[Jensson]

> But then following your prior reasoning, that's just another collapse.

But it isn't random, if we know how fast it rotates then the second time we measure it we can get a close to exact result.

The most famous experiment for this is the double slit experiment. Normally when you fire particles through you will get an interference pattern on the other side since the particles passes through like a wave. Measuring it in one will collapse the wavefunction and therefore destroying the inference pattern, so now the particles mostly just travels straight and creates a distribution of hits as if it passed through just a single slit.

Edit: Can look at this picture from wikipedia showing the difference between single and double slit, just measuring at one of the slits will even cause particles passing through the other slit to go much straighter.

https://upload.wikimedia.org/wikipedia/commons/c/c2/Single_s...