Pick up a 10 lb weight with a rope or chain and swing it so you can feel the extra weight at the bottom of the swing. Now shorten the rope by half and try it again. The impulse is less, of course much faster reps and therefore the time during which the impulse is applied is much less - therefore less work is done. Now look again at his pictures. That pendulum has such a ridiculously short length it cannot possibly pump water on its own. The impulse time is too short to move the pump lever far enough. Anybody care to try the math? Robin
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