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WoP #1: Jelly Cat




So, I went to RIT for a college visit not too long ago, and they played the above (slightly goofy) video about creating perpetual (never ending) motion by combining two principles derived from urban legends. The first is that a cat, dropped from any height, will always land on its feet, and the second is that a piece of toast with jelly on it will always land jelly-side down. The video goes on to state that, by spreading jelly on a cat's back, the cat will be unable to land both on its legs and jelly-side down, and will spin indefinitely. The video goes on to state that this could be used to power a train system by using the cats as a form of wheels. Unfortunately, there are several things wrong with this videos "theories."

First of all, the mass of the jelly is on a much smaller order of magnitude of that of the cat. As such, the mass of the jelly would move the cat's center of mass a noticeable amount, meaning any forces acting on the cat-jelly system should still have the same effect as those acting on an un-jellied cat. Assuming a cat will always land on its feet, this means that even a jellied cat will always land on its feet, and the jelly will not have affect that in the slightest.

Second, assuming the cat would enter a state of perpetual motion, using it to move a train would still be impossible. In order to move a train, the cat would have to apply some force to the train, and the train would therefore have to apply some force to the cat. Assuming this is the case, the cat would likely have a normal force acting on it from the train, and therefore, a force of friction. As such, considering the mass, and by extension, weight of the train (which would be part of the normal force), the force of friction (which opposes motion) would likely be of a much greater magnitude than any other forces acting on the cat, and, therefore, the cat would be decelerated until it eventually reached a stop. Therefore, it would be impossible to use a cat to power a train system.

Finally, the weight of the train would crush the cat. Why doesn't anyone want cats to live?


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