The telescope was pointing in the wrong direction.
望远镜对错了方向。
A negative face has an outward normal pointing in a direction opposite that of the positive x-axis.
负向的外法线指向与正x轴相反的方向。
So, what that means is that if I look at my trajectory at this point, that the acceleration vector is pointing in that direction.
这意味着如果我们在这点观察运动的轨迹,它的加速度是指向这个方向的。
"That tail tells you the direction the blood was travelling. So if your tail is pointing that way, which direction was your blood going?"
VOA: special.2010.05.05
This particle is constantly changing its direction, but it therefore has an acceleration and the acceleration, we have shown here, is pointing towards the center.
这个质点恒定地改变它的运动方向,因此它具有加速度,而且这个加速度,我们前面也讲过了,指向圆心
It's good to have a vector pointing in the radial direction of length one.
所以引入这么一个模长为 1,方向沿圆心向外辐射的矢量作用很大
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