From: kowalskil@mail.montclair.edu
Subject: Fwd: A RESEARCH PROJECT (AND A GOOD LAB)
Date: September 9, 2005 2:43:21 PM EDT
Last night I posted this message:
From: kowalskil@mail.montclair.edu
Subject: A RESEARCH PROJECT (AND A GOOD LAB)
Date: September 9, 2005 12:36:18 AM EDT
To: PHYS-L@LISTS.NAU.EDU
Reply-To: PHYS-L@list1.ucc.nau.edu
Several minutes later I received this message, as other subscribers, I
suppose.
But I also got a message whose beginning was as follows:
From: LISTSERV@list1.ucc.nau.edu
Subject: Rejected posting to PHYS-L@LISTS.NAU.EDU
Date: September 9, 2005 12:35:54 AM EDT
To: kowalskil@mail.montclair.edu
Your message is being returned to you unprocessed because it appears
to have
already been distributed to the PHYS-L list. That is, a message with
identical
text (but possibly with different mail headers) has been posted to
the list
recently, either by you or by someone else. If you have a good reason
to resend
this message to the list (for instance because you have been
notified of a
hardware failure with loss of data), please alter the text of the
message in
some way and resend it to the list. Note that altering the "Subject:"
line or
adding blank lines at the top or bottom of the message is not
sufficient; you
should instead add a sentence or two at the top explaining why
you are
resending the message, so that the other subscribers understand why
they are
getting two copies of the same message.
There is a chance that the message was sent to me only. For that reason
I am reposting it.
Please delete this message if you already received it yesterday.
A GOOD LAB FOR ALL AND A RESEARCH PROJECT FOR SOME
1) THE INVITATION BELOW (in lower case text) WAS POSTED IN AUGUST WHEN
MANY OF YOU WERE PROBABLY AWAY. ONLY TWO PEOPLE MADE COMMITMENTS TO
PERFORM THE SUGGESTED EXPERIMENT (ONE WITH TWO STUDENTS AND ONE WITHOUT
STUDENTS). IT IS NOT TOO LATE TO MAKE A COMMITMENT.
3) I DID NOT REALIZE THIS IN AUGUST BUT IT IS NOW OBVIOUS THAT THE
FRENCH SETUP IS SUITABLE FOR A STUDENT LAB IN PHYSICS OR CHEMISTRY. NO
SPECIAL ELECTRODES OR HIGH VOLTAGE POWER SUPPLY IS NEEDED -- ONLY
ORDINARY WATER AND AN IMMERSION HEATER. BY USING THE SETUP OF FIGURE 1
(WITH AN OHMIC HEATER ONLY) STDENTS WILL COLLECT DATA TO TRACE THE PINK
CURVE (SEE FIGURE 2). THEN THEY WILL TURN THE ELECTRIC CURRENT OFF AND
COLLECT THE TEMPERATURE-VERSUS-TIME DATA. FROM THAT CURVE THEY WILL
DETERMINE THE AMOUNT OF THERMAL ENERGY LOST IN 5 MINUTES DUE TO
CONDUCTION, CONVECTION AND RADIATION. ASSUMING HEAT LOSSES BY THESE
THREE MECHANISMS NEAR 95 C ARE NOT VERY DIFFERENT FROM THOSE AT 100 C,
AND KNOWING THE HEAT LOSES BY ALL FOUR MECHANISMS, STUDENTS WILL BE
ABLE TO SHOW THAT L IS INDEED CLOSE TO 2260 J PER GRAM.
HERE IS A NUMERICAL ILLUSTRATION BASED OF FIGURE 2: (P=400 W TIME=5
MIN, ENERGY=400*5*60=120,000J). THE AMOUNT OF WATER EVAPORATED IS 36
GRAMS. BUT THE ENERGY USED TO EVAPORATE THAT AMOUNT IS LESS THAN
120,000 J BECAUSE ONLY PART OF ELECTRIC ENERGY WAS USED ON EVAPORATION.
SUPPOSE WE KNOW THAT 40,000 J IS LOST IN 5 MINUTES VIA THREE OTHER
MECHANISMS. THEN
L = (120,000-40,000)/36 = 2222 J PER GRAM
4) THIS MIGHT ALSO BE A GOOD PROJECT FOR THE ANNUAL AAPT APPARATUS
COMPETITION.
LUDWIK
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
= = = = =
Dear colleagues:
Please read what has just been posted at my website as:
It is an invitation to participate in a collective student-oriented
project. The idea of turning what I wanted to do into a collective
Internet project was prompted by the ongoing debate about scientific
methodologies. Give your students a chance to participate in a research
project they can easily understand.
P.S.
Comments on this list (in addition to private messages would be
appreciated).
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
= = = = =
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu https://www.physics.buffalo.edu/mailman/listinfo/phys-l