牛顿第三定律告诉我们:两个物体之间的作用力和反作用力总是大小相等,方向相反,作用在同一条直线上.因此,不少学生认为作用力与反作用力所做的功都是正功或都是负功,并且一定相等.其实不然,下面举例进行分析:一、作用力和反作用力可能都做正功图1中,在光滑的水平绝缘面上,有两个大小相 Newton’s third law tells us that the force and reaction force between two objects are always equal and opposite, acting on the same straight line. Therefore, many students believe that the work done by both the acting force and the reaction force is positive. Work is either negative work and must be equal. Actually not, the following examples are analyzed: First, the force and reaction force may do positive work. In Figure 1, in the smooth horizontal insulation surface, there are two sizes.