In article >,
"Rod Speed" > wrote:

> Alan Baker > wrote in message
> ...
> > Rod Speed > wrote
> >> Alan Baker > wrote
> >>> Bob Ward > wrote
> >>>> Alan Baker > wrote
>
> >>>>> But if you hit a car at anything above a very slow walking
> >>>>> pace, it is going to move some, even with the brakes on.
>
> >>>> some? SOME? How far? Millimeters? Inches? Feet?
> >>>> Yards? You sure like to start tossing out weasel words
> >>>> when the egg hits your face, don't you?
>
> >>> Well, the least it will move is going to be in the case where
> >>> both cars are moving at the same speed after collision.
>
> >> Pity that when the stationary car has the brakes on when hit,
> >> that same speed may well be considerably lower than it would
> >> be if the stationary car did not have the brakes on, stupid.
>
> >> Reams of completely irrelevant desperate wanking with
> >> numbers plucked out of your arse flushed where they belong.
>
> > The speed of the two vehicles after collision is determined
> > by the momentum and the degree of elasticity in the collision.
>
> Duh.
>
> > The minimum that the speed of the stopped vehicle will be
> > is in the case of a completely inelastic collision (where both
> > vehicles move together after the collide) and in the case of
> > equal mass, it will be exactly half the speed of the rear vehicle..
>
> Duh.
>
> Pity what was actually being discussed was the effect of the
> stationary car HAVING THE BRAKES ON AT THE TIME OF
> THE COLLISION ON THE DISTANCE IT MOVES FORWARD
> AND WHETHER THAT CAN AVOID RUNNING INTO THE
> CAR IN FRONT OF THE STATIONARY CAR.

And it *does* move forward. Momentum doesn't just disappear. Having the
brakes on doesn't magically make that speed go away.

If a car on it's own can't stop from 5 mph in zero feet, then if that
same car is struck by another just like it at 10 mph, it will take the
at least the same distance to stop as it would take from 5 mph all on
its lonesome -- more in fact; in the real scenario, it wouldn't
necessarily have the colliding car braking as well.

>
> Presumably you actually are that thick, its hard to believe
> that you can actually be pretending to be that thick.

And since I already did the math, you can see that even at 20 mph,
there's a significant chance of

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."