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Re: Help!!An interesting acceleration graph



Can you reproduce this if you start the carts a little (like 25cm)
farther away from the motion detector? Are you using a sail on the
cart to make good, strong reflections? Or, have you played with the
aim of the motion detector?

I'm guessing that you're not getting a reflection from the same part
of the cart duing the whole travel. But, that's a guess, and so I
invite you to experiment. (I have no carts available.)

As you study this initial moment of the cart's motion, especially
looking at the velocity and acceleration graphs, remember that
MacMotion is doing a running average to find velocity and
acceleration (see Averaging... in the Collect menu) so that any
sudden changes are a bit rounded off. You can only change the
averaging *before* a data run, so seeing the effect of different
averagings means repeating the run.

If you want to look at brief time periods carefully, be sure you
increase the data collection rate. Motion will go up to 50
measurements each second.


JEG

To all:
My high school physics students have been looking at Newton's laws using the
Vernier Motion Detector and Force probe on the Macintosh Computer. We're
running Pasco Carts on their aluminum track and hanging a weight using their
super pulley. This should give us really nice graphs, but...

Our acceleration graph goes up, comes back down then levels off. eg, there's
a bit of a bulge, just as the cart is released. We're careful about hands
and other things that might interfere with the motion detector, but I have
no explanation for this. Has anyone seen this? Can anyone help?

arrgh

Don McQuarrie (not the chem text author)
Lynden High School
Lynden, WA 98264
MCQUARRD@LYNDEN.WEDNET.EDU
OR
MCQUARRD@PACIFICRIM.NET


-=================
John E. Gastineau
304 296 1966
Morgantown, WV
http://www.badgerden.com/~gastineau
email: gastineau@badgerden.com <==== NEW as of 10/1/96