Who can summarize the junior high school physics inside about the pulley block, the lever aspect knowledge? Better be more detailed
Under the action of force, if a hard rod can rotate around a fixed point, it is called a lever. In life, according to needs, the lever can be made straight or curved. The fixed pulley is an equal arm lever, the movable pulley is a kind of lever, and the power arm is twice of the resistance arm. The condition of lever balance: power x power arm = resistance x resistance arm or