Date: Tue, 25 Oct 2011 11:15:24

Author: Cliff Bettis

Subject: Re: Two Speeds

Post:

This is a multipart message in MIME format.

------=_NextPart_000_008B_01CC9307.64AAEFC0
Content-Type: text/plain;
charset="us-ascii"
Content-Transfer-Encoding: 7bit

Jerry,



I am not sure if this would work: dominoes set in a row so that they knock
one another down. If you adjust it so that they are fairly far apart but not
too far, the falling speed might be faster than the wave.



Cliff



From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Zani, Gerald
Sent: Tuesday, October 25, 2011 10:26 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Two Speeds



Matt,

Yes, the automobile traffic jam is the analogy that is used in almost every
Astro text.

But how to show that? - Jerry

On Tue, Oct 25, 2011 at 10:25 AM, Matthew Bobrowsky wrote:


Not a demo, but the analogy I often use for galaxy density waves is an
automobile traffic jam. Cars drive into the traffic jam rather quickly,
move through it somewhat slower, and then speed up as they leave the traffic
jam. So, like the density waves, this is a situation where the cars (
representing stars) move faster than the traffic jam (representing a density
wave) moves.

Matt

========================================
Matthew Bobrowsky, Ph.D.
Director, Lecture Demonstration Facility
Department of Physics
University of Maryland
College Park, MD 20742-4111

Tel: 301-405-6045
E-mail: msb@umd.edu
http://www.physics.umd.edu/lecdem/
========================================





On 10/25/11 10:10 AM, "Zani, Gerald" wrote:

Tappers,

I need a demo that shows a pattern moving at a speed that is slower than the
particles within the pattern.

For example, a pulse traveling in a slinky shows the opposite effect. Each
coil of a slinky will individually move slowly while the wave pulse travels
quickly.

That is the opposite of what I am seeking. All the wave machines that I
have, longitude wave machines, transverse wave machines, slinky, spring, and
string all show the elements of the material moving slower than the wave
pattern itself.

I need the opposite.

I am seeking to show a pattern that will move slow and the matter within the
pattern move fast.

One example I can think of which I cannot show in class is a water wave in
the ocean. The water wave itself moves slow, while the water within the
wave circulates about quickly.

Any ideas?

Thanks,
- Jerry

BTW for the curious this is to show an analogy for the Astronomical behavior
of the Spiral Density Wave of a galaxy and the motion of the stars within
the spiral density wave.






--
Gerald Zani
Demonstration Manager
Physics
Brown University
(401) 863-3964


------=_NextPart_000_008B_01CC9307.64AAEFC0
Content-Type: text/html;
charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

Jerry, I am not sure if this would work: dominoes set in a row so that they =
knock one another down. If you adjust it so that they are fairly far =
apart but not too far, the falling speed might be faster than the =
wave. Cliff From:=
=
tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On =
Behalf Of Zani, GeraldSent: Tuesday, October 25, 2011 =
10:26 AMTo: tap-l@lists.ncsu.eduSubject: Re: =
[tap-l] Two Speeds Matt,Yes, the automobile traffic =
jam is the analogy that is used in almost every Astro text.But =
how to show that? - JerryOn =
Tue, Oct 25, 2011 at 10:25 AM, Matthew Bobrowsky =
wrote:Not a =
demo, but the analogy I often use for galaxy density waves is an =
automobile traffic jam. Cars drive into the traffic jam rather =
quickly, move through it somewhat slower, and then speed up as they =
leave the traffic jam. So, like the density waves, this is a =
situation where the cars ( representing stars) move faster than the =
traffic jam (representing a density wave) =
moves.Matt=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3DMatthew Bobrowsky, =
Ph.D.Director, Lecture Demonstration FacilityDepartment of =
PhysicsUniversity of MarylandCollege Park, MD =
20742-4111Tel: 301-405-6045E-mail: msb@umd.eduhttp://www.physics.umd.edu/lecdem/=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3DOn 10/25/11 10:10 AM, "Zani, Gerald" =
wrote:Tappers,I need a demo that shows a pattern moving at a speed that is slower =
than the particles within the pattern.For example, a pulse =
traveling in a slinky shows the opposite effect. Each coil of a =
slinky will individually move slowly while the wave pulse travels =
quickly.That is the opposite of what I am seeking. =
All the wave machines that I have, longitude wave machines, transverse =
wave machines, slinky, spring, and string all show the elements of the =
material moving slower than the wave pattern itself.I need the =
opposite. I am seeking to show a pattern that will move =
slow and the matter within the pattern move fast.One example I =
can think of which I cannot show in class is a water wave in the =
ocean. The water wave itself moves slow, while the water within =
the wave circulates about quickly.Any ideas?Thanks,- =
JerryBTW for the curious this is to show an analogy for the =
Astronomical behavior of the Spiral Density Wave of a galaxy and the =
motion of the stars within the spiral density =
wave.-- Gerald =
ZaniDemonstration ManagerPhysicsBrown University(401) =
863-3964
------=_NextPart_000_008B_01CC9307.64AAEFC0--



Back