Watch out Paul, here I come into this thread too! :P

Originally Posted By: paul

so I stay on "think street"

I'm all in favour of thinking too, that's why I like this forum so much.

Just because somebody didn't explain all their reasoning about everything doesn't mean they didn't think it, either right then or way back in the past.

I remember when I was a physics student, a fellow student was spinning on his chair without touching anything else. As we've probably all done, twist your body quickly, then slowly back the other way. You get a net rotation in little fits and starts. He was doing that and said "Hey shouldn't this be impossible?". But then we figured out that the friction is different for different speeds so it does allow angular momentum to not be conserved locally.

The flailing hose example is irellivant because it's obviously losing material, air, that isn't recovered.