National flag lifting platform principle courseware

    In the pulley teaching of current junior high school physics textbooks, using the equivalent lever principle of pulley to demonstrate experimental facts is a good teaching material, which deepens students' connection and understanding of knowledge. In order to make teaching and learning proceed closely and synchronously, we have developed the lever principle demonstrator of pulley in teaching, which is now introduced to you. I. The design idea shows its equivalent lever in kind on the actual pulley.

Objective: because the pulley and lever are equivalent in terms of their effect, the working principle is also the same, there are fulcrum, power, resistance, power arm, resistance arm, etc., and pulley and lever are simple machinery, all follow the principle of work, however, the fulcrum of the pulley sometimes moves on the shaft, sometimes on the wheel, or even sometimes, with different shapes. But its effect is equivalent, so the pulley is also a lever.

1. Experiment preparation know experimental apparatus: fixed pulley, base, pole, drawstring, flag.

Experiment report:

fixed pulley of central shaft cannot be fixed. The function of fixed pulley is to change the direction of force, but it cannot save effort. When pulling heavy objects
, you can use fixed pulley to change the direction of force application to the direction that is easy to output. When using fixed pulley, the distance of force pulling is equal to the distance of the object rising, which cannot save effort or effort. The pulling force at both ends of the rope is equal, so the output force and input force, without friction, the mechanical efficiency of fixed pulley is close1.