VV (3) - The Clock

[David Morris]

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(46) The pendulum didn't swing back and forth but was in the form of a disc, 
parallel to the floor and driven by a shaft
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This pendulum moves very much like a yo-yo:  It reverses the direction of 
its rotation, reaching the stopping point (does it ever really stop?), the 
"zero" of momentum, only to be pulled back by that invisible hand.

Both pendulums and yo-yos require the application of an outside force for 
their continued movement.  Old-time pendulums were powered by a weight on a 
rope or chain pulling down, resisted by the clock's mechanisms.  Some human 
hand had to crank the lever to raise that weight.

Yo-yos, like pendulums, harness momentum and apply a small amoout of extra 
force to keep things rolling.

Momentum works.  Try stopping a moving train.  But put a train on a chain 
and start it swinging.  Just a little extra push at the zero-plus of each 
swing will keep that big mass moving.  Did somebody mention harmonic motion?

David Morris
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