Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-L] Re: Ambiguous Question



I would choose A, because (1) a cup is a unit of volume, (2) the density
of the coffee decreases with increasing temperature, due to thermal
expansion, and (3) the density of the coffee increases (very slightly)
with increasing pressure, which corresponds to decreasing altitude.

Even if the identical collection of molecules of coffee is analyzed (as
opposed to the same volume of coffee) does the mass OF THE COFFEE change
due to changes in gravitational energy, or is it only the mass of the
Earth-coffee system that changes?

The kinetic energy associated with the collective motion of a system
doesn't affect the mass of the system, but the motion of the parts of
the system relative to the center of mass of the system affects the mass
of the system. Is the gravitational energy of the coffee similar also
an energy associated with a collective mode?

Daniel Crowe
Oklahoma School of Science and Mathematics
Ardmore Regional Center
dcrowe@sotc.org

-----Original Message-----
From: Forum for Physics Educators [mailto:PHYS-L@list1.ucc.nau.edu] On
Behalf Of David T. Marx
Sent: Thursday, November 17, 2005 9:58 AM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: [PHYS-L] Ambiguous Question

<snip>

In which one of the following situations does a cup of coffee have the
greatest mass?
A. when its temperature is 60 F sitting on a table at sea level
B. when its temperature is 95 F sitting on a table at sea level
C when its temperature is 95 F sitting on a table in a mountain cabin
D. when its temperature is 60 F sitting on a table in a mountain cabin

After the majority of students selected choice A....

<snip>
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu
https://www.physics.buffalo.edu/mailman/listinfo/phys-l