Re: "all accelerations are 9.8m/s^2"

[John Denker <jsd@MONMOUTH.COM>]

At 11:36 PM 1/25/01 -0500, Hugh Haskell wrote:
> every year a certain fraction of my students complete the course thinking
> that "all accelerations are 9.8 m/s^2! It really makes for some
> interesting answers to problems.

Innnnnteresting.  That throws quite a dramatic light on the situation.

It seems to me this more to do with basic logic than with gravitation in
particular, or physics in general.

Specifically, it seems the students in question are missing the crucial
distinction between
  a) there exists some acceleration equal to 9.8m/s^2
  b) each and every acceleration is equal to 9.8m/s^2

Formally this is called First Order Logic.
  http://www.bestweb.net/~sowa/misc/mathw.htm#Predicate

I would have hoped that all students would have mastered this distinction
long before starting high-school physics.  Apparently this is true in some
places, where logic and set theory are introduced in 5th grade
  http://boston.k12.ma.us/textonly/teach/mathcurric.asp
but not in other places,
  http://www.nknox.k12.in.us/nkmath.htm
where logic and set theory are not mentioned until 11th grade or so.

(This is an example of what I call "same planet, different universe".)

If physics students don't understand this, there's a big problem, and no
amount of talking about masses or forces or fields or 4*pi*epsilon_0 will
solve the problem.  The physics teacher will just have to take time out and
conduct a mini-course in elementary logic.  Sigh.