Differential pulley the system becomes a simple "gun tackle" with a mechanical advantage of 2. The same principle is used in a differential windlass, where the connected pulleys are replaced by winches. In the above graphic, the four segments of the chain are labelled W, X, Y and Z. The magnitudes of their corresponding forces are "F", "F", "F" and "F", respectively. Assuming that the chain is massless, "F" = 0 because segment X is not supporting any weight. Taking the system at equilibrium, "F" and "F" are equal — if they were not, the lower pulley would freely turn until they
Hook (Once Upon a Time) memories. Upon recalling what Emma did to him, Hook immediately renews his plot to revive every Dark One and kill Rumplestiltskin. However, after a confrontation with Emma and Regina, Hook has a crisis of conscience and turns on the Dark Ones. Subsequently, Hook sacrifices his life to destroy the Darkness once and for all. However, upon the discovery that Gold has betrayed Hook to take back his power, Emma blackmails him into helping her get into the Underworld, so that she may launch a mission to revive him. In the Underworld, Hook is tortured by Hades. However, with the help