This has absolutely no tangential velocity.

这绝对没有切向速度。

Because, to get its total velocity, you add the translational velocity to the tangential velocity.

因为要找到它的总速度，我们添加 过渡速度到切向速度。

But we can also describe an object's rotation in terms of its tangential velocity.

我们也可以一半 以切向速度表示物体的旋转。

In fact, its tangential velocity will be equal to its angular velocity, times the radius.

事实上，它的切向速度将是 等于它的角速度乘以半径。

And we know that in general, the magnitude of tangential velocity is also equal to the radius, times the angular velocity.

而我们知道，一般情况下，切向速度的大小也等于半径乘以角速度。

Because at the bottom of the wheel, the tangential velocity is pointing opposite to the direction the wheel is rolling in.

因为在轮子底部，切向速度表示 反转车轮运动的方向。

So, at any given moment, each of those points will have a tangential velocity that depends on the path it moves through -- specifically, the radius of that path.

因此，在任何给定时刻， 这些点中的每一个都会有一个切向速度，该切向速度取决于它移动经过的路径——具体来说， 就是该路径的半径。

But we can also describe an object’s rotation in terms of its tangential velocity. This is the same type of velocity we used when we talked about the physics of uniform circular motion.

但我们也可以根据物体的切向速度来描述物体的旋转。这与我们在讨论匀速圆周运动物理学时使用的速度类型相同。