【摘要】 本文阐明应用动量矩定理如以平面运动物体的速度瞬心为矩心，则矩心速度应取速度瞬心沿 固定瞬心轨迹的速度（不等于零）．本文直接导出了有关各项公式，从而澄清了基本概念．更多还原

【Abstract】 This paper expounds that if the instantaneous velocity center of a rigid body in the plane motion are taken as moment center, by applying the theo- rem of moment of angular momentum, then the velocity of moment center should be the instantaneous velocity of the center (not equal to zero) along the fixed trace of instantaneous center. Herein all the concerning formlae have been derived direct, and the fundamental concept is thus clarified.更多还原