在与学生的交流活动中,有学生提出这样一个问题:“用一水平力F拉着一物块M在粗糙的水平面上做匀速直线运动,这个物块的机械能守恒吗?”面对这个大家既熟悉又不易说清楚的问题,立刻引起了同学们关注.一部分学生认为,这个物块的动能和重力势能都没有发生变化,它的机械能总量也没 In the exchange activities with students, some students asked such a question: “With a horizontal force F pulling a block M to perform a uniform linear motion on a rough horizontal surface, is the mechanical energy of this block conserved?” Faced with this everyone Problems that were both familiar and difficult to explain clearly caught the attention of the students immediately. Some students believed that the kinetic energy and gravitational potential energy of this block did not change, and its total amount of mechanical energy did not change.