Re: momentum transfer

[Richard Tarara <rtarara@SAINTMARYS.EDU>]

----- Original Message -----
From: Doug Craigen <dcc@ESCAPE.CA>
> In a collision with an identical parked car you don't come to rest, you
> come to v/2
Only in an idealized 'physics world' without friction, etc.  If you like,
let the parked car be sitting with it's rear end against an immovable wall.

All of this is nit-picking.  The original statement carries to the general
public the 'correct' idea that a head-on collision between two moving cars
is likely to be more serious than a collision (at the same speed) with a
'fixed' object.  Yes, if the fixed object is really immovable and
uncrushable, and/or the cross-section for the collision is of a different
order, or any of a hundred other details, the equivalence isn't exactly 2 to
1 (can even be nearly 1 to 1), but none of this is essential to the point
being made by the original author.

Rick