Block and Tackle

Principles of Science: Mechanical Advantage, Work

Lift heavy objects using a block and tackle and experience how the force and distance required to lift the objects changes as different numbers of pulleys are used.

A block and tackle is a simple machine consisting of a two sets of pulleys connected using rope. One set of pulleys hangs from a ceiling or stand while the other connects to the object being lifted. The rope wraps around the multiple pulleys; the operator pulls on the loose end.

The weight of the object being lifted is supported be each strand of rope. Since the rope wraps around the pulley many times, the operator needs to supply a small force to lift the object. Once again, smaller force means greater distance. In other words, the user needs to pull a lot more rope through the block and tackle than the distance the object is being lifted.

A block and tackle is often found at construction sites.