Key Inertia

[Mark Davidson]

> >>  So what quantity do we have that is mass times velocity.... but is
> clearly differentiates between each equal product...
>
> Well, mass times velocity is *momentum.*
>
> >> Clearly... 2 x 2 does not equal 4 x 1..... at least in the case of  how
> much mass at what speed hits any given other mass.
> >> What quantity am I looking for here ?
>
> I'm not sure what you mean here.  Kinetic energy, (mv^2)/2, perhaps
> differentiates, sort of, I guess, if I understand you correctly.  Only you'd
> be looking at 2 x 2^2 / 2 being different from 4 * 1^2 / 2, etc.  Is that
> what you mean?
>

>RicB wrote:
>
>What I am saying is that a 10 pound ball going at 5 m/s is going to have a
>completly different affect then a 5 pound ball going at 10 m/s tho both have a
>momentum of 50 momentum units.

I see what you're saying, and the only thing I come up with is the kinetic energies are different (unless V=sqrt(2)).

(Another) Example
When M=1, V=4, M*V=4 but energy = 8
When M=2, V=2, M*V=4 but energy = 4

So I guess to capture this you really have to use momentum AND energy, or mass AND velocity.  You're right, momentum by itself
doesn't capture this.

(You didn't really mix pounds with m/s up there did you? That's almost as
bad as my 1.75"/10mm blow/dip ratio! :) )

-Mark