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? fixed pulley

Fixed pulley features: no effort, but can change the direction of the power. (Essentially an equal arm lever).

Definition: a pulley with a fixed shaft in the middle.

② Essence: the essence of the fixed pulley is: equal arm lever

③ Features: The use of fixed pulley can not save effort but can change the direction of the power.

Movable pulley

Pulley characteristics: save half the force, but can not change the direction of power, to cost distance. (Essentially, the power arm is twice the lever of the resistance arm)

Definition: a pulley that moves with a heavy object. (Can move up and down, can also move left and right)

② Essence: the essence of the pulley is: the power arm is 2 times the labor-saving lever of the resistance arm.

③ Features: The use of pulley can save half the force, but can not change the direction of the power.

Pulley block

Block: When a block is used, the block uses several lengths of rope to lift the object, and the force used to lift the object is a fraction of the weight of the object.

1, definition: by a number of fixed pulley and movable pulley matching.

2, features: can save effort, can also change the direction of the force. With a pulley block, there are several lengths of rope to lift the object, the force used to lift the object is a fraction of the weight of the object.