它绕着质心的椭园运动就几乎看不出来.Its own elliptic motion around it will be almost imperceptible.在无外力时,质心的速度是常量.The velocity of the center of mass is constant in the absence of external forces.错误的根源在于混淆了质心与重心 吗 ?Do We Mistake Center of ...
最普通的精加工工序是用机械的方法, 如研磨, 磨削或用磨料抛光.The most common finishing operations are mechanical, such as milling, grinding, or polishing with abrasives.实验中采用磨料磨损的方式.Abrasion wearis taken as the main wear mode in the experiments.磨料水射...