运用动能定理解题中常见错误原因分析

通过对运用动能定理解题时常见的错误原因主要是理解上和概念性的错误。应注意的问题一是计算功时除必须注意其正、负号外，还应注意内力所做的功，在计算动能时，必须用相应的绝对速度来表示；二是如果我们用动能定理的微分形式求加速度时，需列出任意瞬时系统的动能及元功的表达式；三是势能的计算应明确势能是相对于给定的零势能位置而定的。

Cause Analysis on Common Errors in Application of Driven Gear Theorem into Problem Solving

The common errors in application of driven gear theorem into problem solving lie mainly in the understanding and misconception. By analyzing the causes, the author should concern that： 1. while calculating the active power, the researcher should pay attention to the power from internal power apart from the positive and negative signs; while calculating the power energy, we should express it with the definite speed. 2. If we testify the acceleration with the differentiation, we should list the expression of power energy and meta - power. 3. The calculation of potential energy should make it dear that potential energy is decided by the given zero potential energy location.