Re: momentum transfer

[Richard Tarara <rtarara@SAINTMARYS.EDU>]

----- Original Message -----
From: JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE,
IL 60439

The original statement concerned a head-on collision with _each_ car at v
and a collision with a fixed object also at v.  In my statement below, if
you compare the time to stop for the head-on (each car at v) and a collision
with the parked car but with the a speed of 2v, then I 'think' the stopping
time T will be about the same, giving a near equivalence for these two
collisions.

Rick

> Hi Rick-
>         But I thought the comparison is between two moving cars, each with
> speed V, and a moving car with speed 2V and a parked car.
>                                                 Regards,
>                                                         Jack
> *******************************************************************
> To simplify the discussion (somewhat) let's change the comparison to a
> collision between two moving cars and one moving car and one parked car.
> Now certainly a collision with the parked car at speed v is less serious
> than a head-on with both cars travelling at v.  In Michael's analysis
below,
> the assumption of equal times to come to rest is, I believe, the problem.
> In the head-on, t will be smaller (assuming the center of mass will not
move
> once the cars make contact) than in the collision with the parked car
(even
> if that car doesn't move).
>
> Rick
>
> *******************************************************
>
>
>         "I scored the next great triumph for science myself,
> to wit, how the milk gets into the cow.  Both of us
> had marveled over that mystery a long time.  We had
> followed the cows around for years - that is, in the
> daytime - but had never caught them drinking fluid of
> that color."
>                 Mark Twain, Extract from Eve's
>                 Autobiography