Originally Posted By: paul
your really expressing your inteligence , bryan.

LOL. This coming from the guy who had to crop my post to make it say waht he wanted to - I described an open and closed garbage can.

Cropping the closed garbage can doesn't change that reality.

And don't think your attempt to re-write what I said made us miss the fact that you were completely unable to refute, or even comment on, the difference between the open verses closed garbage can...

What's the matter paul, cannot make your "point" without altering what people have said? Or is this just what you do when faced with a simple, logical answer that completely demolishes your "hypothesis"?

Originally Posted By: paul

but note you need an external force. Whether you're talking about a tank of air, a gun, or guys running up & down ladders, all of those forces are internal

is this how you can have it both ways , bryan.

Nope paul, had you not dishonestly removed part of my post it all would have been consistent. The fact you'd openly try to distort what I wrote - when its all immediately above your post - speaks volumes about your duplicity.

Internal forces in closed systems - i.e. you jumping around in a sealed garbage can - cannot alter momentum of your inertial frame (i.e you + garbage can). To alter the momentum of your inertial frame you need either:

a) an external force, or

b) an open system, so your internal forces can act on the external environment

As I described in my last post...and opposite of how you tried to re-write what I said.

Originally Posted By: paul

is this what happened to newtons laws , add a little here
subtract a little there , reverse a meaning here and there.

Yeah, that's a fair description of what you did. Removed those inconvenient little bits where the laws say things like "external forces".