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Pulley system, demonstrating how pulleys facilitate the lifting of heavy weights (2004)
(upload.wikimedia.org)
A gun tackle has a single pulley in both the fixed and moving blocks with 2 rope parts dividing the load of 100N. The mechanical advantage is 2, requiring a force of only 50N to lift the load.
Author: César Rincón
Wouldn't it be 100, same as the mass being lifted (well more really, depending on the acceleration of that mass)?