Re: [Phys-l] momentum

[Bernard Cleyet <bernardcleyet@redshift.com>]

Another nit --  if it's a brick wall (usually included in the 
premises),  the brick is friable and will contribute to the dissipation 
reducing that of the automobile, in which case I'd prefer the wall. 

bc, who wonders on the relation ship of "The Times-Picayune" and the 
adjective.

p.s. how massive is the wall and how well attached to the "earth"?

Brian Whatcott wrote:

> At 07:38 AM 1/5/2007, A Lapinski,  you 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.
> >    
>
> In the asymmetrical case, some impulse is passed to the Wall/Earth
>  system.   In the symmetrical crash, The Earth does not carry the impulse.
>
> This is however, a nitpick of the picayune kind.
>
>
>
> Brian Whatcott    Altus OK    Eureka! 
>
>
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