Harry wrote: > While the brakes are applied the wheel is not turning about its own centre.
Wrt the ground it isn't, but wrt the distant stars it is, at the rate of one turn per day (it can't be non-rotating wrt both, agreed?). As I said, and as Steven paraphrased and Horace finally opined: "...If it's initially non-rotating wrt the Earth, i.e. rotating once per day wrt the distant stars, it will keep its angular speed i.e. it will remain at rest wrt the Earth." IOW what you drew (wheel not rotating wrt the distant stars) is not what will happen when the brakes are released, on the contrary the wheel will keep rotating wrt the stars at the same rate as before, and therefore will remain immobile wrt the ground, unfortunately (if it had worked as you drew it would have been a nice way to produce energy, by attaching a dynamo to the wheel!). Michel
