C5 Golfer Posted March 9, 2005 Report Share Posted March 9, 2005 Here is the problem to think about. Two identical cars traveling at each other at lets say 50 mph collide perfectly down the centerline head on. The damage to each car would theoretically be the same Right? But what if the same car hit an immovable solid brick wall at the same speed? Would the damage to the car be equal to the damage in the head on? Hummmm ( You can tell I am bored and since there is no snow I felt the need for a post):D Quote Link to comment Share on other sites More sharing options...
Jack M Posted March 9, 2005 Report Share Posted March 9, 2005 If you're talking two identical cars, then the dammage would theoretically be just as extensive to each. Otherwise it depends on the construction of each vehicle (crumple zones, ladder frame vs. unibody, etc) But hitting a brick wall or concrete bridge abuttment would be worse because they don't have crumple zones! Quote Link to comment Share on other sites More sharing options...
trailertrash Posted March 9, 2005 Report Share Posted March 9, 2005 I think hitting the oncoming car would be worse as they have more force towards you. Thats why they put dividers in highways. I think Bob J. can model something up for us... john Quote Link to comment Share on other sites More sharing options...
Jack M Posted March 9, 2005 Report Share Posted March 9, 2005 oh yeah, I read that wrong, silly me. The car hitting the wall would have to be travelling 100mph to equal the dammage of a head on collision of 2 cars going 50mph. Although the 2-car accident would be not quite as bad due to crumple zones. Quote Link to comment Share on other sites More sharing options...
skywalker Posted March 9, 2005 Report Share Posted March 9, 2005 Hi Jack, sorry for that, but you're as wrong as one can be. Car No1 will be decellerated from 50 to 0. Car No 2 will be decellerated from 50 to 0. You could put a wall between them and get the same result... or a sheet of paper. This is not at all true for two different cars! Quote Link to comment Share on other sites More sharing options...
Jack M Posted March 9, 2005 Report Share Posted March 9, 2005 Car vs. Car, 50mph: the destruction of the two cars will absorb some of the energy of the impact, cushioning each other and the occupants by some ammount. Edit: this would be equivalent to parking car A without the e-brake, and driving car B into the front of car A at 100mph. I'd rather do that than drive into the wall at 100mph. Quote Link to comment Share on other sites More sharing options...
Hagen Posted March 9, 2005 Report Share Posted March 9, 2005 Jack, I have to agree with skywalker. You would have to add extra energy for the two car crash to cause more damage than when you drive a car against the wall at the same speed. Hagen. Quote Link to comment Share on other sites More sharing options...
skywalker Posted March 9, 2005 Report Share Posted March 9, 2005 Sorry, what does BSME stand for? Pretty sure this would be equivalent to parking car A with its rear bumper against a wall, and driving car B into the front of car A at 100mph.... no? hmmm... You were talking about a wall with zero energy absorbtion. I'd rather say it's like one car with the speed of 100mph hitting another (identical) car without speed and WITHOUT a wall behind. Remember: Sum of the speeds of both cars is 100. You have total absorbtion energy of both (2 times car #1). So in sum 2 times the absorbtion energy of car 1 and in sum two times the speed of car 1... will end up with the impact of car 1 hitting a wall without any energy absorbtion with 50mph. Sure ;) Quote Link to comment Share on other sites More sharing options...
Corey Posted March 9, 2005 Report Share Posted March 9, 2005 BSME = Bachelor of Science in Mechanical Engineering. I've got one too! ;) Providing the cars are identical, either situation would be the same. That's why all the crash tests you see are of a car running into an immoveable object. A 50 mph crash isn't going to be pretty! Most of the crash tests you see where the cars fold up like accordians are at 35-40 mph. Quote Link to comment Share on other sites More sharing options...
D-Sub Posted March 9, 2005 Report Share Posted March 9, 2005 and I get **** for MY posts? sheesh Quote Link to comment Share on other sites More sharing options...
C5 Golfer Posted March 9, 2005 Author Report Share Posted March 9, 2005 Originally posted by skywalker Hi Jack, sorry for that, but you're as wrong as one can be. Car No1 will be decellerated from 50 to 0. Car No 2 will be decellerated from 50 to 0. You could put a wall between them and get the same result... or a sheet of paper. This is not at all true for two different cars! Skywalker -- you go to the head of the class. Good Job! Jack - well better luck next time. Quote Link to comment Share on other sites More sharing options...
skywalker Posted March 9, 2005 Report Share Posted March 9, 2005 Sorry Jack, it was not my intention to make this something personal!! Tom Quote Link to comment Share on other sites More sharing options...
Neil Gendzwill Posted March 9, 2005 Report Share Posted March 9, 2005 IIRC the point where people get confused in these types of problems is where they say "is a head-on collision where both cars are going 50 kph the same as hitting a wall at 100 kph". The answer is that the wall is much worse in that case. Quote Link to comment Share on other sites More sharing options...
CarvCanada Posted March 9, 2005 Report Share Posted March 9, 2005 uh oh now we have the metric system in there as well! :) Quote Link to comment Share on other sites More sharing options...
mirror70 Posted March 10, 2005 Report Share Posted March 10, 2005 Originally posted by Bob Jenney Since we suspect that the wall is going to have more mass for a given cubic inch You can suspect anything you want, but the density of the wall is irrelevant. It is the mass (density * volume) that counts. Quote Link to comment Share on other sites More sharing options...
Jack M Posted March 10, 2005 Report Share Posted March 10, 2005 Originally posted by C5 Golfer Skywalker -- you go to the head of the class. Good Job! Jack - well better luck next time. Jetta vs. Jetta both at 50mph head on does <b>NOT</b> equal Jetta at 100mph vs. huge stationary block of concrete. The latter would cause more dammage to the car. This was what I was originally trying to say. Jetta vs. Jetta both at 50mph <b>DOES</b> equal Jetta at 100mph vs. freestanding Jetta at 0mph, like Skywalker said. Again, this is what I was originally saying - "the 2-car accident would be not quite as bad due to crumple zones." This is why they build crumple zones into cars. Back to <b>the original question</b>: "But what if the same car hit an immovable solid brick wall at the same speed?" This scenario (car at 50mph vs wall) involves half the momentum of two cars at 50mph. HOWEVER, because the wall is infinitely more massive than the car and does not appreciably crumple upon impact, the dammage to the car will be more than half as bad. I'll take my seat at the head of the class now. ;) Now, when you add centrifugal force to the equation... :D Quote Link to comment Share on other sites More sharing options...
mirror70 Posted March 10, 2005 Report Share Posted March 10, 2005 Originally posted by Bob Jenney "...mass for a given cubic inch" is volume. No, that's called density. Density is measured in mass per unit volume. A cubic inch is a measure of volume. You said "mass for a given cubic inch," which is density. Quote Link to comment Share on other sites More sharing options...
Jon Dahl Posted March 10, 2005 Report Share Posted March 10, 2005 I'll inspect them and tell you if they are repairable! Quote Link to comment Share on other sites More sharing options...
trailertrash Posted March 10, 2005 Report Share Posted March 10, 2005 wait, if you have two jettas heading towards each other at 52 mph and they turn their headlights on, does either driver see anything? Quote Link to comment Share on other sites More sharing options...
Phil Posted March 10, 2005 Report Share Posted March 10, 2005 I feel that I need to point something out to all of you about this matter...... There is still snow on the ground! (can't this wait until summer?):D Quote Link to comment Share on other sites More sharing options...
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