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Re: Graphing d vs t



At 10:23 AM 11/12/01 -0400, you wrote:
While at the NSTA conference in Columbus, on Friday at
one session one teacher was adamant about when
graphing distance vs time, time was ALWAYS on the
horizontal axis...

The teacher is entitled to be adamant, in order to have
everyone looking at the page from the same point of view,
in other words, there is a bit of classroom control behavior
spilling over here. I would not have reacted to it.

I thought it depended upon what was
being controlled. If I control time and measure distance,
then time is on the horizontal axis but if I control
distance and measure time than distance should be on
the horizontal axis. Any thoughts?

You bet! The topic is usually some aspect of motion where
the behavior is most often described using a time referenced
(rate) of change of position, or velocity, or acceleration (jerk).
In order to have these easily apparent from viewing the slope of
a plot, and also not depart from the notion of rise/run, the time
axis must be horizontal.

If the "Math" (or other) influence delves deeply into causal or
dependency relationships and works this unnecessary distraction
into this discussion, what are we to do if the original data table
came from the ultrasonic motion probe? In this case, even the distance
is based on a time reference, but does the beginning student need to
even worry about this? If THIS comes to a vote, I would favor the
notion that the slope of the graphed information be useful -- in fact,
I would have no other reason to plot the data.

Tom Ford



Tim O'Donnell