Re: [Phys-l] Rocket Hovering and Conservation of Momentum

[John Denker <jsd@av8n.com>]

Quist, Oren wrote:

> It depends upon your reference frame !

No, it doesn't.  All accurate observers agree that momentum is conserved.
Always.  Really and truly.  This is true for special relativity as well
as Galilean relativity.

> An external force will change the momentum -- N2!

OK, so what?  Change is not the same as non-conservation.
I'll see your N2 and raise you an N3.

Momentum is conserved -- N3!

> I don't think it is a matter of "constancy" or "conservation".  I think
> it is a matter of being careful to choose your reference frame.

Please show us a reference frame in which N3 is violated, i.e.
in which momentum is not conserved.