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Re: [Phys-l] data manipulation -- analysis



You seem to be inferring pendulum speed by timing the passage of an
optical blade at the nadir.
If this method is too noisy for your purpose (you go on to subtract the
n+1 speed from the n swing speed to fit a delay curve) I am suggesting
you optically read a scale attached to the pendulum and relate THAT
signal frequency to the pendulum's speed. That will certainly provide a
less noisy speed measure.

Brian W

On 4/7/2012 11:52 AM, Bernard Cleyet wrote:
On 2012, Apr 07, , at 09:23, brian whatcott wrote:

Sounds like you are a captive of your measurement method, bc. Another
approach to optical speed sensing of a pendulum which would reduce the
noise contribution is applying a stripe strip to the optical blade; then
the variable frequency output could be tracked with a VCO or a frequency
discriminator arrangement.

Brian W

Please explain (more detail).


bc puzzled

p.s. My original question was when to do averaging, early or late -- seemed obvious in the case of averaging the energy, i.e. average the squares, not square the speed averaged. But what to do with the times. Average the times then invert or invert then average?
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_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l