自己拉自己

        操作过程： 

        ①一组立式安装的定、动滑轮组：参观者坐到座椅上，拉着眼前垂下的绳索，很勉强地将自己拉起来。   
        ②二组立式安装的动滑轮组：参观者坐到座椅上，拉着眼前垂下的绳索，发现很容易地就把自己拉上去了，反应了动滑轮越多越省力的原理。    

Tug of war

        Static and moving pulley This exhibition displays the mechanics  principle of the static pulley can change the dint way,and the moving pulley can province half dint. 

       Operation process:
       ①A suite of static and moving pulleys installed for standing: visiters  sit on the chair, pull the rope that droop in front of eyes, pull himself up difficultly.
       ②Two suites of static and moving pulleys installed for standing: visiters sit on the chair,pull the rope that droop in front of eyes,discover that pull himself up very easily,responding the principle of the more moving pulleys, the more labor-saving.