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Re: Smart PASCO Pulley



The max data rate for the smart pulley is 25 Hz. There are 8 spoke per
revolution, so the max angular speed is (25/8) rev/sec. Much faster than
this, and your data is garbage. Your sign change sounds like a 'strobe'
effect.
OK...the smart pulley is limited even though the interface is capable of
much faster data collection.

sign. The smart pulley does not have a direction encoder. This device
only measures the times from light blocked to light unblocked. Knowing

Agreed. This Science Workshop displays any detected decline in angular
speed (assumed to be positive angular velocity) as a negative
angular acceleration. This is an arbitrary designation to facilitate
consistent graphing (no problem there).

There appears to be no problem during larger changes of velocity. I
tried this at a variety of sampling rates with similar results (above
and below the 25 Hz).

Data does confirm the strobing effect you indicated. When rotation
drops to 2-rotations per second (of the smart-pulley) the acceleration data
shows *much* better resolution of the acceleration data (especially important
for the smaller acceleration observed during a free "spin down in this case).

Thanks.

--

Timothy C. Burgess, Truck Driver
Science in Motion Project
Physics Department, ILB 35
University of South Alabama
Mobile, Alabama 36688

Work: (334)-460-6224
Home: (334)-432-3024

tburgess@jaguar1.usouthal.edu