Re: momentum transfer

[Jim Green <JMGreen@SISNA.COM>]

> The doubling of the speed before hitting the immovable object has several
> nasty effects. The car will need to get rid of four times the kinetic
> energy, and may experience twice the force.
> (if the collision times are equal)

Well, yes, I was wondering how long it would take to realize that, in
assessing collision damage, it is change in total energy that matters
not  the change in total momentum.

But there is another point:  I realize that it is common to ascribe fluid
properties to momentum and say things like "transfer of momentum".  I also
realize that it is difficult to change all this literary momentum, but at
some point we all should say to ourselves -- at least occasionally in a
dark closet -- momentum does not flow -- like energy (and some other
properties) it can be increased or decreased, but not "moved" from one
object to another.  It is like saying the property purple of an object is
transferred from one object to another,

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen