Any science museum with a tall enough building loves to have one: A Foucault’s Pendulum. Usually set up around stairs or some other area where a cable can be hung from the roof to the bottom floor where a large weight is held. These pendulums swing back and forth (usually given a push by technicians in the morning) knocking over pegs as the day rolls by. But what about a smaller science museum? What about a college, University or even a high school? How can they set up some kind of Foucault’s Pendulum without some sort of huge building or drilling unwanted holes into the lecture hall floors? Scaled down versions with small weights don’t keep up the motion long enough – but with with a motorized system they can work.
This is where United Scientific’s Foucault’s Pendulum Apparatus comes into play:
Standing 57″ high and 16″ wide this Foucault’s Pendulum Device is perfect as a display or experimental equipment. It can sit in a lobby or in the classroom and operate over as a permanent display piece.
The case is durable steel with glass windows to prevent air currents from effecting the pendulum. This is needed at a small scale like this as Leon Foucault’s experiment used a 27kg pendulum bob on 67 meters of wire. Large enough to ignore most of the air currents in the Pantheon. But a device such as this needs the protection. In addition, the base is a heavy-duty vibration-damping with leveling feet so that foot traffic nearby will not effect the movement of the pendulum bob.
As mentioned, the pendulum bob is electrically operated so that air resistance will not slow down and stop the pendulum from swinging. The swing amplitude can be adjusted with a potentiometer.
Leon Foucault’s experiment is often misunderstood by many folks. Most assume that the pendulum will make a complete circle once every day (sidereal day, actually). But this is not really true except at the North & South Poles. There, the precession is as many expect – taking one (sidereal) day to precess fully around the circle. But as one moves down (or up) from the poles the effect of the coriolis actually is reduced. At the equator, for example the pendulum will not precess at all, while at 30 degrees from the equator the precession takes about 2 days. The number of days it takes to make a full precession is 360/(360*sin(latitude)). So in Philadelphia, at 40 degrees latitude (roughly) that figure is 360/(360*.64) or 360/231 or 1.56 days. Most people who see Foucault’s Pendulum at a museum will not be able to stay long enough to watch it make a complete precession – even if they had the patience, the museum remained open, and the pendulum was able to swing long enough on the ‘morning push’.
United’s Pendulum Apparatus features not only the durability features mentioned above, but also has a double-ended marker bar for precise measurements of the plane of swing when tracking the precession rate.
Whether used for a display or as a part of physics experimentation the Foucault’s Pendulum Apparatus is an excellent instrument at a very good price!
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