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滑轮组的机械效率是初中物理的重点内容,它的计算关键在于正确判断有用功和总功.有用功是指通过机械为达到某种目的而做的功.具体地说:当利用机械提高物体时,用来提高物体的功是有用功,W_有=G_物 h.当利用机械将物体沿水平方向匀速拉动时,用来克服物体受到的水平阻力而做的功是有用功,W_有=f_阻·s.而总功是指人们在利用机械时,作用在机械上的动力对机械做的功,W_总=F_动·s.机械效率
The mechanical efficiency of the pulley block is a key part of junior high school physics. The key to its calculation lies in the correct judgment of useful work and total work. The useful work refers to the work done by the machine to achieve a certain purpose. Specifically: when using a machine to raise an object , Used to improve the work of the object is a useful work, W_ = G_ object h. When the use of machinery to move the object along the horizontal uniform speed, the work done to overcome the horizontal resistance of the object is done is useful, W_ There are =f_resistance·s. And the total work refers to the work done by people on machinery when they use machinery. W_total=F_moving·s.mechanical efficiency