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机械效率是初中物理力学部分的重点内容,也是困扰学生学习的难点之一.初学物理的同学根据公式η=W有用/W总,求出机械效率后,往往把它作为定值,而导致解题出差错.认识影响机械效率变化的因素,对综合分析计算有关机械效率的习题很有帮助.下面就用滑轮组、斜面对物体做功情况来说明机械效率的变化.
Mechanical efficiency is a key part of the physics and mechanics part of junior middle school, and it is also one of the most difficult problems for students to learn. Beginner physics students according to the formula η = W useful / W total, after determining the mechanical efficiency, often as a fixed value, resulting in the solution Errors are identified. Knowing the factors that affect the change of mechanical efficiency is very helpful for comprehensive analysis and calculation of mechanical efficiency problems. The following describes the mechanical efficiency changes with pulleys and oblique objects.