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I just tried a few things out with some of our Vernier sensors and some play sand. While the moving sand definitely registered on both the Motion Sensor & the Photogate, the best graph was produced by using their Flow Rate Sensor. We poured the sand over the propeller to get the data. By retrofitting it with something more appropriate for sand, you could probably get even better data. Feel free to contact me off list if you've got any questions about the Vernier stuff.
David Perry | Lead Educator, Vernier Technology Lab
Oregon Museum of Science and Industry
Phone: 503-797-4585
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Date: Thu, 12 Apr 2007 15:39:21 -0700
From: Allan Ayres <[log in to unmask]>
Subject: Re: Radar guns
ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
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Phil wrote:
>We're trying to find a way to measure the speed of something like sand
>as it flows down an inclined plane. We were thinking of maybe trying a
>radar gun at the bottom of the plane pointed up at the sand, but we're
>kind of concerned about it...well, not working. Does anyone have any
>experience with this type of thing, or have any suggestions?
We're also looking for speed-sensors right now. In our case, we'd
like to gauge the speeds of steel balls rolling in tracks that are
right next to each other, so something that seems to be a feature the
vendors like to tout (wide-angle sensitivity) is actually a bug for
us. :-)
Plus, the cheap and easily available ones seem to be calibrated for
2-100 mph or so (the speed of golf balls, baseballs, go-carts, cars,
etc.), and our speeds would be significantly less than that.
Does anyone have any experience with Vernier's motion detectors?
http://www.vernier.com/probes/motion.html
They seem like total overkill for just getting a single number --
speed -- as opposed to graphing position and calculating acceleration
and everything else you can do with them, and they don't look
particularly promising in terms of angular discrimination (i.e.
returning the speed of just one ball). But, compared to some of the
industrial sensors, they're actually fairly inexpensive.
Hmmmmm.
Thanks for any insight,
--Allan
--
~~
Allan Ayres
Exhibit Developer
Lawrence Hall of Science
University of California, Berkeley
Berkeley, CA 94720-5200
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510-642-1254
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