Junkyard: Newsletter Challenge (08/16/05)

What an opportunity to explain all about energy conversion, rates of acceleration/deceleration and why things hurt! And if he gets bored by the automotive examples, there are more to be had from within softball (that's like rounders, yes? But with a ball that's soft?)

And then there's the discussion of the removal of such in car features as big sharp pointy bits in the middle of a steering wheel, and hard point knobs on the dash board. I saw a programme once that said how many thousands of people had survived the impact of the crash only to die from impalement on stylish features such as these.

It's not just passengers who benefit from these things...so do pedestrians. Particularly with the new EU rules on pedestrian protection.

Apparantly, the new EU rules have led to revisions under the bonnet (or hood for our US colleagues) and changes to vehicle leading edge profiles to facilitate 'roll-off' if a pedestrian is struck

This challenge leads us straight into the realms of energy transference and absorption. Sure, the older cars were tanks, but this meant that, in the event of an impact, the force of the impact would'nt be gradually absorbed by the collapse of the vehicle's bodywork. Instead, the kinetic energy would be transferred to objects within the vehicle that were'nt integral to it (namely, the passengers, luggage, etc...) This is the reason that modern vehicles are built with 'crumple zones' that allow the energy transference to take place over a period of time therefore reducing the inertial load on the passengers.

Seatbelts, crumple zones, airbags, head rests to keep the neck from snapping, better & faster trauma care in developed countries all contribute to better survival rates in case of collisions when comparing older cars to the modern ones. There is also continuous research in making the automobile safer. But one flip side of the modern automobile is its low profile to reduce drag. This makes it susceptible to bigger vehicles like SUVs to mount modern passenger car bonnets and crash into the windscreen & passenger compartment during head on collisions. Additionally there is this craze for speed. More the speed, greater the impaired judgement and the impact of collisions and modern cars are fast. So I would end by telling my son, that ultimately it is the human factor which counts. Be alert when driving.

As written in the 8/23 issue of Specs & Techs from GlobalSpec:

Your answer might go something like this: "Well, son, it is true that airbags and seat belts are indispensable safety equipment nowadays. They save thousands of lives around the world. But even without those, cars today are far safer than the cars of yesteryear. You see, yesterday's cars were the 'neutron bombs' of transportation — the equipment was ok after a crash, but the people were hurt or killed." Seeing the vacuous look on your son's face, you move on. "Stay with me here. The older cars were built like tanks, and didn't deform much in a crash. That meant that the decelerations — the negative accelerations the people inside felt due to a crash — were huge, and often not survivable. In today's cars the designers have designed in crumple zones, or crush zones, so that the car crumples up on impact. This crumpling absorbs energy and slows down the deceleration of the occupants. That means lower forces on them, which means that they walk away from wrecks more now than in the past. It all comes down to one of Newton's laws: F = ma." You check to see if he's still paying attention. "If the accelerations are big, then the forces are. That's when bones are broken and internal organs damaged. Slow it all down, buy some time for lower accelerations, and the forces drop as well. In the world of cars, it took awhile for people to realize that it wasn't the car that should survive a crash, but the people inside." Smugly satisfied with the way you answered his question, you then hear, "So can we grab a burger before the game?" Life goes on.