Drive a Porsche? Are you a "target"?
08-02-2005, 10:41 PM
#46
Drifting
Join Date: Apr 2004
Location: Tucson AZ, Dallas Tx sometimes
Posts: 2,966
Likes: 0
Received 1 Like
on
1 Post
This debate is about the decelleration of a moving mass. e=mv^2 the v is velocity m is mass and e is energy.
lets do car A:
1500 kg (metric is easier) car moving 15.6 m/s (35 mph) this is 222 kilojoules
car A has 222 kj of keinetic energy that must be absorbed in to the body structure.
Car B is also a 1500kg car going 35mph that is another 222 kj of energy. so between two cars there is 444 kj of energy to be distributed. If one vehicle was like a tank it would distribte more of its enegy to the other car.
Now lets see if 70 mph is more than 222kj.
Car A is moving 31.3 m/s and is 1500 kg that is about 1,470 kj of energy. over 3 times more energy than a 35 mph crash.
Case solved.
lets do car A:
1500 kg (metric is easier) car moving 15.6 m/s (35 mph) this is 222 kilojoules
car A has 222 kj of keinetic energy that must be absorbed in to the body structure.
Car B is also a 1500kg car going 35mph that is another 222 kj of energy. so between two cars there is 444 kj of energy to be distributed. If one vehicle was like a tank it would distribte more of its enegy to the other car.
Now lets see if 70 mph is more than 222kj.
Car A is moving 31.3 m/s and is 1500 kg that is about 1,470 kj of energy. over 3 times more energy than a 35 mph crash.
Case solved.
08-02-2005, 10:54 PM
#47
Pro
Originally Posted by adrial
Trees and light poles do not absorb enough energy to make a difference, they stand there and give you the finger and ask why you hit them with your 3000lbs car??
08-02-2005, 10:56 PM
#48
Originally Posted by Campeck
that crash was not engineering. there comes a point in an impact where no ammount of metal or stiffness is going to help. any car that goes sideways and hits a pole at over 60mph is going to be destroyed.... he got lucky. if a 944 rearends another vehicle and the other vehicles reaend is now nowhere to be found..but you can still see your hoodcrest. thats engineering. not someone being lucky as hell to walk out of a car that curled itself around a pole.
ah whatever.
ah whatever.
08-02-2005, 10:58 PM
#49
Pro
Join Date: May 2002
Location: Franklin, MA
Posts: 719
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by azmi951
This debate is about the decelleration of a moving mass. e=mv^2 the v is velocity m is mass and e is energy.
lets do car A:
1500 kg (metric is easier) car moving 15.6 m/s (35 mph) this is 222 kilojoules
car A has 222 kj of keinetic energy that must be absorbed in to the body structure.
Car B is also a 1500kg car going 35mph that is another 222 kj of energy. so between two cars there is 444 kj of energy to be distributed. If one vehicle was like a tank it would distribte more of its enegy to the other car.
Now lets see if 70 mph is more than 222kj.
Car A is moving 31.3 m/s and is 1500 kg that is about 1,470 kj of energy. over 3 times more energy than a 35 mph crash.
Case solved.
lets do car A:
1500 kg (metric is easier) car moving 15.6 m/s (35 mph) this is 222 kilojoules
car A has 222 kj of keinetic energy that must be absorbed in to the body structure.
Car B is also a 1500kg car going 35mph that is another 222 kj of energy. so between two cars there is 444 kj of energy to be distributed. If one vehicle was like a tank it would distribte more of its enegy to the other car.
Now lets see if 70 mph is more than 222kj.
Car A is moving 31.3 m/s and is 1500 kg that is about 1,470 kj of energy. over 3 times more energy than a 35 mph crash.
Case solved.
I must have missed this day at school
08-02-2005, 11:46 PM
#50
Nordschleife Master
Originally Posted by MTM
Actually, now that I think about it, trees and poles are probably worse than crashing into another car. The contact area is smaller, so the pressure/stress on the car is larger. For example, even though this tree did absorb a lot of energy when it got pushed over, it probably damaged the car more than a solid concrete wall would have. It's like the difference between stepping on a single nail and lying down on a bed of nails.
08-02-2005, 11:54 PM
#51
Nordschleife Master
Originally Posted by azmi951
This debate is about the decelleration of a moving mass. e=mv^2 the v is velocity m is mass and e is energy.
lets do car A:
1500 kg (metric is easier) car moving 15.6 m/s (35 mph) this is 222 kilojoules
car A has 222 kj of keinetic energy that must be absorbed in to the body structure.
Car B is also a 1500kg car going 35mph that is another 222 kj of energy. so between two cars there is 444 kj of energy to be distributed. If one vehicle was like a tank it would distribte more of its enegy to the other car.
Now lets see if 70 mph is more than 222kj.
Car A is moving 31.3 m/s and is 1500 kg that is about 1,470 kj of energy. over 3 times more energy than a 35 mph crash.
Case solved.
lets do car A:
1500 kg (metric is easier) car moving 15.6 m/s (35 mph) this is 222 kilojoules
car A has 222 kj of keinetic energy that must be absorbed in to the body structure.
Car B is also a 1500kg car going 35mph that is another 222 kj of energy. so between two cars there is 444 kj of energy to be distributed. If one vehicle was like a tank it would distribte more of its enegy to the other car.
Now lets see if 70 mph is more than 222kj.
Car A is moving 31.3 m/s and is 1500 kg that is about 1,470 kj of energy. over 3 times more energy than a 35 mph crash.
Case solved.
For someone that seems so cocky you forgot the 1/2 in front of the mv^2...
But, going with that error ... how do you get 220 KJ? 15.6^2 * 1500 = 365 KJ
08-03-2005, 12:21 AM
#52
Race Car
Join Date: Sep 2003
Location: Orfordville, WI
Posts: 4,202
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by 944Fest (aka Dan P)
Scoot, I think you've got my concept. Not only deformation, but where the energy goes, as in, does the car just plain STOP. If a locomotive going 35 MPH Eastbound with a CONCRETE bumper hit a car going 35 MPH Westbound, and the car ended up changing course 180 degrees and accelerating to 35 MPH in the opposite direction almost instantly, there ya got a 70 MPH collision as the mass of the "colidee" made a 70 MPH change in direction. If two cars nail head on, both 35 MPH and come to a dead stop instantly, there is nothing there other than 2 x 35 MPH impacts to a dead stop. Anyone else have input?