Re: [Phys-l] momentum

[John Denker <jsd@av8n.com>]

On 01/05/2007 08:38 AM, Anthony Lapinski wrote:
> I have a collision question (seen in Mazur, p. 131 # 18). A car is moving
> and can crash head-on into a "massive" wall or an identical car traveling
> with the same speed in the opposite direction. If there is no rebounding
> in either case, what should you choose?
>
> Since the final momentum is zero, it should not matter (same Dp). The
> "damage"  will be the same in either case. And since Ft = Dp, the quantity
> Ft must be constant for both collisions. I am also wondering if both the
> impact force AND collision time are the same in each case.

"Same" is the canonical answer.

Slight nit: To correctly obtain this answer, you need to refine
the question, to specify a 1D collision or to specify zero
impact parameter (i.e. head-on collision) ... so that there
is no rotation.  Specifying the "direction" is not quite sufficient
to specify the impact parameter.