Damn, and I just packed up my old college physic books for storage until my
office gets renovation completed! I would have loved to look that one up, I
can not remember most of my physics stuff, too long ago.

MC


"Joseph Meehan" wrote in message
...
Borrall Wonnell wrote:
You *are* bored.

I'm bored so will put forward this one to see what happens:

2 cars of equal mass crash head on at 50 mph. Both drivers will feel
an impact equal to crashing into a solid object at:
a. 100 mph
b. 50 mph
c. Other


Hmmm...is this a trick question? It's been a while....

Look at billard balls. When the cue ball strikes a stationary ball
head-on (ignoring spin), the stationary ball beings moving and the cue
ball stops dead.
Let's say the cue ball was travelling at 50mph. Effectively it has
hit a 'brick wall' at 50mph since it stopped dead.

Not really. The "brick wall" or more correctly an immovable object
does
not absorb any of the energy, it moves not at all. The stationary ball
absorbs all the forward energy (ignoring losses) and uses this energy to
move with. If the cue ball hits an immovable object it must absorb the
energy itself, either bouncing off or flexing or breaking up.

So if the second
ball was travelling in the opposite direction at the same speed, the
cue ball would not just stop, but 'bounce' and travel at 50mph in the
oppposite direction. Effectively hitting a wall at 100mph.

Correct so far? Maybe, maybe not. At this point I don't care.

Now, that's all well and good but cars are a different story.
Collisions are not perfectly elastic due to crumple zones and other
losses. Assuming both cars 'stick' together after the collision, the
wreck will remain stationary at the point of impact. In this case,
each driver will feel the effect of hitting a wall at 50mph (i.e. each
goes from 50mph to 0mph).

If the cars 'bounce' off each other, then the impact will be somewhere
between 50 and 100mph.

Of course, dont forget about seat belts and air bags which may save
their lives....if that gas leak didn't engulf the vehicles in flames
first.

Do you actually have an answer to this 'problem'?

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math