, and they had got into
the habit of using them in their specifications: Which led to the
distinction of grams and kilograms _force_, and grams and kilograms
_mass_.

It's no surprise to me that the pound was considered as a unit of mass:
The pound-mass.

Don
Back to top
Don1
science forum Guru


Joined: 28 Apr 2005
Posts: 1859

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: This business about scales Reply with quote

Double-A wrote:
snip<
Quote:

I think we should go back to the hogshead as our basic unit of
measure.
Filled with 63 gallons of corn liquor would give us our basic unit of
mass!

Double-A

As if 50 gallons isn't already too heavy to handle; try adding another
13 gallons @ 8 pounds each and break out the hand trucks (;^)
Back to top
TomGee
science forum Guru


Joined: 25 Mar 2005
Posts: 636

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: Questions regarding particles and waves Reply with quote

Prism wrote:
Quote:
I understand that a photon can be described as a particle and as a
wave.
Which it is at any given time depends on the observer. My difficulty
is
that though a particle travels in a straight line from point A to
point B
doesn't a wave radiate outwards to all points.


Yes, if it is an electromagnetic radiation wave, and it is better to
say that it radiates in a spherical fashion.


Quote:

I.e. if an event releases a single photon, can the event only be
observed
from a single direction or from all directions?


If you mean does a single photon have a wave, yes, but one wave only,

and yes, it is a sperical wave. That is the reason why it appears as
two photons in the two-slit experiment.
Quote:


As a wave is a photon also able to travel in a straight line with no
divergence?


Ha! Ha! I asked a similar question here before and no one had a

reasonable answer. They came up with the nonsense of "probabilities"
just as they did here. The only way there is a rational answer to the
question is the way my model of the U. explains it. In my model, light
is created by the collision of a lightwave with an invisible particle
which is Dark Matter. The collision transforms the particle into a
visible one and thus a photon is created. The photon stays there but
as the wave moves on through the media of Dark Matter, it lights up
objects for us to see them.

Good question about the photon and about gravitation, too. I don't
have the answer yet about gravitation, but I'm working on it. You are
right in being confused because theories are so ridiculous at times
that confusion is the correct response to them. When you don't get a
specfic and satisfactory answer to your questions, you can be sure it
is because those you asked don't know the right answer. Most of the
time they just parrot current theory and even then there is no
guarantee they understand the theory.

TomGee
Back to top
ošin
science forum Guru


Joined: 05 May 2005
Posts: 408

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

Quote:
I see. And you have no doubt heard of this being called "centrifugal
force".
Tell me, what is the agent that causes centrifugal force? I can
account
for gravity (the earth) acting on a rider, friction from the
merry-go-round's surface acting on a rider, the normal force due to
the
merry-go-round's surface acting on a rider.... What is the agent that
is pushing or pulling outward?

PD

The agent is the friction of the surface, which you say you understand;
which carries the riders around the center: Which, since they aren't
firmly attached to this surface; which itself _is_ firmly attached,
tends to fling them away along a tangent.

Nope. Centrifugal force is associated with the acceleration of the mass
(f=ma in a vector sense) towards the center due to dv/dt.
Back to top
ošin
science forum Guru


Joined: 05 May 2005
Posts: 408

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

"PD" <pdraper@yahoo.com> wrote in message
news:1107352386.007681.37110@c13g2000cwb.googlegroups.com...
Quote:
o<eth>in wrote:
Hmm. Let's see. Density has units mass/length^3. Bulk has units
length^3. In order to get a quantity with units mass only, do I
divide
or multiply? Be careful here, Don. If you can't get this right, I'm
not
going to bother explaining anything else to you.

If he gets this wrong, I really will have to make that long avoided
decision
to put poor old Don into my killfile. I would hate to do that, but if
he
gets this one wrong, I really have no choice left. I hope he makes
the right
choice here!

FWIW, in another thread, Don has acknowledge that the answer is
"multiply".

Oh! I missed that... thanks for the info... I really did not want to kill
file him, but I do have my standards!!!

Is Don OK? I mean is he happy, and able to take criticism? I do not want to
be too nasty if he is fragile.
Back to top
N:dlzc D:aol T:com (dlzc)
science forum Guru


Joined: 25 Mar 2005
Posts: 2835

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

Dear odin:

"opin" <ošin@ragnarok.com> wrote in message
news:F7GdnfX0n793JpzfRVn-oQ@whidbeytel.com...
Quote:

"PD" <pdraper@yahoo.com> wrote in message
news:1107352386.007681.37110@c13g2000cwb.googlegroups.com...
....
FWIW, in another thread, Don has acknowledge that the answer is
"multiply".

Oh! I missed that... thanks for the info... I really did not want to kill
file him, but I do have my standards!!!

Is Don OK? I mean is he happy, and able to take criticism? I do not want
to be too nasty if he is fragile.

He thrives on attention. If that is "OK", then he is OK. He is as
ignorant, or as bullheaded, as necessary to get what he needs. "Shouting
him down" doesn't seem to make a difference.

David A. Smith
Back to top
PD
science forum Guru


Joined: 03 May 2005
Posts: 4363

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

o<eth>in wrote:
Quote:
I see. And you have no doubt heard of this being called
"centrifugal
force".
Tell me, what is the agent that causes centrifugal force? I can
account
for gravity (the earth) acting on a rider, friction from the
merry-go-round's surface acting on a rider, the normal force due
to
the
merry-go-round's surface acting on a rider.... What is the agent
that
is pushing or pulling outward?

PD

The agent is the friction of the surface, which you say you
understand;
which carries the riders around the center: Which, since they
aren't
firmly attached to this surface; which itself _is_ firmly attached,
tends to fling them away along a tangent.

Nope. Centrifugal force is associated with the acceleration of the
mass
(f=ma in a vector sense) towards the center due to dv/dt.

That would be "centripetal force". There is no such thing as
centrifugal force, strictly speaking, though lots of people use the
term cavalierly, just as they use the term "weightlessness" for Shuttle
astronauts.

PD
Back to top
PD
science forum Guru


Joined: 03 May 2005
Posts: 4363

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: This business about scales Reply with quote

Don1 wrote:
Quote:
PD wrote:
snip

I was hoping you'd say SI.
The SI unit for force is a newton (N), not kgf.
Cite a URL that lists otherwise, Don.

PD

Before the newton came into being and common usage - in the early
1900's - the metric system used grams and kilograms as weight: Grams
for things like medicine, and kilograms for groceries and such.

It set a precedent where to this day people still use them as uits of
weight. For one reason, they are so convenient, and they had got into
the habit of using them in their specifications: Which led to the
distinction of grams and kilograms _force_, and grams and kilograms
_mass_.

It's no surprise to me that the pound was considered as a unit of
mass:
The pound-mass.

Don

Ah, see, I thought you were talking about THIS century. Especially when
you were talking about what metric committees "say" (not "said") and
what the standards "are" (not "were").

The current unit of mass corresponding to a pound of weight is called a
slug. There are 2.2 slugs/kg.

What the common population uses as terminology for weight and mass is
indeed unfortunate, but it has no bearing on the more careful
definitions used in physics. After all, football color commentators all
refer to a runner's "speed", "momentum", "force" and "kinetic energy"
as if they were all equivalent.

PD
Back to top
tadchem
science forum Guru


Joined: 03 May 2005
Posts: 1348

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: Questions regarding particles and waves Reply with quote

TomGee wrote:
Quote:
Prism wrote:

<snip>

Quote:
I.e. if an event releases a single photon, can the event only be
observed
from a single direction or from all directions?


If you mean does a single photon have a wave, yes, but one wave only,
and yes, it is a sperical wave. That is the reason why it appears as
two photons in the two-slit experiment.


As a wave is a photon also able to travel in a straight line with
no
divergence?


Ha! Ha! I asked a similar question here before and no one had a
reasonable answer.

A Soliton
http://mathworld.wolfram.com/Soliton.html
is a stable isolated traveling wave solution to a set of equations that
obeys a superposition-like principle (i.e., solitons passing through
one another emerge unmodified).

The Unified Maxwell Equations - a linear, second order differential
equation in a fourth-dimensional tensor space (indistinguishable from
Einsteinian space-time) -

http://mathworld.wolfram.com/dAlembertian.html
http://mathworld.wolfram.com/WaveEquation.html

permit a soliton solution that is a product of a planar travelling wave
and a travelling Gaussian 'envelope' function (which insures
integrability).

This solution to the equation exhibits different properties depending
one which operators are used to extract which parameters from the
function - the wave-like properties (associated with the travelling
wave function) and the particle-like properties (associated with the
Gaussian envelope) are mutually exclusive, just as the wave and
particle properties of the photon are mutually exclusive.

Tom Davidson
Richmond, VA
Back to top
ošin
science forum Guru


Joined: 05 May 2005
Posts: 408

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: What's the relationship between density and bulk? Reply with quote

Quote:
Nope. Centrifugal force is associated with the acceleration of the
mass
(f=ma in a vector sense) towards the center due to dv/dt.

That would be "centripetal force". There is no such thing as
centrifugal force, strictly speaking, though lots of people use the
term cavalierly, just as they use the term "weightlessness" for Shuttle
astronauts.

Yes, OOOOPS, my bad!
Back to top
Igor Khavkine
science forum Guru


Joined: 01 May 2005
Posts: 607

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: Boltzmann Ergodicity Reply with quote

kontrapunktjazz wrote:
Quote:
i have a question regarding the definition of ergodicity by Boltzmann
in its original meaning, i.e. that a system is to be called (I)
ergodic
if it visits ALL states in phase-space/energy-surface over the
course of time (in contrast, i call a system (II) quasi-ergodic if it
visits
all regions of finite area on the energy surface, i.e.
a weaker form of the earlier statement).

now, postulate (I) has been proven to be false by Rosenthal and
Plancheral in 1913. as a consequence from postulate (I),
it is also known that given enough sampling time averages
of an observable A should equal the ensemble average, i.e.
A> = A_time (III)

now, here is my question. i once read that postulate (I) must also
be incorrect, because in relation (III) the left-hand side is an
integral
over a surface, while the right-hand side is an integral over a curve
on the surface, which must be different if the phase-space dimension
is greater than 1. unfortunately, i don't quite follow the argument
(of
course i understand that equality (III) cannot hold if the 2 sides
are not
equal, but i dont really get how this is expressed using surface
integrals).
apparently, this is a theorem from topology, which i
am unfortunately not too familiar with.

Just because <A> is an integral over phase space and A_time is an
integral the trajectory does not mean that <A> and A_time can never be
equal. It does mean, though, that if they are equal, then only on
special occasions.

Say you want to evaluate A_time as a limit of Riemann sums. Then you
sample a bunch of points from the trajectory and average A over them.
But these points are also points in phase space, hence you can use them
to calculate a Monte Caro approximation to the average <A>. Looking at
the situation from this angle, it is obvious that <A> will equal A_time
in the limit of infinitely many samples only if the sample points
become dense in every region of phase space and are distributed
according the the Boltzmann distribution (or whatever distribution you
are using on the phase space). Ergodic systems are precisely the ones
where this condition holds.

Hope this helps.

Igor
Back to top
TomGee
science forum Guru


Joined: 25 Mar 2005
Posts: 636

PostPosted: Thu Mar 24, 2005 5:41 pm    Post subject: Re: Questions regarding particles and waves Reply with quote

Tom Davidson wrote:

"This solution to the equation exhibits different properties depending
one which operators are used to extract which parameters from the
function - the wave-like properties (associated with the travelling
wave function) and the particle-like properties (associated with the
Gaussian envelope) are mutually exclusive, just as the wave and
particle properties of the photon are mutually exclusive."

I thought you agreed with PD, but he says the two are not mutually
exclusive?

Anyway, the issue is not the duality of light, but the question of how
there can exist such a duality at all. My model offers the only proper

solution in claiming that the photon does not travel along with the
lightwave. As the lightwave expands in a spherical fashion, gaps
the particles would appear and they must be filled in or the theory
falls. There is no notion yet as to how new photons would be added
to the gaps created as the lightwave expands and the associated
particles move apart, except by the use of "probability" arguments
which are nonsensical when applied to this particular paradox.

TomGee
Back to top
Google

Back to top
Display posts from previous:   
Post new topic   Reply to topic Page 3 of 228 [3408 Posts] Goto page:  Previous  1, 2, 3, 4, 5, ..., 226, 227, 228 Next
View previous topic :: View next topic
The time now is Tue Dec 12, 2017 9:54 pm | All times are GMT
Forum index » Science and Technology » Physics
Jump to:  

Similar Topics
Topic Author Forum Replies Last Post
No new posts Regression equation using absolute errors draccarlawpet Math 3 Tue Jun 27, 2006 5:39 pm
No new posts Maxwell's equation suggests absolute space and defy TWO N... guskz@hotmail.com Relativity 14 Thu Jun 08, 2006 1:46 pm
No new posts "Measuring Our Absolute Velocity" Klim Relativity 1 Thu Jun 01, 2006 11:57 am
No new posts "Measuring Our Absolute Velocity" Klim Particle 0 Thu Jun 01, 2006 11:57 am
No new posts "Measuring Our Absolute Velocity" Klim New Theories 0 Thu Jun 01, 2006 11:56 am

Copyright © 2004-2005 DeniX Solutions SRL
Other DeniX Solutions sites: Electronics forum |  Medicine forum |  Unix/Linux blog |  Unix/Linux documentation |  Unix/Linux forums  |  send newsletters
 


Powered by phpBB © 2001, 2005 phpBB Group
[ Time: 0.0376s ][ Queries: 16 (0.0094s) ][ GZIP on - Debug on ]