Sunday, April 03, 2011

C is for centripetal

Centripetal force, as opposed to its counterpart, centrifugal force, as best I can recall is defined as the center-seeking force in a rotating system. I was never able to make any sense of this, as the man in the locally-filmed science show spun milk in a bowl to demonstrate how it would flee from the center, making a ring, a torus, a three-dimensional body with a single hole. The man would try to explain that centripetal force in this system was represented by the sides of the bowl, but I could never understand how that was an internal force and not an external, imposed constraint. It was the centrifuge that I could understand, the impulse to flee, even as I was told that centrifugal force was an illusion. It didn’t exist. There was nothing pushing the milk from the center of the bowl. It was much later that I learned about inertia and the attraction of the void. Nothing is a force of its own.

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