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Scott,

might not be what you are looking to achieve, however

like Galileo I'd suggest you could run the experiment on an inclined plane.
have the ball on a track ( pair of rails etc), with the ball captive between the rails.
Have a finger slot to allow them to push it up hill, and release.

having it on the slope slows it all down, so your sensor system has a bit more 
precision ( ultrasonics are good, bit can be a little slow - sound only goes so fast).

It also means the ball is held in a very defined path so your sensors don't have to deal with the ball following different
paths on each bounce.

I;ve seen and used a range of sensors. video capture could work with a bright coloured ball as target, but 
with simple cameras you're limited to 25/30 fps, ( so in a 0.5 meter drop you'd get around 8-10 samples) so you might need to run it on a ramp to slow it down and get enough points.

parallax ping ultrasonic sensors are faster and you might get 50 to 100 samples a second.
there are some good cheap optical range sensors that would work at about 100 plus samples a second, but not on a steel ball.

and you could run a set of photo gates.

if you used a steel ball ( and steel plate to bounce it off), you could use and electromagnet ( either fixed or slidable along the track) and use the 
release of the electromagnet to sync/start  the data capture.


Just some thoughts.

Stuart Kohlhagen
Director Research and Development
Questacon
The National Science and Technology Centre
Canberra




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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We are considering developing an exhibit activity where visitors bounce
balls and see the bouncing motion graphed in real time. The goal of the
activity would be for the visitors to use the mathematical
representation of the motion to compare how different types of balls
bounce.

Has anyone developed or seen an exhibit related to this? We are
especially interested in how others have dealt with the issue of loose
versus contained balls. Loose balls are a nightmare but a mechanical
reset option might be equally as challenging.

Thanks for your help!

Scott


Scott Pattison
Senior Exhibit Developer
Oregon Museum of Science and Industry
1945 SE Water Ave
Portland, OR 97217
503.797.4673
[log in to unmask]
www.omsi.edu

 
 
Crack the Case - CSI: The Experience now on exhibit May 23-Sept. 15


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