Re: varying mass systems: rockets included (medium length)

[Cliff Parker <cparker@EMPOWERING.COM>]

Joel Rauber wrote:

> In the rocket in deep space propulsion problem, you deal with a somewhat
> similar situation.  Your system of interest is losing mass rather than
> gaining mass.  We typically utilize conservation of momentum to obtain an
> equation for the motion of rocket that typically appears as follows:
>
> (total mass) a_cm = -U_exhaust* |dm/dt|
>
> In this situation we don't hestitate to call the added terms
> {-U_exhaust* |dm/dt|, in the rocket example} "the thrust " or maybe "the
> force of the thrust".

I believe I followed your statements up to this point.  Please help me to
understand your equation.  Why is the left side including an acceleration
factor?  Shouldn't it be velocity?  On the right side is the -U_exhaust the
velocity of the exhaust as it seems to me it should be?  Perhaps my font makes a
V look like a U.  Perhaps you are indicating something completely different than
what I am thinking.

Cliff Parker