do you know science?

I got this answered in high school physics. The point of the exercise is about Newton's second law: for every action there's an equal and opposite reaction. Whey you try to push down a wall with your bare hands, the reason you can't is because the wall pushes back at exactly the same force. ("How does the wall know how hard to push?") The trick part is that people are supposed to think that you hit the other moving car with the force of an

80 MPH crash, which simply isn't true. The crash plane acts exactly the same as the brick wall.

It's somewhat like the fish scale supported horizontally between two pulleys with weights hanging:

_______________ __________/ fish scale \___________ O \_______________/ O

Have you ever seen what going through a windshield does to a human body?

I once saw some drunk (or maybe a druggie) drift off the road into a tree. The two occupants left two "headprints" on the windshield, and they got out of the car with blood streaming down their faces. I was delivering papers at the time, so didn't want to get involved (my customers' papers would have been late! =:-O ) - the two guys ran, apparently because they didn't want to get in more trouble than they were already in.

And they only _cracked_ the windshield - I wouldn't want to see someone who had gone _through_ one.

Cheers! Rich

You can add with a slide rule? =:-O

Thanks, Rich

Water. Duh!

Thanks, Rich

Your calculator is seven off.

Thankyou.

Sylvia.

Well, that's nice to know, though it's something of a revelation to me that I am expected to conduct myself on Usenet in a way that specifically avoids things that you object to.

Probably including some that you never notice because no one feels the need to comment on them.

Stuff happens. If it upsets you, don't use Usenet.

Sylvia.

altruistic: pretending unselfish regard for or devotion to the welfare of others, while sneakily screwing them over... as in Obamaism. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed

=A0 =A0 ...Jim Thompson

or this ....

altruistic: pretending unselfish regard for or devotion to the welfare of others, while sneakily screwing them over... as in public union workers being motivated by their love of the children.

I would go for hit the cement because there mos definitely be less KE in the impact, BUT.. ..with a modification of veering as much as possible to maximize impact on passenger side (assume NO passenger) and thus minimize impact on driver side. That would tend to convert some of the energy into a spinning mode; the more that way, the better.

The lack of longitudinal symmetry means that in the two car case, a driver might be impaled on something projecting from the opposing vehicle.

At best one might conclude that on balance, the two car case is safer, but I don't think one can say that in every case where a driver would have survived the concrete impact, they would also have survived the two car impact.

Sylvia.

Or filter Sylvia. >:->

Cheers! Rich

I've seen a video clip secreted from a union meeting, where a union leader says exactly that... they're in teaching for their own benefit.

We're in a tenuous point in our history. We're either going to go under... OR... it'll dawn on everyone that, for some important reason, there's a waiting list at every charter school. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed

I like the movie "Altured States".

Unless the cars are very old, or it's really pickup trucks or truck-chassis SUVs, they don't have separate frames, just bodywork. (Back when that was novel, it was called 'monocoque' construction.) So there's nothing much to be impaled on. Still, your best hope of survival is seriously asymmetrical buckling of the engine compartments, so that the crushing happens selectively on the passenger side of both cars. That stands some chance of letting them separate again with a fair chunk of their initial momentum.

Cheers

Phil Hobbs

But if identical, they would cancel. Car makers typically offset the front end weight locations (air conditioner, starter, etc) to make up for this as well, so the car very likely weighs more on the right side empty, and is 'balanced' as it were, with a 165 Lb weight in the driver's seat.

The car also consumes energy while crumpling, giving the driver's muscle response more time.

The car-car impact is likely less damaging to the car(s) as they both act like single use springs during the collision.

The 20' block is motionless, and only ONE car gets crumpled, so at least twice the energy will be reverberating through the chassis as the crumple occurs, and the final, crumpled chassis should be crumpled MORE than the two car collision would yield.

So, in the two car game, the cars get a break from the collision... from each other.

In the 20 foot block, the car collides with a 100% immovable object that is 100% rigid from the contact face inward. That is one car I would not want to be in.

I haven't been 165 pounds since I was 12.

Cheers

Phil Hobbs

Well, there's half, but also half as many cars. I don't think energy considerations help.

There is perhaps a temptation to calculate the energy by reference to the relative velocity, which would give an answer four times as high for the two cars, but that's clearly wrong, since it would provide a mechanism for creating energy.

I agree with letting the passenger side take the impact, but I think the focus on energy is misguided. While it clearly takes energy to damage a driver, what really matters most is the forces, where they're applied, their strength and duration. Having the car spin will result in torsion on the driver. It would be better IMHO, if there were another obstacle so positioned as to prevent the car from turning when the passenger side hits the concrete.

Sylvia.