PulleysPulleys

VocabVocab

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VocabVocab A A PulleyPulley is a wheel with a grooved rim in is a wheel with a grooved rim in

which a rope can run to change the which a rope can run to change the direction of the pull (force) that lifts a direction of the pull (force) that lifts a load.load.

A A fixed pulleyfixed pulley has a wheel that is has a wheel that is attached to something above the load.attached to something above the load.

A A movable pulleymovable pulley has a wheel that is has a wheel that is attached to the load.attached to the load.

Mechanical advantageMechanical advantage reduces the reduces the effort (force) needed to lift a load or effort (force) needed to lift a load or overcome a resistanceovercome a resistance

Directional advantageDirectional advantage is a change in is a change in direction that results from passing a rope direction that results from passing a rope through a pulley.through a pulley.

PULLEYSPULLEYS The greater the number of ropes The greater the number of ropes

supporting the load, the less effort supporting the load, the less effort needed to lift the load.needed to lift the load.

The effort needed to lift a load can be The effort needed to lift a load can be predicted from the weight of the load and predicted from the weight of the load and the number of ropes supporting the load.the number of ropes supporting the load.

The benefits gained by using simple The benefits gained by using simple machines are always balanced by costs. machines are always balanced by costs. When the benefits outweigh the costs, When the benefits outweigh the costs, the machine is a useful tool.the machine is a useful tool.

In a pulley system, a reduction in effort is In a pulley system, a reduction in effort is balanced by the distance over which the balanced by the distance over which the effort must go. You must pull a further effort must go. You must pull a further distance, but you use less effort.distance, but you use less effort.