Block and tackle - effort required to raise a given weight


A block and tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift or pull heavy loads.The formula used to find the effort required to raise a given weight is:

Related formulas


Fathe force applied to the hauling part of the line (the input force) (N)
Lthe weight of the load (the output force) (N)
Nthe ideal mechanical advantage of the system (which is the same as the number of segments of line extending from the moving block) (dimensionless)
effmechanical efficiency of the system (equal to one for an ideal frictionless system; a fraction less than one for real-world systems with energy losses due to friction and other causes) (dimensionless)