Why I changed my order to a 07 Camry

Windstrings.

Sorry to say it... but you are getting yourself confused. Yes indeed... when two autos hit head on going in opposite directions at 25 mph... there is twice as much energy dissipated than a single car hitting an immovable object at 25mph. However... there are twice as many vehicles absorbing the energy.

The bottom line is that two cars of equal mass, and each going 25 mph hitting each other head on.... is exactly the same as one car hitting an immovable object at 25 mph.

/Jim

 

Ha.. your still pretty funny!.....

Your right there are twice as many vehicles absorbing the energy... there are also twice as many vehicles "releasing" energy too!
So whats your point?

 

Yes, exactly... as long as the wall was truely an immovable object.

/Jim

 

I would guess that's the answer. There are some big cars & trucks out there that rate very poorly.

 

SloopG,

I believe that the Prius has a good design for crumple zones... which is why it has good crash test ratings. It also seems to have a good air bag system.

/Jim

 

windstrings, Jim is right about this. his point is that since there's twice as many cars absorbing twice as much energy, the amount of energy absorbed by one of the cars is the same as if that car had just hit a fixed barrier at 25 mph.

i think one source of confusion is that you can think of the crash from the frame of reference moving 25 mph with one of the cars. in that frame, one car is immobile and the other car is going 50 mph with respect to that frame. people then think that this is equivalent to a 50 mph car hitting a fixed barrier, which is not the case as outlined in my previous post.

 

never saw Newton's experiment on gravity did you...ya know. tossing a big metal ball and a small metal ball off a tower to see which hit the ground first?

*edit*

ok...old news...

 

Personally I like Dave Letterman's version of this experiment. He dropped a six pack of regular beer, and a six pack of light beer... and demstrated that they hit the ground at the same time

/Jim

 

just one quick comment on fixed barriers being anything resembling the same in real life as hitting another car.

when two cars collide, the rate of negative acceleration, though large, is not infinite. when hitting a barrrier, the rate of acceleration is much higher and will cause more damage because of that fact. if you have any doubts about this, ask Dale Earnhart's family

 

Here's a link to a crash test video. Shows the effectiveness of the crumple zone of the engine area:

http://www.safercar.gov/movie/2004/04ToyotaPrius.wmv

Note the airbag deployment and limited motion of the CD (Crash Dummy).

Here's a side impact crash test as well:

http://www.safercar.gov/movie/2004/04ToyotaPrius-s.wmv

 

In a head on crash of two identacal vehicles moving at the sams speed, the kinetic enrgy (KE) dissipated will be 2 x (1/2)mvSQR.

The RATE at which the energy is absorbed is a function of energy absorption design.

The amount of KE absorbed by a vehicle of mass m moving at 50 mph and striking a immovable crash-test barrier will be TWICE that of 2 identical vehicles colliding head-on at 25 mph.

Why? KE is a function of Vsqr. I.e., 25 Sqr = 625. Two vehicles, each at 25 mph will add the same amount of KE; that is (1/2)m x 625 + (1/2)m x 625 = m x 625. If m is 100 slugs (3200 lbs), then total energy is 100 x 625 slug ft Sqr/Sec Sqr.

A single vehicle at 50 mph will have kinetic enrgy of 50 x 2500 slug ft Sqr/sec Sqr.

KE varies as the square of velocity. doubling the velocity quadruples the KE. So 2 identical vehicles at 1/2 the speed will each have 1/4 the kinetic energy compared to moving at the higher speed. But the mass is twice as great (2 vehicles), so the impact at 25 mph each will dissipate 1/2 the KE of a single vehicle at 50 mph.!

 

Seems simple physics to me.... seems you will have to ask someone you respect as knowing more than you "if there is anybody" because I'm not getting through.

One last effort:

Two objects of equal mass traveling the same speed in opposite directions smash into each other... the final effect will be that each object hit with twice the energy being dissipated into "each" object verse simply hitting an object not moving at all.

If one car hit a wall.. the car would be damage and the wall would be damaged... energy transferred into both.... now if the wall or "equal mass" was travelling "towards" the other object, now energy will again be transferred into the object and the object it hit.... except the object it hit is different, it is not moving at speed doubled so the resulting damage is much worse.

If this doesn't make sense to you, thats ok.. I'll even open the possibility that I could be wrong. All math equations seem perfect when you go hand your work to your teacher.. just to find out the whole equation is wrong because one tiny factor was missing.

If you take a pingpong ball and throw it against an immovable wall, it will bounce back a certain distance.
Now if you throw the same ball the same speed against the same wall, but the wall is on the end of someones stick "pingpong paddle", then the ball will go flying across the room, whats the difference?

Maybe you didn't play much baseball and see the different effects on the ball when you "bunt" the ball verses slamming a home run?

This conversation is going nowhere, but its still somewhat amuseing to follow your reasoning.

Gimme another word picture.... I'll play the game!

 

Ok, Denny your over my head with the mathmatics.. but many things make sense to us even though we can't write it down on paper... Try writing love down and explaining that one! :lol:

But what you say makes sense to me and I would not me a bit surprised if things are squared as you speak.

I was a paramedic for 8.5 years in Houston Texas and I see what cars look like that hit walls and what cars "used to" look like that hit head on.... it just totally destroys them as the tremendous energy is transmitted. Cars that flip, fly all over the place are often no-casualtys... but head-ons seem to almost never make it, unless one of the cars was an 18 wheeler or similiar.

 

Windstrings,

I think the problem is that we are talking about an "immovable barrier".... not something that will absorb 1/2 of the energy. When crash tests are performed... they are into such a barrier... hence the car hitting the barrier absorbs all of the energy.

Hence... two identical cars, tavelling in opposite directions at 25 mph... and having a head on collision... is exactly the same as just one of the cars hitting an immovable barrier at 25 mph.

/Jim

 

SloopG,

Additional mass of the Camry would be a huge safety advantage in a collision between two vehicles.

/Jim

 

Apparently many people here are of the belief that stationary objects are immune to the laws of physics. When a car hits a brick wall, equal force is applied to the car and the wall! A 25 mph car and a 0 mph wall results in less energy than a 25 mph car colliding with a -25 mph car. Now, cars will crumple so that does help; a 25 mph car colliding with a 0 mph car will fare best of all.

 

A brick wall is not an immovable object. The crash barrier tests are performed on immovable barriers if I udnerstand it properly... and I am about 100% sure that I do.

The crash barrier test is between a vehicle... and an immovable object with (for all practical purposes) infinite mass... hence the vehicle absorbs the full impact. Therefore... a vehicle hitting the barrier at 25 mph... is exactly the same as two identical vehicles... each travelling at 25 mph in a head on collision.

The crash testing methodology is very misleading because it gives a false sense of security that a low mass car, with good crash rating is safer than a high mass vehicle with a lower crash test rating. In most cases... more mass equals a safer vehicle in a crash.

/Jim

 

To a ping pong ball..a paddle is an immovable mass!....

I'm starting to think your too smart for your own good.

There is a fine line between Genius and idiot!

People like you have difficulty believing fat meat is greasy!

I won't ask you if you believe in God.. but I almost doubt it, because you have difficulty accepting anything that won't fit into the small incasement of your brain.

If you can forget about what you think you know and look at the obvious?

You do believe in the moon don't you? What about wind?... Is love real? Are you sure there are really other planets out there?.. how do you know? have you ever seen them or walked on them?.... maybe those little dots in the sky are just painted on a very high ceiling and everyone has been lying to you?

If you haven't already seen it... you should watch "The Truman Show"... it has Jim Carey in it..... maybe you will like it.... it will test your grasp of reality.