Pulley System Mechanical Advantage

Theoretical and actual MA across fixed/movable/block-and-tackle rigs.

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Formula and source

Theoretical MA = number of supporting rope segments. Actual MA = theoretical × pulley_efficiency^n_pulleys. Fixed pulley redirects but does not multiply force; movable pulley × 2; block-and-tackle = 2n for n sheaves.

Classical mechanics; NFPA 1006 / 1670 by name for rescue context.

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