Some movements involving primarily vertical or horizontal motions of the body as a whole, in which rotations can be ignored, can be studied using simple equations of linearmotion in three dimensions.
有些运动主要涉及整体的垂直或水平运动，其中转动可以忽略，可以用三维线性运动的简单方程来研究。
2
In this case, I cannot convert linearmotion into the flywheel.
在这个例子中，我不能把直线动能转化到飞轮上。
3
In so far as linearmotion is concerned, a body is in equilibrium if the vector sum of the forces acting upon it is zero.