Of course, r goes all around the z axis, but I'm just doing a slice through one of these vertical half planes, fixing the value of theta.

当然，r可以围绕z轴转圈，但我只做了一个垂直的半平面，对于一个确定的θ来说。

youdao

1/2I So this can also be written as one-half I, C I put a C there you will see shortly why, because the moment of inertia depends upon which axis of rotation I choose times omega squared.

它也可以被写成，这里我写上,你们马上会发现原因，那就是转动惯量,取决于我选择，哪一个转动轴,乘以ω的平方。

youdao

The Mini-Mill was just big enough for the job - half an inch less travel on the Y-axis would have made the job extremely difficult.

这台迷你机床的大小正好——要是在 Y 方向上再少半寸，那这活可就难干了。

youdao