How stuff works--2

[ws23rt]

I was recalling an earlier thread about a crash test where a charger was run into a hard wall to check on how it crushes.

Lets say the charger was going 60mph.

Another test is two chargers each going 60mph and hit head on.  (Sorry for using chargers they could be chevys)

Would the damage be about the same?  Or would it be more like a 120mph into the wall?

This is an old question but good for those that haven't though about it before.

[Mike DC]

  
Hitting a brick wall at 60mph would probably not hurt as much as going head-on with another car at a combined total of 120mph.  

Both impacts are really gonna suck though.

[XH29N0G]

Thanks again.  "How stuff works" makes me think of a book by David Macaulay with all sorts of diagrams and elephants.  We bought it for my son what seems like ages ago. 

I'll leave this one alone because I have seen it before.  It also was not what I thought  until I learned the answer....

[ws23rt]

Thanks again.  "How stuff works" makes me think of a book by David Macaulay with all sorts of diagrams and elephants.  We bought it for my son what seems like ages ago. 

I'll leave this one alone because I have seen it before.  It also was not what I thought  until I learned the answer....

I may have seen that book some time ago. It rings a bell. I'm sure there are many other books about the nature of things. 
What I have gained from this kind of thinking is to pause a bit when coming to a conclusion about something.
The answers make sense when we see them and why but the lessons are that what our instinct tells us at first is not always the way things are.

[polywideblock]

each car would look like it had been in a 60 mph collision but the amount of energy expelled would be the same as two cars crashing into the wall  if that makes sense  .if a car was ran into a wall at 120 mph the damage would be way worse than the two cars head on at 60 mph or the car into the wall at 60 mph

[ws23rt]

each car would look like it had been in a 60 mph collision but the amount of energy expelled would be the same as two cars crashing into the wall  if that makes sense  .if a car was ran into a wall at 120 mph the damage would be way worse than the two cars head on at 60 mph or the car into the wall at 60 mph

  As two cars meet at 60 mph each they cancel out each others energy.
As one car meets the wall the wall cancels the cars energy just as the second car did.
The wall actually felt (and reacted) to the same impact that the second car did in the head on crash.  We did not see or otherwise feel the walls impact but the wall felt it.

[Green71R/T]

Mythbusters did the test.same as hitting a wall at 60 because both cars absorb energy

[Mopar440+6]

"How stuff works" makes me think of a book by David Macaulay with all sorts of diagrams and elephants.  We bought it for my son what seems like ages ago. 

My parents bought me that book sometime around my 6th or 7th birthday. I still have that book and credit it for the fact that I am now a mechanical engineer.

[ws23rt]

"How stuff works" makes me think of a book by David Macaulay with all sorts of diagrams and elephants.  We bought it for my son what seems like ages ago. 

My parents bought me that book sometime around my 6th or 7th birthday. I still have that book and credit it for the fact that I am now a mechanical engineer.

  Glad to hear that---Many kids these days would be helped much with a few simple explanations of how stuff works. Enough to push them over the tipping point that would give them the confidence needed to find there own answers.

[flyinlow]

My estimate is that the two car collision would be slightly less than the brick wall.  Some of the energy would be turned into rotational energy, the cars not being perfectly balanced longitudanaly.  From the drivers point if you hit a brick wall what happens to the steering shaft is very important. As soon as the steering box and steering shaft impact the brick wall their forward motion will stop. The drivers body will then impact the  steering wheel.
With two Chargers head to head the steering box and steering shaft could penetrate into the other car somewhat reducing the deceleration rate and impact loads on the drivers body.
Might help some compaired to the brick wall.  

[ws23rt]

My estimate is that the two car collision would be slightly less than the brick was.  Some of the energy would be turned into rotational energy, the cars not being perfectly balanced longitudanaly.  From the drivers point if you hit a brick wall what happens to the steering shaft is very important. As soon as the steering box and steering shaft impact the brick wall their forward motion will stop. The drivers body will then impact the  steering wheel.
With two Chargers head to head the steering box and steering shaft could penetrate into the other car somewhat reducing the deceleration rate and impact loads on the drivers body.
Might help some compaired to the brick wall. 

I agree---the example is to show the principal of energy and momentum.  If the wall was a car at rest for example it would move backward from the impact and less damage to both would be the result. Since the wall does not move it acts like a 60mph car.  If the on coming car had a front end that was flat and hard like the wall but the mass of the car the result would be like hitting the wall.

[mrsskip68]

Lets just feel proud & safer that vintage Mopars have "real metal"! Compared to those weenie cars! Always update the seatbelts though! !!!!!

[b5blue]

 I tested this concept endlessly when I was young, with slot cars, hot wheels and anything I could get to crash. My parents even got me a toy car set designed for crashing where the cars had parts that would pop off on impact.
Much later in life I even sat quietly in a Drivers Safety Class while an old fart rambled on after being told: "If a car is coming head on at you your better off avoiding the head on collision even if you hit some other stationary object."  His point was if he did that "It would be HIS liability" and the head on driver would get away from him with no liability.
The resulting impact is NOT canceled out in ether case it is absorbed/distributed into the mass of the objects. The energy in the momentum is double in the head on example. That is how a "Super Collided" experiment is done, two particles are accelerated to "near the speed of light" in opposing directions then crashed together to achieve "higher energy" that effects quantum bonds.         

[Mike DC]

                                           
Are we talking about a hypothetical 100% inflexible, immovable surface for the car to hit?  Or a real world surface/object like a masonry wall? 

I was assuming it was some kind of real world wall.  That affects the answer. 

The kinds of solid objects that a car is likely to hit in the real world can be much tougher than another car.  But they aren't likely to pass back close to 100% of the impact energy inflicted on them.  Pretty much anything besides a giant hunk of diamond embedded into the continental bedrock would soak up a measurable amount of the impact energy.  Whereas the two cars should really be more like an "equal" hit.  So IMHO the two cars going head-on should be a slightly worse impact in most cases. 

[ws23rt]

I tested this concept endlessly when I was young, with slot cars, hot wheels and anything I could get to crash. My parents even got me a toy car set designed for crashing where the cars had parts that would pop off on impact.
Much later in life I even sat quietly in a Drivers Safety Class while an old fart rambled on after being told: "If a car is coming head on at you your better off avoiding the head on collision even if you hit some other stationary object."  His point was if he did that "It would be HIS liability" and the head on driver would get away from him with no liability.
The resulting impact is NOT canceled out in ether case it is absorbed/distributed into the mass of the objects. The energy in the momentum is double in the head on example. That is how a "Super Collided" experiment is done, two particles are accelerated to "near the speed of light" in opposing directions then crashed together to achieve "higher energy" that effects quantum bonds.         

The ---momentum--- of the cars is canceled in either case.   The momentum of the car has a force that is canceled by the immovable object which in effect mirrors the force of the moving car.

If the second car were only going 30mph the 60mph car would cancel it's momentum and lose about 1/2 of it's own. pushing the second car backward at about 30mph.

I'm not up to speed (so to speak) On a cyclotron vs a linear accelerator but my  worth of understanding is that when two particals are accelerated in opposing directions that is like the head on collision in the car crash example.

But in a linear accelerator the fixed target is not like an immovable object (which is an impossible thing)  That would be like a 60 mph car hitting a parked car---Less damage to both cars.

[b5blue]

Here:  http://dev.physicslab.org/Document.aspx?doctype=3&filename=Momentum_Momentum.xml
  This may help clarify your point some...that the "momentum" is reduced to zero. My point was highlighting that in the head on that energy level dispersed is at least double resulting in greater destruction. 
  Fun topic..thanks for posting!
 
  If you really want a head ache, assuming your brick wall is on Earth, its rotating at 1,070 MPH as the world turns and also moving 660,000 MPH orbiting the sun!
So if the car was moving with the Earth's rotation....rounding the Earth on the outer edge of the Earth's orbit....that would mean the cars true speed is 661,130 MPH just before hitting the wall at 60 MPH. 

[XH29N0G]

This will help .  http://www.purdue.edu/impactearth/   

[ws23rt]

Here:  http://dev.physicslab.org/Document.aspx?doctype=3&filename=Momentum_Momentum.xml
 This may help clarify your point some...that the "momentum" is reduced to zero. My point was highlighting that in the head on that energy level dispersed is at least double resulting in greater destruction.  
 Fun topic..thanks for posting!
 
 If you really want a head ache, assuming your brick wall is on Earth, its rotating at 1,070 MPH as the world turns and also moving 660,000 MPH orbiting the sun!
So if the car was moving with the Earth's rotation....rounding the Earth on the outer edge of the Earth's orbit....that would mean the cars true speed is 661,130 MPH just before hitting the wall at 60 MPH.  

It's all relative  ---I do like this kind of thing and may post some more.  The only thing I fear is that someone might spoil the fun by nit picking the terms and meaning of words. That is why I shy away from the "trick " questions.
So far so good 

[ws23rt]

This will help .  http://www.purdue.edu/impactearth/   

Now that is great     I see possibilities of a video game here

[hatersaurusrex]

I will throw this in - a car hitting a wall (or another car) at 120 mph is drastically more damaged than one hitting at just 60, not just doubled - like, completely disintegrated.  Kinetic energy is calculated using the square of the velocity, so every 10 MPH makes a huge difference.