Subject: Reaction time & car accident
Date: Sun, 24 Oct 1999 21:00:03 +0100
From: "Ray Holloway" <middx at>
To: <hwang at>

I have only just found your wonderful web-site & have tried the accident
experiment, it really is a good lesson for us drivers.Perhaps it should be
included in driving tests.
I had not appreciated the "knock on" effect until I noticed that although
I could stop in time those behind me could not.
I found that at 100 mph I had to allow 75 feet between cars for them all
to stop & even then it was not succesful every time.  A wet road would of
made it much worse.
Thanks for a very interesting site, although I have no formal education in
Physics I find it fascinating, so I am going to try the other experiments
Regards,  Ray Holloway
                                     ray at

Subject: Electromagnetic wave propogation
Date: Thu, 21 Oct 1999 15:45:24 +0100
From: "Arif Zubairi" <zubairi at>
To: "'hwang at'" <hwang at>


I was recently scouring the net looking for a suitable picture to
demonstrate the orthogonal mode of an electromagnetic wave in an optical
fibre for a presentation on polarisation dispersion (my artistic skills are
nil). I came across your moving Java applet description of an EM wave and
was suitably impressed as its exactly the type of picture I'm looking for. I
was wondering whether you might have still pictures of the sort that I might
be able to post in a Powerpoint presentation. If you do I would be much
obliged. Thanks

Arif Zubairi

Product Engineering
Nortel Networks
External: %     0181 945 3720
ESN: %          730 3720
E-mail:  ) zubairi at

thanks kindly. Much appreciated.

Subject:  (no subject)
Date: Tue, 19 Oct 1999 12:55:52 -0600
From: Carlos Meraz <meraz at>
To: hwang at

This is cool dud!!

Subject: applet
Date:  Fri, 15 Oct 1999 14:09:41 -0400
From:  Daniel Lemire <Daniel.Lemire at>
To: hwang at

Good day,

I checked your E/M applet today. Maybe you can help me out...

When I set both E and M fields to zero, I would expect the particule to
move at a constant speed in a constant direction (or possibly stay still).

Yet, no matter what I do, it doesn't seem to work.

I am just trying to show to a friend that a charged particule standing
still in a magnetic field won't feel a thing... if there is not E field.
Your applet would be perfect... but it doesn't give the desired result.

Daniel Lemire

Subject:  Re: applet
Date:  Fri, 15 Oct 1999 22:11:30 -0400
From: Daniel Lemire <Daniel.Lemire at>
To: Fu-Kwun Hwang <hwang at>

Thanks for your quick reply!

Date: Wed, 13 Oct 1999 00:35:28 -0700 (PDT)
From: Alex Ladikov <shelton1983 at>
To: hwang at

Dear Fu-Kwun Hwang

Your sight is very very interesing and very very
helpful for us. If you like physics problems we can
send you what we have. We think that our relationship
can be very helpful for you and for us.

Sincerely yours, physics club of lyceum "Leader" Kiev
Ukraine(post Soviet republic)

Date: Sat, 09 Oct 1999 12:15:20 -0400
From: A Friend <a.friend at>
To: hwang at

nice page.

thank you.

Date: Mon, 4 Oct 1999 14:28:02 -0700
From: "Steve Tyminski" <styminski at>
To: <hwang at>

Cool Stuff!

Subject: Physics java applets
Date: Tue, 28 Sep 1999 22:42:16 +0100
From: "Charles Scott" <C.Scott at>
To: hwang at

I have just recently discovered your web site in an article in "The Herald"
newspaper which is published in Glasgow, Scotland.  I have visited your site
and was very impressed with the work that you have done. I intend to get my
Physics students, who study at Kilwinning Academy, Scotland, to access your
site as part of their coursework.
thank you
Charles Scott

Subject: kepler motion applet
Date: Thu, 23 Sep 1999 06:00:13 -0700 (PDT)
From: lee taishen <leetaishen at>
To: hwang at

Dear Mr. Hwang,

Referring to the kepler motion applet in the below
I find it very interesting. However, I have some
difficulties when using the applet.

1. For second kepler law, the area of the shaded area
and non-shaded area should be the same. However, there
is no data showing what the area is.

2. for third kepler law, i observed that there is no
indication of the period of the planet. There is this
T value indicated in the applet but it is not the
period. i would appreciate if you can explain what the
T value is.

thank you.

best regards

Subject: More Java suggestions
Date: Tue, 14 Sep 1999 14:38:08 +0100
From: Jeff Forssell <JF at>
To: "'hwang at'" <hwang at>
CC:  Claes Ahlin <AI at>

Back in school after a tough summer. My 81 year old mother was visiting
from USA and fell down a stairs and needed help for the 2 months she was
here. Bad luck! Didn't get much done this summer. But the weather was
nice at least.

Hope you扉e had a good summer.

I was checking to see if you multimeter aplet could be used to see in
what situations it would be incorrect (parallell with a LARGE
resistance) but it didn't take that into consideration- it gave the same
reading at 2000 kohm as 10ohm.
See the accompanying picture.

While I惴 at it heres the interpreter for Q basic
in case you want to try the files I sent before.

I've been looking at Walter Fendts Javas. some are  quite illustrative.
One that wasn't was about the "radioactive decay series". Do you have
anything planned there?

I'd like to find an alternating current aplet that would show the charge
acculation resp magnetic field buildup graphically.

I sometime try to show my pupils a water -electricity anology where
pump=voltage spource
small or clogged pipe=resistance
double chamber with elastic membrane=capacitor
turbine with inertial load=inductance
That might be something that could make an interesting Java aplet

I put together a very rough sketch of  the C-L anology:
Jeff Forssell
personal homepage:
my village technology homepage:
Swedish National Institute for Distance Education (SSVH)
Box 3024      SE-871 03 H酺n飉and /Sweden
tel +46(0)611-55 79 48   fax +46(0)611-55 79 80
schools homepage

Subject: SV: re send multimeter plus more ideas
Date: Thu, 16 Sep 1999 12:40:29 +0100
From: Jeff Forssell <JF at>
To:  "'hwang at'" <hwang at>

Thank you!
The aplet seems to work very well.
Some minor problem and a couple of wishes:
1) if I change the range while the meter is connected, the measured
voltage is not updated. (Hmm I tried it again and now it works. But if I
reload the page and turn "ON" directly it reads 4,67V on 10 V range. If
I change to 50 V range,4,76V stays in stead of 4,95V  The Equivalent
circuit is updated directly.)
2) I would prefer a much faster component value change while
continuously pressing mouse <0.1s per change. One can always "fine tune"
with single klicks.
3) I would like a possibility of writing in R2 values also.
(4) Fu Hwang 1999 in lower left, in stead of 1998)

Subject: SV: SV: re send multimeter plus more ideas
Date:  Fri, 17 Sep 1999 07:46:05 +0100
From: Jeff Forssell <>
To: "'hwang at'" <hwang at>
CC:  Claes Ahlin <AI at>

Thank you!

I still have the problem with voltage update on changing range even on
the new aplet (i've tried in both NS 4.5 and IE 3.0).

with a newly opened page:
press ON
V= 4,76V   10 range
change to 50 V    V still 4,76         (equivalent circuit Rs update
change to 10 V    v changes to 4,95
change to 50   V changes to 4,76

The write in window for the values works well. I would (on behalf of
Sweden and some other countries) like even comma "," to be interpreted
as a decimal sign.

Other clarity wishes: prefix the box with "R2" when updating R2 and
suffix the box with "kohm" when R values being set.

V  [  ]
R  [  ]kohm
R2[  ]kohm

I think the current circuit would be easier to see if you had a wire
connecting rather than 2 ground symbols.

When the Rm box is not checked, it would be good for the Eqivalent
circuit to be altered perhaps like this:
Hope you don't think I'm complaining! I use your aplets a lot! I wish
someone would go through my stuff to help me develop it!

Subject: Very Nice ..... but....more ideas
Date: Sat, 18 Sep 1999 22:12:40 +0100
From: Jeff Forssell <JF at>
To: "'hwang at'" <hwang at>

Very nice!

But I still get the update problem when changing range (both IE 3.0 &
Nets 4.5). Have you tried as the FIRST step after opening the page? I
know that the problem goes away if I do a bunch of other stuff (change
values I think).

One other problem: I think that the multimeters that I扉e used have had
the red  lead positive when in the resistance mode (which makes it
easier to interpret when measuring on active components like diodes).  I
havesn't checked that in reality since I had the thought though.

Reviewing my own work:
I'm mainly interested in getting my web resources polished up for my
Swedish students which mean that it is in Swedish which makes it
difficult for  non Swedes to say much about it.

Subject: physics java applets
Date: Thu, 9 Sep 1999 09:14:43 +1000
From: "Seth Bell" <seth at>
Organization:  Xref Pty Limited
To:  <hwang at>

I have been visiting your site this morning (found via AltaVista) and
playing with the java applets.
A great resource and very educational.  Thank you!
Seth Bell.

Subject: digit shit
Date: Wed, 1 Sep 1999 21:42:06 +0200
From: "Kjell Crafoord" <m-30057 at>
To: <hwang at>

hi there!
really nice java applet, though it took me some time to figure out
why it said wrong answer all of the time when i was completely sure i
got the right one. i had to type 1.0 mm instead of just 1mm, and that
was quite annoying. if you wanted a tip, i guess that is one. keep up
the good work!

Subject: Vernier applet
Date: Tue, 31 Aug 1999 10:31:42 +0100
From: Cathal Flynn <cathal.flynn at>
To: hwang at

Dear Dr. Hwang,
        I have used some of your physics applets and I find them to be excellent.
Well done! At the moment in the Physics Department we are making changes to
our first year physics labs and would like to include your Vernier applet
in one of the labs in order to help the students learn to read a vernier
scale properly. Is is OK if we include the applet in one experiment?
Thanking you in advance,

Yours Sincerely,

Dr. Cathal Flynn
Department of Experimental Physics
National University of Ireland

Subject: mixing light-beam
Date: Sat, 21 Aug 1999 06:44:04 +0700
From: amrat chawla <amratc at>
To: hwang at

Dear Sir,
Your mixing light beam applet is very very instructive. When I show to
my children they were amazed and understand easily of what they learned
at school but never get it clear. You know how schooling in Thailand,
education here is mostly memorising and answer question ! So we parent
have to help our children understand by external help. Your applest is
very helpful tool.

Thankyou for your contribution to people of the world.
With best rgds.
Amrat Chawla.

Subject: online interactive site
Date: Wed, 18 Aug 1999 11:11:06 -0400
From: RAYC1 at
To: hwang at

WOW!!!!!!  Reflection and Refraction is WONDERFUL!!!!THANK YOU

Leslie Marra

lmarra at

Subject:demo for Antonio Nari隳 university
Date: Wed, 18 Aug 1999 07:03:00 +0000
From: fhort at (felipe ortiz)
To: hwang at
your physicals applets are very good! i am a enginering sistems student here in
colombia, and i need the java applets愀ource code.

you can send at my address today.  Is urgent!

Subject: Very Nice Applet
Date:  Sun, 01 Aug 1999 18:34:25 -0500
From: Greg Hecht <ghecht at>
To: hwang at

Very interesting and educational java applet, sir.  My compliments.

I am not an astronomer but studied Kepler's laws years ago.  Your applet
is the best tool I have ever seen to allow one to grasp the concepts.
Thank you for creating and sharing it.


Greg Hecht, MCSE
The Riverpoint Group, Ltd.
Kansas City

Subject:  Help !
Date:  Fri, 23 Jul 1999 05:15:13 +0800
From: "StyleWan" <style at>
To: <hwang at>

Dear Sir,
    I appreciate the Physics animations from you very much !   I want to learn java so that
I can make my animations.  Would you please give me some guides by introducing
some reference books and related materials ?  Thank you very much indeed !!
P.S.  I am a Physics teacher.  I have certain programming knowledge of Basic and

Date: Wed, 14 Jul 1999 23:23:57 +1000
From: "Antony Tribbick" <tribbick at>
To:  <hwang at>

Nice java applet..
Demonstrates very nicely what I was experimenting on with golf balls

Date: Mon, 12 Jul 1999 09:28:18 -0000
From: "Edie Dukek" <edukek at>
To: <hwang at>

Your entire site is wonderful!  Thanks for taking the time to make this
excellent information acccessable to my students!

Edie Dukek

Subject: physics sites
Date: Thu, 8 Jul 1999 22:10:16 -0700
From: "E. Ou" <ou at>
Organization: California Institute of Technology
To:<hwang at>
I really like your physics pages. Especially the java applets, those are
great. I know your pages are old and I don't know if you update them
anymore, but keep up the good work :)

Subject: web page
Date: Mon, 5 Jul 1999 16:15:46 EDT
From: CLBlom at
To: hwang at

Dear Fu-Kwun,

I appreciate your web pages:  Billards and Physics, and 2D Collision.
I am a high school science teacher, preparing to teach an "Integrated
Chemistry and Physics" class, and I anticipate using your web pages in the
classroom.  Thanks!

Carrie Doyle

Subject:  web site
Date: Wed, 23 Jun 1999 21:44:18 -0400
From: "Monty McGee" <mlmcgee at>
To: <hwang at>

Thank you very much for this web site; extremely interesting.  I work with
physics, chemistry and computer programming, and find this very helpful.

Monty McGee

Subject: SV: SV: SV: Doppler applet wish (&propagation)
Date:  Mon, 7 Jun 1999 07:06:02 +0100
From:  Jeff Forssell <JF at>
To:    "'hwang at'" <hwang at>
CC:     Claes Ahlin <AI at>

I am in a bit of a hurry with other things also, but I have looked at the
applets and they look good!

You made a very nice interface for seeing the reflection of different
polarized waves. Both numerical and visual without cluttering up the
previous features!
Jeff Forssell
personal homepage:
my village technology homepage:
Swedish National Institute for Distance Education (SSVH)
Box 3024      SE-871 03 H酺n飉and /Sweden
tel +46(0)611-55 79 48   fax +46(0)611-55 79 80
schools homepage
residence +46(0)611-22144

>Fr幩:  Fu-Kwun Hwang[SMTP:hwang at]
>Skickat:        den 7 juni 1999 03:20
>Till:  Jeff Forssell
>Ang嶒nde:      Re: SV: SV: Doppler applet wish (& propagation)
><<Fil: Doppler.html>><<Fil: Doppler.class>><<Fil: propagation.html>><<Fil:
>Jeff Forssell wrote:
>> I notice that if I enter a user ratio in propagation, the top and bottom
>> field maintain the colors it had before, no matter whether the ratio is
>> more or less that 1. Maybe it would be good to have the optically more
>> dense media become gray.
>>   I see that you have put in the angles also. I thought of suggesting
>> that but I forgot to write it.
>> A new idea I got was is: could the intensity of the beam colors show how
>> much of the radiation is reflected and transmitted.  No big need, but it
>> would be nice, even if just approximate. But that would be complicated
>> because polarization comes in also. That would be a challenge! Maybe
>> better with a separate applet. But you have made some amazingly compact
>> versatile applets before. (Like the lens /mirror one!)
>Try the attached java applet and let me know if this is what you want.
>Pick p-wave or s-wave from the top left selection.
>> I think there maybe is a serious flaw in the doppler applet: example
>> with the default settings the wavelength is supposed to be 20. If I
>> measure on the right it is 20 and left it is 60   if i change the speed
>> to 4 the measured distance between wavecrests becomes: 42 38  which
>> seems to indicte that the wavelength is actually 40.  I' m in a bit of a
>> hurry until wednesday so I may have made a mistake.
>In my previous java applet, the distance between wave front is not necessary
>related to the wavelength. Those are wave front generate at fix time interval
> not necessary equal to period of the wave).
>In this attached java applet it is modified so that the wave front is
>with the same period of the wave. Try it and let me know what you think.
>I will try to add sound effect at the next release.
>But you will have to wait a few days,
>I will have to do other stuff first.

When I wrote a moment ago about a BASIC program I had and decimal
acceptance, I got to thinking maybe your applet could be expanded (or a
new one with similar components so It could replace this program for
practicing reading analog scale instruments:

It is written i Qbasic. (There is also less common scale where range 12
V is to be interpretted from a printed scale with 6 V as full scale-
I've seen similar things in reality but that aren't very common so I
might take that away.)
That I don't have more scale divisions depends on 2 things:
1) I want students to practice estimating tenths of scale divisions
2) lack of time (laziness?)

I m sending  this qbasic file  (and another on Vernier scale)
As a friend of "old" computers I have versions for CGA and Hercules
screens too

Jeff Forssell

Yes we really do use commas for decimals!  We even use (sometimes)
periods as thousand separators.

We do end our sentences with . though.

I was amazed to hear from you so quickly. I found myself wondering what
is the time In Taiwan? We are at 17 degrees longitude and taiwan at 120
so that should mean that when you sent your letter it must have been
around 6 pm your time. (I don't know if you use Daylight saving time

Both the class files were smaller than the old ones! How is that
possible? Did you do some code cleaning when you added features?

Were you able to open the Qbasic files?

Subject: Congratulations!!
Date:  Sat, 05 Jun 1999 10:18:27 -0300
From:  "Tarso F. Cassol" <tarso at>
To:    hwang at

Dear Mr. Hwang

I visited your WEB page with hte aplicattions on JAVA to demonstrate
some Physics
laws and I found it very interesting.
I would like to send you my congratulations for your work.
Perhaps my Physics students may use and learn more science with your
Sincerely, Tarso.
Physics Departament of Universidade Federal de Santa Catarina.

Subject:  Very exciting!
Date: Thu, 3 Jun 1999 21:53:43 +0400 (EET DST)
From: Derya Oktay <derya at>
To:  hwang at

Hello I`ve visited your homepage, and I must say that I found very
wonderful and despite I did not see you or talk with you, I liked you,
thanks for your hardworking. I appreciate you, if you accept.
Good luck.

             Ege University
             Department of Computer Engineering
             Derya Oktay
             deryaoktay at
             icq# 23349443

Subject:   (no subject)
Date:  Sat, 29 May 1999 20:41:04 EDT
From:   Lizwoolard at
To:  hwang at

Thank you so much for the creative and very effective physics applets.  I am
a high school physics teacher and I use them frequently on my physics pages.
L Woolard
 <A HREF="">Enloe Physics Web

Subject:   Physics Java Applets
Date:   Sat, 29 May 1999 15:42:27 -0700 (PDT)
From:   rhys hughes <drh38 at>
 To:  hwang at

Are your Physics Java applets for sale. I find them very interesting,
but due the cost of Internet phone calls (ie; in the U.K.) I'd rather
install them on my PC.

Thank you


Subject:  Doppler applet wish (& propagation)
Date:     Wed, 26 May 1999 08:25:32 +0100
From:     Jeff Forssell <JF at>
To:       "'hwang at'" <hwang at>

I like the doppler applet (as I do most of your Javas) but when I was
about to try to use the x,y coordinate display to measure the difference
in apparent wavelength on different sides of the source, I found that
the display changed to angle. Which is very good in some cases but it
ought to be easy to have both. Either i 2 windows or perhaps left click=
angle, right click=coordinates

Another wish would be that the "propagation applet (which I love!) could
have the top medium become darker than the bottom when it愀 n value is
greater and increase the choice of n1/n2 to include day glass about air
below. (I know and appreciate the possiblity to set the n/n ratio to
0.667, but if you feel like adding something I悲 appreciate the above)

thank you
Jeff Forssell
personal homepage:
my village technology homepage:
Swedish National Institute for Distance Education (SSVH)
Box 3024      SE-871 03 H酺n飉and /Sweden
tel +46(0)611-55 79 48   fax +46(0)611-55 79 80
schools homepage
residence +46(0)611-22144

Subject:   SV: Doppler applet wish (& propagation)
Date:  Fri, 28 May 1999 09:28:04 +0100
From:  Jeff Forssell <JF at>
To: "'hwang at'" <hwang at>
CC:    Claes Ahlin <AI at>

Thank you! That was fast!

The doppler applet is more flexibla now. I would though prefer if one
could lefdt press and drag between 2 freely chosable points and get
delta x, delta y; rather than only distance from source.
 Another detail is that the y coordinate is negative upwards which is
not the most common matematically, though those distances aren't so

You might be interested to know that the doppler applet was referred to
in one of the questions in the latest National Exam in Physics. But we
aren't allowed to disclose the contents. (So erase this letter :-)  )

I assume the index.html page was in Chinese (It sure wasn't English!)

The propagation applet is perfect.  Whoops I just noticed that for large
angles of incidence, the incident beam became solid red!

Subject:  SV: SV: Doppler applet wish (&propagation)
Date:     Mon, 31 May 1999 05:43:14 +0100
From:  Jeff Forssell <JF at>
To: "'Fu-Kwun Hwang'" <hwang at>

I notice that if I enter a user ratio in propagation, the top and bottom
field maintain the colors it had before, no matter whether the ratio is
more or less that 1. Maybe it would be good to have the optically more
dense media become gray.

  I see that you have put in the angles also. I thought of suggesting
that but I forgot to write it.

A new idea I got was is: could the intensity of the beam colors show how
much of the radiation is reflected and transmitted.  No big need, but it
would be nice, even if just approximate. But that would be complicated
because polarization comes in also. That would be a challenge! Maybe
better with a separate applet. But you have made some amazingly compact
versatile applets before. (Like the lens /mirror one!)

I think there maybe is a serious flaw in the doppler applet: example
with the default settings the wavelength is supposed to be 20. If I
measure on the right it is 20 and left it is 60   if i change the speed
to 4 the measured distance between wavecrests becomes: 42 38  which
seems to indicte that the wavelength is actually 40.  I' m in a bit of a
hurry until wednesday so I may have made a mistake.

Subject:  more ideas for doppler and propagation applets
Date:  Wed, 2 Jun 1999 09:29:17 +0100
From:    Jeff Forssell <JF at>
To:    "'Hwang'" <hwang at>
CC:   Claes Ahlin <AI at>

I just got an idea f顤 the doppler applet that I hope you will like:
[ ] listener       in top part

if someone checks in the box, the user can place a "listner" anywhere in
the window.
Whenever a wavefront passes him the computer makes a sound (a beep or
tick or something).
For example: I place my listner in front of the advancing source:
beep beep beep beep beep (then it passes) beep    beep    beep    beep
If I place my listener off to the side I would get a less pronounced
(what should happen when a supersonic "bang" arrives should of course be
some loud noise).

Another wish for the propagation applet:
increase the n1/n2 options with "diamond to air". I think people
tend to be fascinated by diamonds and they do have a spectacularly
high n value. (I saw that in another persons refraction applet, which
also included the possibility to show wavelength changes (also different
colors for the different wavelengths) but I prefer yours otherwise)

Thank you for your answer. I have a lots of tests to grade now at the
end of the term. Perhaps it is the same for you.

Subject:  Re: (no subject)
Date:     Mon, 03 May 1999 18:44:25 +0200
From:     Peter Brichzin <peter.brichzin at>
To:       Fu-Kwun Hwang <hwang at>

Hallo  Mister Fu-Kwun Hwang,

thank you very much for sending all the files. To get a
good multimedia lesson is very important for me,
because it would be evaluated. A good evaluation will
give me a job es teacher.

I tried to understand your program. It's not easy
because my knowledge in Java is very basic. My problem
is now:
If I want to change the power of r in aceleration or
force   F~ a ~ 1/r^2 to
F~ a ~ 1/r^x
then I have it to change in the method drivs of class
movingProjectile. (it works)
But this method never is called in whole
projectileOrbit.class. And to give a different exponent
to acceleration I have to give a argument to method
derivs (or are there other possibilities.

Is it possible that  derivs is callt in rk4.
Could you send me please or could you help me
in an other way with an idea to cahnge it.
Sorry that I ask you so much. Probably your time is
rare, but it would be a big help for me.
Thank you very much

Peter Brichzin

P.S: To get an imagination whatb I want I send you a
modified version: I added a Checkbox to change force.
But I can't get the connection between checkbos and
method derivs.

Subject:  Physics applets comments
Date:     Wed, 28 Apr 1999 12:56 -0500 (CDT)
From:     Michael Blackstock <michael.blackstock at>
To:       hwang at

Fu-Kwun Hwang,

    Hello, I am an amateur American physics enthusiasts.  Your physics
page has caught my attention and I would like to let you know they
are wonderful.
    Under Dynamics on 6. Circulation motion and Centripetal force, I
would like to know if it possible to change the velocity of the circular
motion and change both the weights on either end of the string without
changing it's radius?

Thank you,

Michael Blackstock

Subject:  Re: Physics applets comments
Date:     Fri, 30 Apr 1999 10:46 -0500 (CDT)
From:     Michael Blackstock <michael.blackstock at>
To:       hwang at

Fu-Kwun Hwang,

    Thank you very much for the adjustments you made to the following
request I sent you!


Michael Blackstock

Date:     Tue, 27 Apr 1999 23:05:21 +0100
From:     "Anthony Vinters" <Tony at>
To:       <hwang at>

I have found the tansverse and longitudinal waves. They are excellent,
exactly what is needed. Being able to show the the phases of particles
relative to each other is very useful.
I will be able to direct my students to your site so they can see for
Once again thank you for your efforts the results are most pleasing.
Rishworth School

Subject:  Re: Applets
Date:     Mon, 26 Apr 1999 23:44:29 +0100
From:     "Anthony Vinters" <Tony at>
To:       "Fu-Kwun Hwang" <hwang at>

Dear Fu Kwun Hwang,
I have received your applet. This is fine, the diagrams look exactly
right. I cannot run the applet as my email seemed not to contain any
software to animate the diagrams, only the pictures themselves. Can
you put this on your site so I can try it out?
Perhaps you would consider writing an applet to show a how a
 Transverse wave is made up of oscillating particles: this would be a
most valuable teaching tool.Also a Longitudinal wave to show how the
wave particles vibrate in the same plane as the plane of propagation?
Both applets would work well alongside your excellent SHM applet.
Once again thank you for answering my request, certainly material
such as this makes Physics much more enjoyable to teach and learn.
With very best wishes,
Anthony Vinters. Head of Science Rishworth School.

Subject:  Applets
Date:     Thu, 22 Apr 1999 18:20:15 +0100
From:     "Anthony Vinters" <Tony at>
To:       <hwang at>

Dear Fu Kwun Hwang
Thank you for the Applets, they are excellent! I have used them for teaching
my students about Simple Hamonic Motion and the Principle of Superposition.
Have you done one which shows the motions of particles within a Transverse
Wave and a Longitudinal wave? It would be interesting to look at the
particle motion and compare them within these two wave systems. If it were
possible to show the phase relationship between any of the particles even
better! Showing that any particles that are 2Pi radians out of phase with
each other are 1 wavelength apart is something that students can find
difficult to understand without the help of a moving model.
Once again thank you for all your work.
With best wishes:
Rishworth School

Subject:  Virtuel Physics
Date:     Tue, 20 Apr 1999 11:33:53 +0100
From:     S鷨en R鷮el <SR at>
To:       hwang at

Dear colleque

Your site is vere good, but it is very difficult to load. It takes more than 30

Yours sincely

assistant professor  Soeren Roejel
The Technical University of Denmark

email:  sr at

Subject:  Color, light, and shadow.
Date:    Mon, 12 Apr 1999 10:14:01 -0500
From:    "John Clement" <clement at>
To:      <hwang at>

An applet that would be invaluable in teaching how light and color work
would be one that had a flashlight with different color filters red, green,
blue, cyan, magenta, yellow, clear.  Then the user could view various
objects in those same colors using the flashlight.  This would be an
illustration of how "classical" color reflection works.

Subject:  bravo from Italy!
Date:     Fri, 02 Apr 1999 18:38:10 +0200
From:     g.pavesi at (Pavesi Giovanni)
To:       hwang at

I am a physics teacher from Parma, Italy, and I had much appreciate your
applet, that I 'll use during my school lesson. Excuse my poor english,
but however congratulations and thanks for your good work!
                     Paola Pannuti

Subject:  Re: model for an idel gas
Date:     Tue, 23 Mar 1999 13:40:57 +0100
From:     Stefan Berger < at>
To:       Fu-Kwun Hwang <hwang at>

dear mr. hwang

thank you for helping! now it works!

sincerely, stefan berger

Subject: Re: about your page in
Date:    Tue, 23 Mar 1999 16:19:43 -800
From:    jflores1 at
To:      Fu-Kwun Hwang <hwang at>


thanks 4 the help
my teacher liked the animation...!!!

and the rest of the class too..!!

once again thanks

Subject:  model for an idel gas
Date:     Mon, 22 Mar 1999 22:44:29 +0100
From:     Stefan Berger < at>
To:       hwang at

dear mr. hwang,

i'm a teacher for physics in germany. this is the third time i launched
your site in the internet. but when i try out your applet i get problems
by changing the number of particles. always i'm trying to change this
value it doesn't change the number of particles in the applet. can you
help me?

sincerely, stefan berger, bochum, germany

Date:     Mon, 15 Mar 1999 14:51:24 -0600
From:     "Stan Treanor" <treanor at>
To:       <hwang at>

Great Demo, I'll use it with my students.
Stan Treanor

Subject:  Amazing Teaching Materials !!
Date:     Sun, 14 Mar 1999 05:52:21 +0800
From:     "StyleWan" <style at>
To:       <hwang at>

Dear Sir,
    I am a Physics teacher in a secondary school in Hong Kong.  I found that the java
applets in your web page are excellent teaching materials !!  It would be great to save
the applets for teaching.  However, I could not save the java applets (together with the
homepage) so that I can play them offline.  Would U please help me ?
    Thank U very much indeed !!

Subject:  thank you
Date:     Fri, 12 Mar 1999 14:52:00 -0500
From:     Dany Marquis <dmarquis at RDS.CA>
Organization: R廥eau Des Sports
To:       hwang at
Your application in java to learn how to read a vernier help me.

Dany Marquis

Subject:  Permission to link to your site
Date:     Thu, 11 Mar 1999 10:39:57 -0800
From:     cmcLean <cmclean at>
To:       "'hwang at'" <hwang at>

I would like to commend you on a wonderful site.  The Vernier site is informative and
fun. I wanted to get your permission to link to your Vernier from a Cumberland County
Educational Physics course website.  It was suggested to us that we get permission to
link to any sites so that we don't infringe on any copyright laws.  I appreciate your hard
work.. You can respond to cmclean at
Thank -You for your time.
Carol McLean

Subject:  Physics or Fisica
Date:     Wed, 10 Mar 1999 01:03:52 -0700
From:     Pedro R <zonico at>
To:       hwang at

Mr  Hwang:

First of all, i would like to congratulate you about your PHYSICS HOMEPAGE.

I'm an 18 year old student from Mexico. I study Mechanical and Electrical
Engineering at the ITESM here in my country.

Now your are probably asking: so, what?

Well, i'm taking a physics class in which we have to make several different
kinds of thing on of them, make a HOMEPAGE and include some
links to virtual labs ans stuff like that.

I managed to link some of your applets to my page, that the whole meaning of
this e-mail, to ask for your permission to keep those links, or if you
disagree, just send me an e-mail, and i would gladly erase them.

You can check my homepage (that it hasn't been finished yet) at
and tell me your thoughts.

I would apreciate you could let me keep the links.

Saludos desde Mexico.

Subject:  E&M Waves
Date:     Tue, 09 Mar 1999 00:34:41 -0800
From:     Chun-Te Peter Wu <peterw at>
To:       hwang at

Hi Professor,
        I visited the your E&M website and I am very impressed with the animation
of the E&M waves.  I especially liked the rotations of axis.  Good Job

Subject: Typo found...
Date:    Mon, 1 Mar 1999 11:59:51 -0800
From:    "Chris Holden" <chris.holden at>
To:      hwang at

I happened upon your web site and noticed that the word "Beginning" is
misspelled (you have it as "Begining").  The URL of the page is:

I hope this helps.


Subject:  Your website
Date:     Fri, 19 Feb 1999 19:47:52 -0000
From:     "Bob Arkley" <Bob.Arkley at>
To:       <hwang at>

Thank you! I know almost nothing about physics, but I have had a
great time playing with the applets on your website. I was actually
looking for some simple information for a 13 year old about how
gravity keeps the planets in our Solar System in their orbits, but I
soon forgot about that in the sheer fun of playing. Thanks again
Bob Arkley

Subject:  Thin Lens Java applet
Date:     Fri, 19 Feb 1999 18:00:24 +1100
From:     pevans at
To:       hwang at


I was looking at your applet for the thin lens and really liked it. I am new to applets and
often it is possible to download them so that you can use them off line but I couldn't
work out what to do to download your applet.

I am a secondary teacher and would really like to show it to my students. Would I be
able to get a copy of it please.


Pam Evans
pev at
pevans at

Subject:  (no subject)
Date:     Wed, 17 Feb 1999 18:32:04 EST
From:     JLau325162 at
To:       hwang at

I liked your sight.  And found it very informative.  Hands on experience works
better than just reading the info.  Thank you.

Subject:  Wow!!!
Date:     Wed, 17 Feb 1999 09:25:53 -0500
From:     defaultuser at
To:       hwang at

Your site is fantastic!

I teach high school physics and have been looking for good simulations
to use with my students! This one is a winner!

Very talented work! Keep it up and thanks!!!

Lars Wendt, Hunterdon Central Regional High School, Flemington, NJ .

Date:      Tue, 16 Feb 1999 16:27:13 -0000
From:      Brad Busch <blbusch at>
To:        "'hwang at'" <hwang at>

Your caliper java applet is cool -

Brad Busch
VP Engineering, Class1 Inc.

Subject: physics webpage
Date:    Tue, 09 Feb 1999 15:06:23 -0500
From:    Tony Montana <kreeture at>
To:      hwang at

hey, you're really good. i like your webpages alot. our physics teacher
referred us to your pages, and i think they're pretty cool, especially
with the animations and interactive applets. and plus my mom's heard of
your university (i'm chinese), so rock on!

Subject:  your web-site
Date:     Mon, 08 Feb 1999 22:15:14 -0500
From:     Susan <calla at>
To:       hwang at

I don't have any suggestions, but I think your site is really great and
I like your graphics.

Susan Irlbeck -- physics student in Raleigh, North Carolina, USA

Subject:  your webpage
Date:     Mon, 8 Feb 1999 20:55:47 EST
From:     Bananas337 at
To:       hwang at

your webpage is awesome! my physics teacher, Ms. Woolard,
(lizwoolard at assigned us your webpage as our homework tonite. you
have done a great job! thanks!

stephanie yeh
bananas337 at

Subject:  your webpage
Date:     8 Feb 99 16:40:40 PST
From:     shefali oza <shefalib at>
To:       hwang at

WOW!  my physics teacher (Mrs. Woolard) suggested your website as an extremely
useful tool to help us learn about oscillations and SHM, as well as other
physics concepts. your site really is truly wonderful and it is obvious that
you have put plenty of time into making it.  it has been very helpful in
clarifying some places where i was having difficulties.  i am so glad my
physics teacher gave me your website address and i would
like to congratulate you on such a wonderful job.
shefali oza (north carolina)

Subject:  Physics Virtual Labs
Date:     Mon, 8 Feb 1999 18:34:46 -0500
From:     "Tonran" <tonran at>
To:       <hwang at>

Hello, I am a physics student living in the US. My teacher gave our class
your web page address to help us learn about waves and oscillations. I thank
you for you taking the time to write the java for these demonstrations. They
helped me learn the material.

Thank you,
Brian Senter

Subject:  Too slow to be followed
Date:     Fri, 5 Feb 1999 18:25:49 +0530
From:     "Er. Ravinder Avasthi" <R1A2 at>
To:       <hwang at>

        Your applets are verry-2 good but your server is very slow
,forcing not to even approach your site.
                           thank you

Subject:  Java Physics Demonstrations
Date:     Fri, 5 Feb 1999 23:05:19 -0500
From:     "Thomas Del Rosso" <t.delrosso at>
To:       <hwang at>

From the Fermat page: "I am not a professional programmer, I am a physicist."

....but you're pretty good at both.   :)

Great stuff.  Thank you for your work.

Subject: Physics Java applets
Date:    Thu, 4 Feb 1999 22:25:53 +0800
From:    "Tay Kian Hwee" <ayi at>
To:      <hwang at>

Dear Mr Hwang,

    Hi there. I'm teaching physics in a secondary school in Singapore. I've
found your applets very useful in my teaching but wonder if it is possible
for them to be downloaded into my computer so that I do not need to access
the internet everytime I wish to use them in my lessons. Would appreciate it
very much if you could make the applets available. Thanks.

Mr Tay Kian Hwee

Date: Tue, 2 Feb 1999 22:39:22 -0200
From:     "Marcilio Carneiro" <marcilio_roberto at>
To:       <hwang at>

Hi Mr Hwang:
  I?m from Brazil I worked as Physics about 10 years ago and since
that time I had a  desire : to make softwares for Physics teaching.
The DOS interfaces I used to have forced me to give up. Last year
(after spendig some time learning Windows based programming) I
 restarted the project but once again I didn?t like the results. I
used Delphi 3.0 (Pascal Object Language) and made about 100 programs
( mechanics and eletricity) but when I saw your programs I felt even
more disappointed with the ones i had done . Yours are brilliant ,
fantastic . Don?t you sell them ? I?m interested in many of them.
One : sugestion: Don?t use weak green colors I hardly can see them .
For instance the one you used  in Vactor addition,
Thank you and congratulations for your excellent work (I wish I was
talented as you are)
Marcilio Carneiro

Subject: help for all
Date:    Fri, 29 Jan 1999 12:53:11 +0100
From:    Jose Villasuso <villasu at>
To:      hwang at

Dear Sir:FU-Kwun Hwang.

I am a High School teacher from La Corunha , Spain ( Galicia ) near

I realy like yours appelets of  Java  and I am used to work with them in
my classes.
If you don`t mind I would like to know if is posible for you to do one
about this:
A force pulling a block on a slope, and showing the forces growing when
you aplay diferents pulls.
Also it would be a plesure if you could do another  one: a block moving
in horizontal , changing the force angles when you pull the block, and
at the same time showing the celerity of the block. The most eficient
angle to move is when the  tg (angle) = coefficient of rubbing

Sorry for my english

I?m very pleased for having found your work, amazed work, which is very
useful for my students and also for me.
Before all, thank you very much for your work and help.

Pepe Villasuso

Subject: Kudos on your excellent site
Date:    Thu, 21 Jan 1999 11:28:26 -0500
From:    "Robert Craig" <rcraig at>
To:      hwang at

Your Java Applets are of great use in showing elementary students some
of the basics of science. You are to be commended for your hard work and
Sincere thanks
Robert M. Craig
Talenetd and Gifted Coordinator
West Alexandria, Ohio USA

Subject: Re: Regarding your Cyclotron Applet.
Date:    Wed, 6 Jan 1999 14:32:25 +0000 (WET)
From:    Joao Manuel Henriques <jmh at>
To:      Fu-Kwun Hwang <hwang at>

Hi Again.
 First let me apologise for not responding sooner, but I was on vacation.
 Second, I would like to thank you for having sent the Source Code, it
really helped alot...
 Now it is my turn to help you out (if U want to), I made another program
that simulated: ' Attwood's Machine', since you dont have it on the list I
could send you a copy of it ..(it is in C though...)
 Let my know if you want it or not...BTW it also uses RK4, but it looks
diferent from your routine....

 Anyway thank you very much.

On Fri, 18 Dec 1998, Fu-Kwun Hwang wrote:

> Joao Manuel Henriques wrote:
> > Hi.
> >  I am a student of the University of Lisbon and I was a assigned a task to
> > simulate the cyclotron.
> >  It has been really hard to make something that actually resembled a
> > cyclotron, but i still cant make the electron spin according to the
> > frequency of the Voltage.
> >  Can you please help me out?
> >
> >  Here is what I need to know:
> >  -I calculated a formula that calculates Theta, but the center of the
> > circular movement is constant. In other words the Ray of the circunference
> > increases, but the center doesnt change like it should.
> >  Can you tell me the formula to theta?
> >
> This is not the way I did it. There is a better way to do it:
> If you know the velocity V and force (F=qVXB) at time t,
> you will be able to calculate velocity at t+dt;
> If you know the position and velocity of a particle at time t,
> you will be able to calculate next position at time t+dt.
> Repeat the above loop, you will know the next position and velocity at next
> moment t+dt;
> >
> > There is something else I want to ask.
> > Is there a possibility of you sending me the source code?
> >  I know this is an unusual request, but it would really make me understand
> > how the program really works. My source code is so complex that not even I
> > can understand it, and above all it doesnt simulate the cyclotron right.
> >  I would be very gratefull if you could send it. I promise I wouldn't
> > change the code and say that the program is mine. All I need to know is
> > how you did it.
> >
> >  Well, please e-mail me back with a response, preferably one with the
> > reply i want to get.
> >
> >  Thank you for your attention.
> >
> >
> >                      Joao Henriques
> >   
> The source code is attached with this e-mail. But you will need to know about
> the
> Runge-Kutta method to understand the rk4 class.

Subject: Physics of Light
Date:    Tue, 5 Jan 1999 21:13:57 -0400
From:    "Reg & Lori Coppicus" <reg.lori.coppicus at>
To:      <hwang at>

        Enjoyed very much the physics of light showing internal reflection, and
diffusion of the laser.
I look forward to examining more related Java applications, but a very good

Reg Coppicus
Nova Scotia, Canada

Subject: Thanks
Date:    Wed, 9 Dec 1998 16:07:30 -0500
From:    louise heaven <gw_heaven at>
To:      Fu-Kwan Hwang <hwang at>

Thank you very much Mr Hwang, for your reply to my plea about the pendulum.
 I was very pleasently surprized to find you had done so.  Thankyou again.
I would also like to say that you have a very good web page and i shall
look there first when i am researching physics.

Joseph Heaven

Subject: Re: thanks!
Date:    Sat, 05 Dec 1998 18:52:08 -0500
From:    dgoodwin <dgoodwin at>
To:      Fu-Kwun Hwang <hwang at>

Thanks so much for taking the time to send me the http for circular motion and
ang. mo.  I really appreciate it.  It's great stuff.  Bye for now.  Dave G.

Fu-Kwun Hwang wrote:

> I am really sorry for the late reply. This message was misplaced.
> There are two java applets related to the angular
> Kepler motion:
> and circular motion
> dgoodwin wrote:
> > Do you have any applets on angular momentum??
> >
> > Fu-Kwun Hwang wrote:
> >
> > > dgoodwin wrote:
> > >
> > > > We were reviewing vector addition this evening at a study session.
> > > > Someone asked about help from the internet, so we searched and happened
> > > > to find your page.  There were a few "ah-ha's" when the program showed
> > > > the parallelogram method for adding vectors so clearly.  Thanks.
> > >
> > > I am very happy to know that you are enjoy the java applets. Any
> > > suggestions you might have about my java applets will be highly
> > > appreciated! Or , if you would like to have java applet one any topic
> > > related to physics,
> > > Just send me a note! Enjoy the virtual physics laboratory!

Subject: Note of Appreciation
Date:    Tue, 17 Nov 1998 13:12:15 AST4
Organization: Dartmouth High School
To:      hwang at

Dear Fu-Kwan Hwang,
     I am a physics teacher at Dartmouth High School in Dartmouth
Nova Scotia Canada.  I discovered your applets a couple of weeks ago
and am still exploring them.  They are an invaluable resource for me,
my students and for use in teaching in my classroom.  I have used one
so far and built my lesson around it...a lesson I had taught before
but it added that extra pzazz and interest for my students.  We were
using the reaction time applet.  I showed them how to do the
calculations using the motion equations and then we gathered data for
stopping distances using the applet.  They were also thrilled to see
the internet used in such a meaningful way...they have become
skeptical of the junk out there.
     Please accept my sincere thanks for the excellent quality of the
applets and I hope your work is able to continue.

Geary Mac Millan
Science Dept Head
Dartmouth High School

Date:    Tue, 10 Nov 1998 23:00:38 -0500
From:    "Mark C. Barnett" <mcbarnet at>
To:      <hwang at>

fantastic web page.  i'm doing a report on wave division multiplexing and
found your web site very useful and easy to use.  thanks for the help.


Subject:  Links2Go Key Resource Award
Date:     Mon, 9 Nov 1998 14:50:44 -0500
From:     awards at

Congratulations! Your page:
has been selected to receive a Links2Go Key Resource award in the
Java Applets topic!

The Links2Go Key Resource award is both exclusive and objective. Fewer
than one page in one thousand will ever be selected for
inclusion. Further, unlike most awards that rely on the subjective
opinion of "experts," many of whom have only looked at tens or
hundreds of thousands of pages in bestowing their awards, the Links2Go
Key Resource award is completely objective and is based on an analysis
of millions of web pages. During the course of our analysis, we
identify which links are most representative of each of the thousands
of topics in Links2Go, based on how actual page authors, like
yourself, index and organize links on their pages. In fact, the Key
Resource award is so exclusive, even we don't qualify for it (yet ;)!

Please visit:
to find out more about this award, and to download graphics if you wish
to display this award on your page.

Once again, congratulations on your award!
Links2Go Awards
awards at

P.S. If you are not the author or maintainer of this page, please accept
our appologies. We would appreciate it if you would forward this email
to the appropriate person.

Subject: java applets
Date:    Sat, 31 Oct 1998 21:30:46 -0500
From:    Cliff Sampson <clifford at>
To:      hwang at

Fu-Kwun Hwang,

Many thanks for the java applets that you so kindly sent me. The
teachers in Singapore were very impressed with them and I am sure that
your mirror site at the Singapore Chinese girl school must be over
worked. The implimentation of these java
applets together with others that I have obtained from programmers
around the world and my successful integration of computer based
technology into the science curriculum has resulted in my nomination by
the college for the Prime Minister's Award for Teaching Excellence
(Canada). This
is indeed an honour for me and I am required to present some of my work
which obviously includes some of your java applets. My work is purely
pedagogical in nature and focusses primarily on use of technology as an
effective teaching tool. It also involves how various systems and
strategies can be adapted to fit various learning styles.

I would therfore like your formal permission to use these applets and to

submit copies of them ( with full formal acknowledgement of your
authorship) in support of my nomination.

Many thanks for your help and support.


Cliff Sampson

Clifford Sampson PhD
Appleby  College
540 Lakeshore Road
Ontario, L6K 3P1

Subject: thanks!
Date:    Wed, 21 Oct 1998 21:21:49 -0400
From:    dgoodwin <dgoodwin at>
To:      hwang at

We were reviewing vector addition this evening at a study session.
Someone asked about help from the internet, so we searched and happened
to find your page.  There were a few "ah-ha's" when the program showed
the parallelogram method for adding vectors so clearly.  Thanks.

Subject: Hello!!!!
Date:    Sun, 11 Oct 1998 15:30:39 -0400
From:    "yoadrienne" <yoadrienne at>
To:      <hwang at>

     I just wanted to write in order to thank you for the lovely sites you have
online regarding virtual physics.  I teach 12th grade/advanced physics in the
USA and have assigned your virtual labs to my students to do as extra
credit at home.
We have all been truly delighted by the work you have done.
Thank you again and best wishes!
                                         Adrienne Lauver
                                         Apex High School
                                         North Carolina
P.S.  The kids also wanted me to mention that they really like the way you
"talk"!      :-)

Date:    Fri, 09 Oct 1998 09:43:01 PDT
From:    "Michael Breen" <breenmj at>
To:      hwang at

Wow, I've been teaching 17 years and finally I can show students doppler
effect and sonic boom. Thanks

Subject:  Physics of Pool
Date:     Wed, 07 Oct 1998 14:13:44 -0400
From:     Adam Lapatin <alapatin at>
To:       hwang at

Hi, I just played around with your java applet for billiards and I was
wondering if you know of any good books and/or websites about the
physics of pool.  Any information you have about the subject would also
be extremely helpful ... if you haven't guesses I'm writing a report on
the physics of pool.



Subject:  Appreciation
Date:     Thu, 1 Oct 1998 22:50:42 +0800
From:     "HUI Man-yan Mark" <markhmy at>
To:       <hwang at>

I am a high school physics teacher in Hong Kong.  I happened to visit your site and found that your simulation
of physics phenomena and concepts are extremely useful.  I intend to use them for my lessons.  I anticipate that
my students will enjoy them very much.  Thanks for your great work for a school teacher like me.

Mark HUI


Subject:  (pas d'objet)
Date:     Wed, 23 Sep 1998 11:46:22 +0200
From:     croussel <chrystel.roussel at>
Organization: ENSCR
To:  hwang at

Very interesting program for my studients
chrystel roussel

Subject: java applet on shadow/image
Date:    15 Sep 1998 11:16:06 EDT
From:    POWERS at
To:      hwang at

Dear Hwang,

Our fifth grade science teachers love your applet on color mixing and
images. Please feel free to create activities that are appropriate on
the elementary level.....they are highly needed and greatly appreciated
(especially on magnetism and electricity). Thanks again.

Wendy Power
wpower1 at

Subject: Your Page
Date:    Mon, 14 Sep 1998 07:30:04 -0700
From:    "Maurice O'Brian (Manpower)" <v-maurob at>
To:      "'hwang at'" <hwang at>

I must say I was impressed with your entry on the web, I found it very
helpful in inderstanding relativity.

Yours etc.
Maurice O' Brien

Subject: Brownian motion
Date:    Sat, 5 Sep 1998 10:18:45 +0100
From:    "Peter Mussard" <p.mussard at>
To:      <hwang at>

The animation is good, but the text 'Green dots are velocity distribution of the
molecules' doesn't make sense.

Peter Mussard

p.mussard at

Subject: You physics java applets
Date:    Fri, 4 Sep 1998 23:28:37 +0100
From:    "Peter Mussard" <p.mussard at>
To:      <hwang at>

Very impressive!

Peter Mussard

p.mussard at

Subject: double-slit applet
Date: Tue, 25 Aug 1998 14:45:37 -0400 (EDT)
From: "James Bo Begole" <begolej at>
Reply-To: "James `Bo' Begole" <begolej at>
To:  hwang at

I liked to older version of the double slit applet better.  The interface
on the old one was much easier to use, although it was slower to run.  I
can't map the frequency to a color in my head.  Can you put up a link to
your old version?

Why am I interested in your applet?  My interest stems from our work on
collaborative learning systems. I have a system called Flexible JAMM (Java
Applets Made Multiuser) that allows the shared use of single-user applets,
such as yours.  Do you mind if we use the old version to test how
difficult it will be for a developer to make an applet that can be used in
this system?

 Flexible JAMM:


Subject: learning from you
Date: Mon, 24 Aug 1998 20:47:51 +0800
From: Edmund J A Ang <edmunda at>
To:   hwang at

I would like to learn from you. How did you write the animated
programmes e.g. vernier calipers. Very interesting.
teacher Edmund ang

Subject: Thanks for great BioSavart
Date: Mon, 24 Aug 1998 22:16:57 -0700
From: "Sunpainter" <sunpaint at>
To: <hwang at>
I was looking for something on the shape of circuit for very small circuit
trying to predict some electromagnetic field changes in the circuit.
I will be using very, very small current.
Your simulation was incredibly, wonderfully helpful!
If I had to do all the math for each current change, it would have taken me forever.
Now I have my figures. THANK YOU THANK YOU!
It is for a strange little generator I am building.
Thank you!

K. Hodge Southern California

Subject: Conservation of Linear Momentum
Date: Tue, 28 Jul 1998 09:14:28 +0800
From: Lim Ai Phing <zuc at>
Reply-To: lap at
To: hwang at
I'm a physics teacher presently teaching my students dynamics.
Your collision java applet is really good, I'll ask my students to take a look here!!
But can I suggest that the colour of the numbers be changed
because yellow doesn't show up much against a gray background?


ubject: Your applets
Date: Fri, 24 Jul 1998 13:13:16 -0400
From: diegel at (Mike Diegel)
To: hwang at
My friend and I had been discussing what a sonic boom is
and I was trying to describe how the sound waves come together to make it happen.
We came across your web page at
and used the applet. We thought it was a fantastic illustration of what a sonic boom is,
and we just wanted to let you know that your work was appreciated.
Thanks for the help.
Mike Diegel

diegel at 966-9100

Subject: Interesting
Date: Sat, 04 Jul 1998 11:57:20 -0700
From: Daniel Murphy <gecko at>
To: hwang at
I'm a student at Olympic College in Bremerton, Washington currently enrolled in a physics class.
We are studying vectors, freefall, velocity/acceleration and projectile motion.
Your web page is great!
I think the answer to the question of case one about the green circle is the arc of zero vertical velocity.
When the object reaches zero velocity, acceleration remains a constant 9.8 m/s(sq) downward.



Subject: Enjoyed your supersonic applet
Date: Mon, 29 Jun 1998 15:30:54 EDT
From: Jrice45515 at
To: hwang at
I enjoyed studying your applet.
I have taken the liberty of making some minor wording changes so that your description will be more grammatically correct.
I wish I were multilingual as you are! ;-)
The location of supersonic airplane.
If an airplane is flying faster than the speed of sound, it will produce a sonic boom or shock wave.
As shown in the right figure, consider an airplane which is flying from A toward B.
A listener is located at C. The sound generated at A travels toward C along the path AC.
The listener hears the sound as the airplane flys toward point B.
( AB > AC ) DC is the path of the sound generated at D to the listener.
The airplane speed is V and the sound speed is Vs.
If AC/Vs > AD/V + DC/Vs [Isn't it unlikely that the shorter path will take a longer time?],
then the sound generated at point D will arrive earlier than sound generated at point A! Funny!
You hear something which happened later and then hear something which happened earlier !
What will you hear if a supersonic airplane flying over you?
Do you know where is the airplane when you hear it?
Can you point out the direction of the airplane just from hearing the sound?
This java applet let you play with such situation.
Press Start to start the animation. A listener is represented by an ear!
You can press the left mouse button and drag it within the screen to change location of the listener.
The program draws sound wave paths to the listener.
The animation will be suspended when the sonic boom arrives at the listener.
Click the right mouse button to continue. The color of the paths changes to blue.
The order in which the sound paths arrive at the listener are shown also.
You can change the ratio of airplane speed of airplane to sound speed and see the difference.

John Rice

Subject: Great jobs!
Date: Sun, 14 Jun 1998 17:37:43 +0800
From: "Robinson Wang" <robinson at>
To: <hwang at>
Dear Mr. Hwang,
Hello! I am a student of the National Tsing Hua University(NTHU).
Maybe you've heard that the Material Science Engineering which is my major.
I'd like to appreciate the great jobs you've done.
At first, I come to this website because of my final-term physical report.
However, when I view the first exam, I can't help finishing all items in this site.
Well, that's all what I want to say about this special work.
Have you a happy time in teaching.

Your sincerely, Robinson Wang '98.6.14

Subject: Web Site
Date: Mon, 8 Jun 1998 18:11:12 EDT
From: LCHARN at
To: hwang at
Hi! I'm a physics teacher in Blantyre High School in Scotland
and I've just discovered your Physics demos site.
When I return to school tomorrow I'll be directing my class to your site first thing.
Well done and thank you...
I'll be a regular visitor from now on.

Subject: problems with cyclotron java applet
Date: Thu, 4 Jun 1998 19:37:38 +0200
From: "Pietro Diviacco" <diviacco at>
To: <hwang at>
My name is Pietro Diviacco. I am an Italian surgeon and live and work in Genova, Italy.
I tried to play Your applet "Cyclotron" but there was some problems.
Some of the images (*.gif 7 and 14) were not available and the applet was not working.
In any case Your applets are very good and interesting (the working ones, of course).
Thank You in advance for fixing the problems.

E-mail address: diviacco at

Subject: Wow!!!
Date: Sun, 03 May 1998 12:47:55 -0600
From: The Lahrs
To: hwang at
I love your thin lens page:
What a great use of Java!
I use Netscape, by the way, and the applet worked just fine and was very speedy.
I've been trying to figure out why a glass rod creates an inverted (about one axis) virtual image.
Do you have an applet for a thick lens, or just a ray diagram that would show this effect?
Is the code still available? The link was not working when I tried.
It would be interesting to develop something like this for seismic waves.
I'm a seismologist now, but my first love is physics,
which was my undergraduate major at Rensselaer Polytechnic Institute.
Thanks again for providing the world this great applet.
John C. Lahr
-- * John C. and Jan H. Lahr * *
JohnJan * *
914 10th Street * *
Golden, Colorado 80401 * *
(303) 215-9913 * * * * *
Subject: Wow!!!
Date: Sun, 03 May 1998 15:39:11 -0600
From: The Lahrs
To: hwang at
I just figured out that the inverted image is not virtual but real,
so everything makes sense now.
Keep up the good work.
John C. Lahr

Subject: (no subject)
Date: Wed, 29 Apr 1998 22:13:08 -0500
From: Dion Sanchez <dion at>
To: hwang at
I want to thank you for this page, it has helped me visualize what a text book could not.
I have been looking for something like this for a long time.
great stuff thanks. dion



Subject: Java 動畫
Date: Mon, 27 Apr 1998 18:44:50 -0700 (PDT)
From: Dan Murray <dbmurray at>
To: hwang at
黃教授﹐你好﹗ 新近﹐我尋找了網際網絡﹐找了有意思有關物理的事﹐
也發現了國立 台灣師範大學的物理系的網頁﹐所以發現了你的許多 Java 動畫。
直到 現在﹐我沒有意識了物理教師創造了那麼許多 Java 動畫。
但是﹐你供 應更多消息是適當。我的電腦是 Windows 3.1 的 PC 。
即使我使用比 較新近的 Netscape (就是 3.05)還不可以看見 Java 動畫。
最低的 電腦需要是 Windows 95。或許你可以給人講解﹐所以阻止挫敗。
我們 有 Windows 3.1 的人應該知道﹐ 惟有看見 Java 動畫的方法大概是買 新電腦。
可惜﹐因為我是物理教授﹐無奈繼續使用我的舊電腦﹗ Dan Murray 謹上



Subject: Refraction Applet
Date: Thu, 23 Apr 1998 10:14:02 -0400
From: Sandee Coats-Haan <LA_COATSHAA at PO.SWOCA.OHIO.GOV>
To: hwang <hwang at>
Is there any way to change the velocity vector and/or the medium thickness
on your refraction applet if you don't have a two button mouse?
Sandee (Lakota East High School Physics)
P.S. -- you have an incredible site

Subject: Lens/mirror
Date: Fri, 03 Apr 1998 16:16:37 -0600
From: Kelly <kpuls at>
To: hwang at
Mr. Hwang, I want to say that your virtual lab was unbelievably helpful to me.
I attend the university of wisconsin-madison and I was having problems with optics concepts.
I went under the internet and searched under lens and mirrors and fell upon your lab.
I am very grateful. I was a little upset last night when I wanted to access the lens mirror applet,
because I couldn't find it.
I guess even the virtual labs have hours of availability.
I guess that's my only suggestion,
which isn't a very necessary one to attend to when most of us can access it during the day.

Thanks again, Chris cechapma at

Subject: Can I add a counter to the mirror site?
Date: Tue, 24 Mar 1998 19:02:33 +0800
From: "tanghb" <tanghb at>
To: <hwang at>
Dear Mr. Hwang,
When I meet the physics teachers of the other schools in Singapore,
they give good comments about the mirror site of Virtual Physics Laboratory.
I think your Java Applets are popular in Singapore.
I am therefore interested to know how many people come to visit Virtual Physics Laboratory
and use your Java applets everyday.
Mr. Hwang, can I add a counter on the contents page?
If so, please let me know.
Thank you.
Tang Hung Bun

Singapore Chinese Girls' School

Subject: I saw a Polarized Rainbow!
Date: Sat, 14 Mar 1998 01:18:24 -0800
From: Neal Rasmussen <nealras1 at>
To: hwang at
I am, as far as I know, the first to see a "Polarized Rainbow"!
I think we should name this phenomona the "Rasmussen-Wang Rainbow". :-)
I am a tornado chaser for 20 years. About 4 years ago I was driving through a McDonald's drive thru.
As it was just after a pretty good storm, I had mys polarized yellow tinted flip-up sunglasses on.
Low and behold I almost dropped my cigarette into my lap.
There off in the east was a double rainbow!
Not the kind I've seen dozens of times where the second one is reveresed and much outside the primary,
but this was immediatly INSIDE the primary!
Gaping with my mouth open and people behind me honking,
I flipped my flip-ups up and the second inner one went away!
I must have sat there for 2 minutes flipping my sunglasses.
The colors were NOT reversed and it looked like one continuous double wide rainbow,
with two complete sets of colors.
I ruled out that the flip-ups where giving double vision as I looked at lights the next day,
streetlights headlights, etc. and no doubles!
Can this possibly be? Could a source of polarized light be at a different angle,
perhaps the sun shining through a cirrus cloud or noctelucent (sp).

Neal Rasmussen nealras1 at

Subject: Thank you for the applet!
Date: Tue, 10 Mar 1998 10:34:26 +0100
From: Uwe Gaertitz <u.gaertitz at>
To: "'hwang at'" <hwang at>
your applet works fine, thanks a lot.
We want to use it offline, for non-commercial demonstration.
I've mentioned you and made references to your site at this local page, however.
Some suggestions/questions:
1. One goal is to maximize/minimize :-)
the flow. But it's so easy, with setting velocity and acceleration to max(min), isn't it?
2. It would be fine to see the flow rate in an extra text field,
cause this is the much interesting output (for me).
3. Perhaps, a "history" of the last flow rates (then you can better see,
whether you have success in maximizing flow rate or not).
Could be a simple text table (over a time intervall), or a graph.

Ciao, Uwe

Subject: Your Doppler effect applet
Date: Sun, 8 Mar 1998 22:39:05 -0600
From: "Michael Vershinin" <vershini at>
To: <hwang at>
Your applet is pretty neat, but since you asked for suggestions...
1) I would not allow the user to set a negative wavelength.
2) If negative source speed is chosen, your source runs off the edge of the window.
3) Negative wave speed is a bit awkward, since your source is actually a sink.
Michael Vershinin

Date: Mon, 02 Mar 1998 13:32:38 +1100
From: masukor <sari.masukor at>
To: hwang at
Hi, been to your physics lab. great stuff.
I teach physics at a junior college here in australia.

I certainly will make more visit to your site. bye.

Subject: java applets
Date: Sun, 01 Mar 1998 01:45:54 -0500
From: Clifford Sampson <clifford at>
To: hwang at
Dear Mr Hwang
I have found your java applets especially those on waves and optics to be particularly facinating and informative.
So much so that I have begun to use them extensively for my grade 11 physics students
at Appleby College in Oakville, Ontario, Canada. ...



Subject: Publishing Your Applets
Date: Tue, 17 Feb 1998 18:38:33 -0600
From: Taha Mzoughi <ccp at>
To: "'hwang at'"
<hwang at>

Subject: Physics Java Applets
Date: Sun, 15 Feb 1998 15:37:15 +0800
From: Stephen Chin <stepchin at>
To: hwang at
Dear Sir, I'm also a Physics teacher, O level, and I am interested and fascinated
by the Java Applets you have created..... they are really good.....
I find them very useful for teaching and demonstrating certain concepts in physics....
I am wondering how do you write a Java Applet....
I have the Java Programmer Kit downloaded from Sun.... but don;t know how to use it.....
please advise
Thanks in advance.
Stephen Chin
-- If we wait long enough we may reap the best harvest....



Subject: Java and Physics
Date: Sun, 15 Feb 1998 09:15:22 +0100
From: lindblad at
To: hwang at
I am a professor of physics at the Royal Institute of Technologu in StockholmSweden.
We do teach Java for programming in Science and I came across your web pages.
Although we do teach Java for Ph.D. students I think there is something that could be learnt
from your beautiful pages. Maybe we will also extend the course to MS levels.
The problem is that we are in physics and Java should be taught by the CS dept, but will they do it our way?
We may try to suggest a course and then some of your web pages could be very useful to the students.
I would therefore like to ask you about your plans etc.
I would hate to have made refs to your pages and then they would disappear one day, smile.
Also, you may have some new ones in mind?
I think something with the uncertainty principle would be very useful. Have you ever considered this?
I am very open for any form of collaboration on this future teaching project.
You can find examples of the present course on the web.
We plan some lecture notes and I hope I can make ref/use some of your examples?
Looking forward hearing from you
// Thomas Lindblad

Subject: Applets
Date: Thu, 12 Feb 1998 16:57:50 -0600
From: Taha Mzoughi <mzoughi at Ra.MsState.Edu>
Organization: Mississippi State University
To: hwang at
Dear Professor Fu-Kwun Hwang:
This is the first of two emails I will be sending you.
I have been familiar with your work for about a year now. To say the list, it is impressive.
I am an assistant professor of physics at MS State University and I try to use the Web for instruction.
I am not a Java programmer. I wrote some stuff with JavaScript.
The URL for my class is:
I am still working on the content and would like to eventually include some of your Java applets.
Obviously maintaining links to your Web site and proper credit.
I have noticed that you have your applets mirrored throughout the word (which is nice)
and I am wondering if it acceptable for you to add another mirror in our server.
I am also interested in having a copy of the applets to run of laptop that is not connected to the Web.
Actually, I am giving a talk about resources on the Web for teaching physics to high school teachers
on the 20 th of February, and I hope to be able to include some of your applets.
I will write a page with links to the applet in your site that I will use in the presentation then place it on our server.
I appreciate your help. You are doing some neat stuff there.
Taha Mzoughi
Assistant Professor
Department of Physics and Astronomy
PO Box 5167
Mississippi State University
Mississippi State, Mississippi 39762-5167
Phone: (601)325 2923
Fax: (601)325 8898
mzoughi at

Subject: animations
Date: Wed, 11 Feb 1998 11:43:06 -0400
From: Hugo Beltrami <hugo at>
To: hwang at CC: hugo at
Hello, I was looking at your site and I was wondering whether it would be possible
to mirror it here at this university. Would you please let me know if this is possible.
Then I would contact our system manager Thank you for your attention
-- Hugo Beltrami
Assistant Professor
Voice: 902-867-2326
Department of Geology
Fax : 902-867-2457
St. Francis Xavier
University e-mail:hugo at
P.O. Box 5000, Antigonish
Nova Scotia, Canada,B2G 2W5



Subject: Your Java Frictionnal Force applet.
Date: Mon, 9 Feb 1998 11:45:31 +0100
From: "leflocht" <leflocht at>
To: <hwang at>
Thanks a lot for your on-line physics lesson.
As a french teacher i would like to ask you the permission to use your applet on a new html sheet
using french as basic language. Of course i would only translate your words( the best i can)
and leave each reference (native URL, mailto.. and comments in original state.)
The reason is that i just gave my students, (aged 17) a exam using the study of this system.
So i would like them to use your applet to get more of this study case by using new parameters
such as Mu and various masses.
This page, if possible, will be added to the site i create for my sudents (it's the very beginning),
you could surf at: and find it using french "Fichiers de TP" in the 1S section.
---- You ask for suggestions ? Of course i've got some.
*first: The masses you use : Are F1 = 10 grams or F1 = 10*g where 10 is kg and g is 9.81 mS-2 ?
(and so on for others )? case 10 grams: we use to calculate Force intensity in Newton (France) case 10 kg:
the mass seems very heavy !
*second: Some lines of your HTML page are not readable for french users because of the asian keyboard
translation,( i think.) Just above the definition table of forces, there is a line i'dont know what it is ?
(caracters like at #& and others not in use in our alphabet but for bad words ...)
The definition for f12 is quite the same it appears like: f12j[number zero]m1 g[symbol for english pound] g
I think we must read: f12 not so different of m1. Mu.g. ad so on for each reading of friction force. -----
I can make, if you look for it, other text translations, so your work to make your work used by french people.
Thanks .
Thierry Le Floch Thanks to disregard my english mistakes.
Thierry Le Floch
Email: leflocht at site
UIN 4557973



Subject: Lenses
Date: Sun, 01 Feb 1998 17:08:13 -0600
From: John Eagle <jwe392 at>
To: hwang at
I think this page is great.
I stumbled into it one night while trying to find some insight on a physics assignment that I had.
I've used it ever since to check my work.
Something that might be helpful to a great number of people
would be a java applet with thick lenses and or two lense systems. Just a thought.
Thank you for taking the time to publish such a page John Eagle



*** Please check out Thick Lenses java applet

Subject: Re:Suggestions
Date: Sat, 31 Jan 1998 11:41:23 -0500
From: "Pierce C. Barnard" <pbarnard at>
Organization: myself
To: hwang at
Hi, I was examining your satellite & projectile motion applet and I found it to be very useful.
A suggestion, you may want to allow a user to set all paramters and
provide a button on the applet to start the applet.
This way the user will not have to keep on readjusting the applet while the projectile is in motion.
Pierce Barnard

Subject: Orbit applet
Date: Fri, 30 Jan 1998 08:44:52 +0530
From: "Surendranath Reddy.B." <bsreddy at>
To: "Hwang" <hwang at>
Dear Mr.Hwang,
I just saw your orbit applet. It was just the thing that I thought I would suggest to you.
Please consider the following suggestions.
Would it possible to show the initial position of the projectile,
its velocity and the angle the velocity makes with the line joining it and the center of the earth
and then give the option to launch.
The distance from the center of the earth could be made large ( twice, thrice.. the radius of the earth)
It would be better if the user gives these inputs by mouse clicks or by entering the values.
( It may be also a good idea to relate these values with (gr)^0.5,
the value required for a circular orbit. One could bring out the concept of escape velocity also.
Warm Regards

Surendranath Reddy.B.

Subject: Request for the secret!
Date: Tue, 27 Jan 1998 23:57:11 +0800
From: "Stephen, W. T. Kwan" <swtkwan1 at>
To: hwang at
Dear Sir,
I am Stephen W. T. Kwan, a secondary teacher in Hong Kong.
Your java applets are too amazing that I cannot help writing to you immediately.
Would you please mind telling me how you develop these kinds of programs and
the time needed to do so?
Actually, I want to develop similiar programs myself in Hong Kong.
You can contact me through my e-mail address swtkwan1 at
Thank you for your attention.
Stephen, W. T. Kwan 27/01/98



Subject: Pulley and more...
Date: Mon, 26 Jan 1998 20:57:05 -0600
From: "Radim Kolarsky" <rljc at>
To: <hwang at>
Dear Dr. Hwang:
Thanks for fixing the link and making the page available again.
I have been looking for a while for this type of an on-line physics textbook. Your page is just great.
Please keep up this good work. I work as a geologist/applied geophysicist at Shell in New Orleans.
Originally, however I was born in Czechoslovakia and came to the U.S as a political refugee in 1987.
I will never forget my high school physics professor (whose picture my wife and I keep on our web page)
I had there as a student. He did quite a bit for me.
Thanks again. SHould you efer come to New Orleans (a convention perhaps) please do not hesitate to let us know.

Radim Kolarsky

Subject: Pulley Experiment
Date: Sun, 25 Jan 1998 13:14:53 -0600
From: "Radim Kolarsky" <rljc at>
To: <hwang at>
Dear Dr. Hwang:
My son and I have enjoyed visiting your site today and yesterday, looking at your experiments.
In an effort to assembe information for my son's school science project,
we attempted to see the "Pulley" page but, unfortunately, the link is broken.
I have marked your site among my bookmarks and will definitely come visit again.

Radim A. Kolarsky

Subject: This site is so cool!!!
Date: Fri, 23 Jan 1998 16:10:28 -0600
From: Michele Gale-Sinex <gale-sinex at>
To: hwang at
Thanks for sharing it.
michele gale-sinex
center for integrated ag systems

Subject: Doppler effect and shock wave
Date: Sat, 17 Jan 1998 20:49:55 +0700
From: Amrat Chawla <amratc at>
To: hwang at
Dear Sir,
Even though I am in trading business, in my personal time I am very much interested in Physics
and I bought some 1st year university text book to study Physics as hobby.
But frankly, your web site give me a very clear lesson just in few days
that I discovered your site I understand a lot !!.
For example I try to understand the sonic-boom but even I read many time I still cant get it,
but with just few minute of virtual experiment with 'Doppler effect and shock wave' it became clear to me !!
Really thankyou very much for your site.
I regard you as my teacher.
With respect and best rgds.
Amrat Chawla



Subject: RC circuit applet
Date: Sun, 11 Jan 1998 06:41:16 +0000 (!!!First Boot!!!)
From: "Samara, Thomas Nick" <thomas.n.samara at>
To: hwang at
Dear Author,
Thanks alot for your program.
I couldn't quite find in the book a description of what the current was doing while the capacitor was charging.
Please make more programs like it.


Subject: Superposition of waves
Date: Mon, 15 Dec 1997 20:37:48 +0100
From: Peter Ryder <ryder at>
Organization: University of Bremen
To: hwang at
Your Java applet for superimposing wave is very nice,
but the "medium" has the interesting property that the group velocity and the phase velocity have opposite signs!
Well, that makes an intersting problem for the students to discuss.

Subject: standing wave
Date: Wed, 03 Dec 1997 10:26:03 +0000
From: Keli Sato <ksato at>
Organization: Addison Wesley
To: hwang at
Hello, I visited your Superposition Principle of Waves (
The applet is great, but I think you ment to say Standing wave, not Standarding wave

Keli Sato

Date: Sun, 26 Oct 1997 08:49:37 -0800
From: Ursula Sexton <usexton at>
To: hwang at
Hello, Mr. Hwang, I am an elementary science teacher,
as well as a leader in science education reform in the state of California.
I train teachers and while searching for some physics principles, I found the Web site with your applets.
I was interested in seeing your rainbow demonstration. It is so wonderful!
This site is just full of great demonstrations for clarifying principles that teachers just can't seem to grasp,
unless a visualization tool is provided. This is just great!
I thought I'd mention that there is a small mispelling at the bottom of your rainbow page.
Your last bullet reads: "Did yo noticed that rainbow consists of partially polarized light.
It should say - for grammar and spelling to be correct:
Did you notice that the rainbow consists of partially polarized light?
Best of luck in your journey to share with others the wonders of science.
Thanks for the gift of your knowledge and the wonderful medium to share it!
U Sexton



Subject: your educational Java applet(s)
Date: Mon, 20 Oct 97 17:53:34 -0700
From: Martin Koning Bastiaan <mjkb at>
To: "Fu-Kwun Hwang" <hwang at>
Dear Java Educational Applet Author,
Thanks for creating a great educational applet and making it available on the WWW.
Your Java applet is pointed to by the Educational Object Economy (EOE), located at
Apple Computer, Inc.零 EOE Team is preparing to distribute an EOE framework
(which we雹e calling the GOE--Generic Object Economy)
and its URL directory to groups who wish to set up their own EOE.
Please reply to this message if you would NOT like a pointer to your applet(s) (shown below) included in this release.
If you have written other educational applets in Java and would like to see them included in our EOE database,
please contact us. You can even enter your applets into our database yourself,
If you find any out-of-date or incorrect information, either listed below or on our site
(which contains more thorough descriptions of the Java applets than is listed here),
please let us know so that we may update our records.
For more information about the GOE:
Martin Koning Bastiaan,
Educational Object Economy

mjkb at

Subject: hotjava!
Date: Fri, 17 Oct 1997 13:19:20 +0000
From: David Johnson <djohnson at>
Reply-To: djohnson at
Organization: Douglas High School Science Department
To: hwang at
hello Fu-Kwun
I've used your vector addition and vernier caliper applets in my physics and physical sciences classes.

I'm just sending this note to thank you and ask you to keep up the good work!

Subject: Hallo
Date: Tue, 7 Oct 1997 00:29:04 +2.00
From: "H L Botha" <hermanb at>
Organization: Iscor Profile Products
Hallo Mr Hwang
I enjoyed your web site , good work !!
Herman Botha (South Africa)


Subject: pulley applet
Date: Fri, 26 Sep 1997 09:21:00 -0400
From: "Robert B. Muir" <bob_muir at>
Organization: Physics & Astronomy, UNC Greensboro
To: hwang at, bob_muir at
You have done a very good job developing these wonderful applets. at
I have not run all of them yet, but look forward to doing so.
I just tried the Pulley applet and had a problem. at
It seemed to download, but nothing ever appeared in the display area. at
The text below the display area looked ok. at
I am running Netscape Communicator 4.01 on a 166 MHz Pentium with 30 Mb of Ram. at
All the other applets I have tried worked ok.
Thank you for making this material available to us all.
Sincerely yours, Bob Muir
Physics & Astronomy
U North Carolina at Greensboro
Greensboro, NC USA

Subject: java and sound
Date: Fri, 12 Sep 1997 14:19:41 +0800
From: "Harlan W. Lefevre" <hwl at>
To: hwang at
Dear Dr. Hwang,
I have used several of your applets in my physics courses here.
And I asked our people to mirror your site here for fast access.
The applets are really useful. Thank you.
I usually roll an NCD Xterminal into my classroom and use a remote Sun as server.
Unfortunately java only writes audio to /dev/audio and Xwindows won't deliver the audio to the Xterm.
So the beauty of your Fourier Synthesis program is largely lost when one can't do the sound.
Do you have a solution to this problem?
Sincerely yours,

Harlan Lefevre

Subject: congratulations
Date: Sat, 06 Sep 1997 14:18:50 +0800
From: Cho-Teng Liu <ctliu at>
To: hwang at
Dear Prof. Huang:
Your web pages are very exciting and it deserves an award in education community.
A minor suggestion:
While watching some of the experiment, e.g. the RC充/放電 電路,
the browsers will be more comfortable if they can view both the figure and the text on the screen.
Therefore, I would like to suggest that
1) add a scroll bar for the text, or
2) place the title and figure on the left frame, and the text on the right frame. at
Congratulation to your accomplichment.


Subject: Your Physics Web site
Date: Wed, 03 Sep 1997 16:20:01 -0500
From: Narsing Rao <rao at>
Organization: Bethune-Cookman college
To: hwang at
Hello Dr. Wang:
at at at I just browsed your physics web site. I am really impressed by what I saw.
I am sure my students will find it very useful and exciting.
I am not a programmer either, and just now I am trying to learn about HTML and JAVA etc.

So long. I 'll be watching more of your pages.

Subject: EM wave Applet
Date: Mon, 01 Sep 1997 17:34:13 -0700
From: "Sunil K. David" <davids at>
Organization: Bethune-Cookman College
To: hwang at, rao at
Hi: You have made my job quite simple in showing the prop. of EM wave for my class.
Congratulations. Great applet. Goodluck, Bye,
Sunil K. David, M.Sc., M.Sc. Ph.D.

Assistant Professor of Physics

Subject: WOW! Great sight
Date: Fri, 29 Aug 1997 16:48:04 -0600
From: Gary S Smith <gssmith at>
To: hwang at
John P. Cise..Fac. Austin Com. College

Subject: Greeting
Date: Wed, 20 Aug 1997 16:29:26 -0500
From: "efra璯 barbosa" <ebarbosa at>
Organization: Yoshida-Barbosa
To: hwang at
Dear Prof. Hwuang:
I am also a physicist. I live in Bogota, Colombia.
I enjoy your simulations very much. It was a great work done by you. Congratulations!
Efraim Barbosa



Subject: Buoyance force
Date: Sat, 16 Aug 1997 07:09:52 -0500
From: "K. M. Isaac" <kmisaac at>
Organization: MM Enterprise
To: hwang at
Mr. Hwang,
Your buyancy force animation is very good. I plan to use it in my fluid mechancis course.
K. M. Isaac University of Missouri-Rolla



歡迎批評指教! 電子郵件請按 hwang at
at 者:國立台灣師範大學物理系黃福坤