The Physics Behind Car Crashes

Guinnessy writes "Physics Today has an article on Vehicle Design and the Physics of Traffic Safety. The article analyzes in detail typical crashes experienced between cars, and cars with SUVs'. According to Marc Ross, Deena Patel, and Tom Wenzel, "The evidence is compelling that body-on-frame light trucks cannot safely coexist with passenger cars under existing conditions. That problem is critical because so many light trucks are used nowadays as car substitutes." They suggest some ways in which both cars and SUVs' can be redesigned to improve safety. Meanwhile Detriot News reports on a Pediatrics journal study says that claims that children are no safer in SUVs than cars because of the rollover risks."

Comments

You're both wrong. or right.

[tabrisnet]

KE = (m/2)*v^2

or the more common form: KE = 1/2mv^2

This incidentally does make it in the same class as E=m*c^2 (due to magnitude/exponentiation) but that's more or less irrelevant.

Re:weight& speed are the big issue here

[saider]

From the
National Highway Traffic Safety Administration.

"Do cars with ABS stop more quickly than cars without?
ABS is designed to help the driver maintain control of the vehicle during emergency braking situations, not make the car stop more quickly. ABS may shorten stopping distances on wet or slippery roads and many systems will shorten stopping distances on dry roads. On very soft surfaces, such as loose gravel or unpacked snow, an ABS system may actually lengthen stopping distances. In wet or slippery conditions, you should still make sure you drive carefully, always keep a safe distance behind the vehicle in front of you, and maintain a speed consistent with the road conditions."

ABS is about control, not stopping distances. It allows you to retain control of your vehicle by preventing the wheels from locking up. As such, ABS will not reduce your velocity as much as tradtitional brakes and you will therefore impact with more energy.

However, the benefits of ABS and being able to avoid the collision outweighs the costs of reduced stopping force. So for the untrained driver who simply hits the brakes and waits for impact, ABS can result in higher impact velocities. but used correctly, ABS can help you avoid a collision altogether.

So in some cases (when you cannot maneuver) it is more dangerous, in some cases it is safer.