? 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.
