Re: g

[scott <sgoelzer@EARTHLINK.NET>]

on 9/10/01 2:57 PM, Kossom at MKossover@NEWMANSCHOOL.ORG wrote:

snip
> In class, thus, I do not speak of the acceleration due to gravity as -9.8
> m/s/s, but rather as 9.8 m/s/s downwards. It may be negative or positive
> depending on how the problem is set up.

I know in Giancoli physics down is usually neg. and the only reason I can
find is that the standard coord system "down" is neg.

I agree with that it is better to describe that gee is down rather than
pos/neg. and find it interesting that my students are more willing to change
the sign of acceleration than velocity.
I usually take it to mean that they have no clear mental picture of
acceleration and therefore do not mind acceleration being negative, but they
do picture velocity and have trouble with the magnitude vs. direction
meaning of a sign.

Defining gee as 22 mph added downward per second in freefall is more real
than 9.8 m/s^2 (what's a square second anyway?)




*****************************
S.Goelzer
Physics Teacher
Coe - Brown Northwood Academy
Northwood NH 03261
603-942-5531 ext43
sgoelzer@coebrownacademy.com
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