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]

Re: Weight and Mass



At 12:05 PM 9/24/01 -0500, Tina Fanetti wrote:
I thought I had explained clearly what the difference between weight and
mass was to my students. I asked them to write down any questions they
had at the end of class and some one wants me to explain the difference
again with examples.

Then at 12:19 PM 9/24/01 -0500, Joseph Bellina wrote:
If only one person asks, or even if only a small fraction asks, I would
comment on the question and suggest they see you. If more than a third
are asking, then I would spend class time on it.

I wouldn't assume that.

It could well be that if _one_ of them has the nerve to ask, there are
_ten_ who are just as confused (maybe more confused) who didn't ask.

The class in question has a bad track record on asking questions, so unless
and until there is a deluge of questions, I suggest giving every question
the royal treatment. (Of course one should cull out some questions as
being blatantly inappropriate, but this question isn't one of them, not by
a long shot.)

=====================

In the context of
weight = the gravitational force on an object due to Earth

mass = the quantity of material present in a sample; fundamentally
related to the number of atoms in the sample


At 12:29 PM 9/24/01 -0500, Tina Fanetti wrote:
Funny, That is what I told them..they didn't get it

Not completely surprising. This is a theorist's answer. It assumes they
have a notion of what gravity is, and a separate notion of what "quantity
of material" means, and/or what "number of atoms" means.

Try the experimentalist's answer, such as:

At 01:21 PM 9/24/01 -0700, kowalskil wrote:
My mass on the moon is the same as on earth but my
weight there is not the same.

In particular, get video of astronauts hopping around on the moon.

Similarly, perhaps better, get video of astronauts zooming around,
weightless, in the space station. They've still got mass; they don't
accelerate unless you push them, and the acceleration is still inversely
proportional to the mass.