Date: Mon, 20 Feb 2012 10:41:14

Author: --- "David Sturm"

Subject: Re: kilonewtonman

Post:

tap-l@lists.ncsu.edu writes:
>Can this teaching method lead to student confusion between force and mass?

Bill: I'm usually finding it doesn't.... because when Kilonewtonman goes into space, he loses
his Kilonewtonman powers. I imagine he becomes Micronewtonman in Earth orbit??
On the 'surface' Sirius B, I think he'd become Meganewtonman?

Seriously(?) though.... I "pound" into them that my mass is 100 kg, and my weight is 1000 N,
and use it repeatedly through the first six weeks of the semester. I think that the average
calc-based course doesn't repeat these things that are basic to us after the first lecture.
That's probably a big part of the problem we see with force/mass confusion. We assume
all our students are immediate experts, when we're the first person to probably enforce(!?)
the difference in a way that matters to the solution of problems.

I also always bring in a 1-liter of Diet Coke to drink from, which of course has a mass about 1 kg,
and a weight of 10 N, so there are always units being thrown around.

I appreciate David K's suggestion of the McNewton (was that you, DK?)... now I have
something to eat as I drink my liter of soda. I wonder if fries are centinewtons....

My first undergrad thermodynamics courses were taken in the mechanical engineering
department, and I checked ours here. Considering many of the texts use lbm and lbf
side by side, just as they did 30 years ago... I'm not sure we'll ever eliminate student
confusion between force and mass.

'Slug'gishly on a Monday,
David

**32d UMaine Physics Teachers Mtg: March 9, 2012
====================================================
David E G Sturm - sturmde@maine.edu - 1.207.478.4937 (cell)
--Physics & Astronomy Instructional Labs --ATOMIM Board
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