动量定理和质心运动定理的比较教学

COMPARISON TEACHING OF MOMENTUM THEOREM AND CENTROID MOTION THEOREM

正确运用质心运动定理的关键在于对质心概念的理解和质心加速度的确定.教学中学生容易将质点系中某运动点的加速度等同于质心的加速度从而导致分析结果的错误.本文结合一旋转电机动力学问题的求解,阐述在动量定理和质心运动定理教学中应注意的问题.

The key point to apply the centroid motion theorem correctly is the understanding of the concept of centroid and the determination of centroid acceleration. During the teaching, students may think that the acceleration of a moving point in the system of particles is equivalent to the acceleration of centroid, which leads to wrong analysis results. In this paper, by solving the dynamic problem of a rotating machine, we discuss the problems needing atten- tions in teaching of the momentum theorem and centroid motion theorem.