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替代法是一种特殊的思维方法。在解题过程中出现已知条件不确定,或者题设条件数多于所列物理方程个数等情况时,努力寻找式中的相同因子,进行相互替代,这种方法往往能使堵塞的思路畅通,使问题迎刃而解。现举解2005年高考物理试题两例。例1 [天津卷题24]:如图所示,质量m_A为4.0kg的木板A放在水平面C上,木板与水平面间的动摩擦因数μ为0.24,木板右端放着质量m_B为1.0kg的小物块B(视为质点),它们均处于静止状态。木板突然受到水平向右的12N·s的瞬时冲量I作用开始运动,当小物块滑离木板时,木板的动能E_M为8.0J,小物块的动能为0.50J,重力加速度取10m/s~2,求
Alternative law is a special way of thinking. In the process of solving the problem, when the conditions are known to be uncertain, or if the number of conditions is higher than the number of listed physical equations, etc., the same factors in the formula are searched for and replaced by each other. This method can often make the idea of blockage. Smooth, solve the problem. Two examples of physical examination questions in the 2005 college entrance examination are presented. Example 1 [Tianjin Volume 24]: As shown in the figure, a wooden board A with a mass m_A of 4.0 kg is placed on the horizontal plane C, the dynamic friction coefficient μ between the board and the horizontal plane is 0.24, and the mass m_B 1.0 kg is placed on the right end of the board. Block B (as particles), they are all stationary. Suddenly, the board is suddenly moved by the instantaneous impulse of 12N·s horizontally to the right. When the small object slides off the board, the kinetic energy E_M of the board is 8.0J, the kinetic energy of the small object is 0.50J, and the acceleration of gravity is 10m/s~2. ,begging