动能定理反映了物体动能的变化与引起变化的原因——力对物体所做的总功之间因果关系.合外力对物体做正功则物体动能增加,且做了多少正功动能就增加多少;合外力对物体做负功则物体动能减少,且做了多少负功就减少多少动能.如果物体在运动过程中所受到的合力先对 The kinetic energy theorem reflects the change in the kinetic energy of the object and the cause of the change—the causal relationship between the force and the total work done by the object. When the external force does positive work on the object, the kinetic energy of the object increases, and how much positive work kinetic energy is done increases When the external force does negative work on the object, the kinetic energy of the object is reduced, and how much negative energy is done to reduce the amount of kinetic energy. If the object is subjected to a total force during the movement