Impacting Physics dialog

All this talk about SUV's supporting terrorism is wrong, the truth is quite the opposite. Actually, if you think about it, if you don't own an American SUV, then you are supporting terrorism. First, if you don't own an SUV, the chance that you will die in a car crash is increased. Everyone knows that increased mass adds to your safety since, if you have a heavier vehicle, then the other car in a collision will not just come to a stop but will actually be pushed backwards. Thus, the vehicle with the lesser of the masses is affected not only by a change of speed from XX mph to 0 mph, but also by some of the opposite force as well. Case in point, all vehicles today are safer than they were ten years ago, but what some people don't realize is that even though you have all that great new life saving technology in your little car, that SUV that you collided with has that same technology but twice your mass as well. Now who do you think will get hurt worse in that crash? More people driving smaller cars means more American deaths, which is one of the goals of terrorists. The second point is that if you don't drive an American vehicle, then you are pushing money out of the US economy and into the economy of whatever country the profits from that purchase went to. This is also known as "leakage" out of our own domestic economy. And unless the same amount of money came into the US economy from someone else, you are just hurting our economy. Thus, you are aiding in one other goal of terrorists. So all you people that say that SUVs are aiding terrorism should reconsider what vehicle you are driving, and think about who is aiding who in this situation.

Brandon Whitelaw

Allow me to point out several errors in your statements. By your logic, heavier cars of the 60s would be safer than cars today, which "everyone knows." In reality, weight has little to due with the survivability of the accident, and those mentioned safety features account for a majority of the reason of the higher survivability rate today. While your logic that when two vehicles collide, the heavier vehicle will decelerate less is correct, it has little to do with safety. In fact, speed it self often has less to do with accident survivability than people perceive. To realize this, all one has to do is watch a modern F-1, CART, or Indy race to see that accidents with unmovable concrete walls happening at well over 100 MPH often result in little to no injury. This is contrary to their sub 1-ton weight. Why? Because they energy from the accident is absorbed by the vehicle rather than the occupant. In a head on collision, the stiff frame rail in trucks (including unit on frame SUVs) often deforms little, transferring the energy from the collision to the occupant, causing extensive injury. In side impact, this same frame rail is so central in the structure, that it is often unaffected in side impact, meaning that all the deformation is happening in the cabin, where the occupants are seated, also a bad situation. Most cars on the other hand are designed to deform a great deal in front and rear impact, so that the energy is absorbed by the vehicle. In side impact, a majority of the vehicles strength is along the sills of the vehicle (what you have to step over to get into the car). These sills will often bend in a side impact accident, absorbing the energy while minimizing intrusion near the passengers central body. In severe accidents this results in leg injuries, but this type of injury is much more survivable than torso injuries. In any vehicle compromises are made, but cars tend to have a inherently better safety design. And I won't even get into crash avoidance, roll-over, etcetera here.

Brendan Miller

There is one concept that I don't think that you understood in my comments earlier. I understand all the logic behind the impact zones in comparison to stiff steel frames. But one concept that you are not addressing is that in an impact between two vehicles the heavier of the two vehicles is going to have less an impact on it thus less impact on the occupants inside it. Where as the smaller, lighter car will suffer much larger amounts of stress to the frame, impact zones, and occupants. An indy car must have those very intense safety zones in order to survive the impact WHILE keeping weight to a absolute minium. As well as the fact that most their crashes are against stationary objects (like walls). It would be virtually impractical to design indy cars like SUV's. Where as it is not so impractical to design small cars to be more like SUV's. Small cars are not restricted to weight because of racing purposes. My simple argument is that with the same technology as a small car (impact zones, air bags, etc...) SUV's benefit from being heavier and larger. If you took a small car and added more weight to the frame as to strengthen the frame on things as side impacts while keeping the impact zones in the front and rear you would have an all around safer vehicle. The only thing holding that back is CAFE standards which restrict fuel millage and thus cause a direct impact of weight reduction on vehicles. Final point being that weight does have a huge impact on vehicle safety when comparing two vehicles with all equal other safety features.

Brandon Whitelaw