So I mentioned to you that the motion of the center of mass is very uniform in the absence of external forces, and that I can demonstrate for you again with the air track.
我向你们提到过,重心的运动是稳定的,若不受外力，我可以再次演示,在空气轨上。
So now we're going to turn off the lights and I want to show you the motion of the center of mass.
我们要关上灯，我想给你们展示，质量重心的运动。
Use your hand to power the hoop in a back-and-forth motion: the hoop will alternate between hitting the center of your palm and the back of your hand.
用你的手来给呼啦圈前后移动的力：呼啦圈会在你的手掌心和手背上交替着力。
The motion modeling system structure of virtual gear measuring center is introduced.
介绍了虚拟齿轮测量中心运动建模的体系结构。
The center of ascending motion swings around the equator with variation of seasons.
上升运动的中心随着季节的变化在赤道地区南北移动。
Matching search patterns are designed in the algorithm based on the center-biased characteristics of motion vector distribution.
该算法根据运动矢量的中心分布特性设计了相应的匹配搜索模板。
But some caution is needed in choosing the center of rotation to be employed in evaluating the torques and calculating the motion.
但是，在选择用来求力矩和计算运动的转动中心时，需要注意几个问题。
Centrifugal force: the component of apparent force on a body in curvilinear motion as observed from that body that is directed away from the center of curvature or axis of rotation.
离心力：在曲线运动中可明显由物体上观察到的力的组成部分，这种力使物体具有远离曲线中心或旋转轴心的趋向。
Objective To determine the center of left ventricular(LV) segmental wall motion using color tissue Doppler imaging at various scanning angles.
目的探讨不同扫查角度对彩色组织多普勒显像观察左室壁舒缩运动中心的影响。
Based on the conception of instantaneous motion center, a new virtual vibration system for dynamic balancing measurement is proposed.
根据瞬时运动中心的概念，提出一种全新的动平衡测量虚拟振动系统。
Trace layout module is to convert the profiles of accessories into the motion routes of the tools center.
轨迹规划功能是将加工代码所描述的零件轮廓形状转换成刀具中心的运动轨迹。
The output of sensitivity experiment of moist show that moist could exercise a great influence on typhoon center intensity, typhoon motion and precipitation.
水汽的敏感性试验结果表明，水汽的输送对台风的中心强度、台风的移动路径及台风降水有明显的影响。
The further are using the NCEP/NCAR Global Reanalysis Data and taking the moves TC as the center, then select some grid of the region about the motion TC as the physical quantity predictors (NWP).
进一步根据NCEP/NCAR全球再分析逐日高度场的格点资料，以热带气旋为中心，取移动区域上的格点场资料作为热带气旋路径预报的物理量初选因子。
A direct interpolation algorithm of spiral bevel gear NC machining is proposed, thus establishing the relationship between the motion of the cutter-head center and the rotation of the work gear.
提出了弧齿锥齿轮数控加工的直接插补算法，确定了铣齿刀盘中心运动和工件齿轮旋转运动之间的关系。
The results shown that, with the effect of nonlinear components, the symmetry of rotation trajectory of the bearing center was broken, and the motion of the journal center presented a steady state.
计算结果表明，在非线性因素作用下，轴承中心的轴心轨迹不再具有对称性，而轴颈中心却表现为一种稳定的运动状态。
Based on the image sequence's spatial characteristics of center-biased motion vectors, this method can significantly reduces the search times to (25-55).
该算法由于利用了序列图象运动矢量的空间分布特性—中心偏置分布特性，可以明显地将搜索次数降低到(25 - 55)次。
At present, there is no efficient way to retrace the eccentric error motion of the center from the separated revolved error motion.
从分离出的回转误差运动中有效地提取截面最小二乘圆心的偏心误差运动，目前还没有合适的方法。
The component of apparent force on a body in curvilinear motion , as observed from that body, that is directed away from the center of curvature or axis of rotation.
在曲线运动中可明显由物体上观察到的力的组成部分，这种力使物体具有远离曲线中心或旋转轴心的方向。
A center of rotation that was posterior to the 95% confidence interval for normal motion was 100% sensitive and specific for damage to the anterior structures of the spine.
旋转中心如果在正常活动度的95%的可信区间之后，对棘突前侧结构的损伤则具有100%的灵敏度和特异性。
The gas motion in a cylindrical swirl chamber is analysed and an expression with a spiral locus of air flow toward the chamber center is derived.
本文对圆柱形涡流室内气体流动进行了分析，导出了在室内气体流动轨迹呈螺线状进入室中心时的表达式。
The motion pattern of a scanning point is studied in case a fixed laser beam is pointing at a rotating ball with fixed center.
研究了当用固定不动的激光束扫描球心固定的旋转球体时扫描点在球面上的移动模式。
The result showed that the swing leg has great influence on the motion of the body's center of gravity in the take off.
同时证明，在起跳过程中摆动腿的摆动动作对身体重心的运动状况具有重要的影响。
In this algorithm, nodes are divided into clusters according to their group mobility. Location is updated by prediction of each node with the aid of the motion of their cluster center.
在该算法下，网络节点按照群组移动性进行分簇，在位置更新中利用簇中心的移动来预测各个节点的位置。
A integrated equation set for solving plane parallel motion of rigid body was derived, and the conditions of system of forces simplified on the center of mass plane was discussed.
给出了解决刚体平面平行运动问题的一组完整方程，讨论了力系简化在质心平面内的条件。
According to theorem of motion of centre of mass and theorem of moment of momentum about centre of mass, we derive the theorem of moment of momentum about instantaneous center of rotation.
从质心运动定理和相对质心的动量矩定理出发，导出了相对瞬心的动量矩定理。
Measure the motion energy of the blocks with the energy function and locate the position of typhoon center.
使用能量函数度量各序列块的运动能量，能量最小的块所对应的位置即为台风中心。
In the role of the waves, the son buoys move along the center axis around the mother buoy, and there is no motion between the mother buoy and the son ones. And their relative position is fixed.
在海浪作用过程中，子浮标绕母浮标中心轴上下运动，子母浮标之间不存在周向运动，它们的相对位置是固定的。
In the role of the waves, the son buoys move along the center axis around the mother buoy, and there is no motion between the mother buoy and the son ones. And their relative position is fixed.
在海浪作用过程中，子浮标绕母浮标中心轴上下运动，子母浮标之间不存在周向运动，它们的相对位置是固定的。
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