在动力学中,连结体问题一直是困扰学生的难题。牛顿第二定律的拓展公式,由于不涉及系统的内力,因而可以很巧妙地用来处理不涉及内力的连结体运动问题。 1．拓展公式的推导设有两个质量为m_1、m_2物体,分别受到外力F_1、 F_2的作用,相互间的作用力为F_21和F+12,加速度为a_1、 In the dynamics, the problem of connecting bodies has always been a problem that puzzles students. The expansion formula of Newton’s second law, because it does not involve the internal forces of the system, can be used very skillfully to deal with the problem of joint movements that do not involve internal forces. 1. The derivation of the expansion formula has two masses m_1 and m_2, which are affected by external forces F_1 and F_2 respectively. The force between them is F_21 and F+12, and the acceleration is a_1.