Ultra-Light Land Vehicle Safety: August 23, 2009
Land Vehicle Safety things to think about:more to come...in the mean time go to You Tube and type in Motorcycle Crash and/or type in crash testing for the make and model of the car you drive. Watching these videos is a sobering reminder of the power of inertia and how far we've come in improving vehicle safety.
I hope not to become a bug in the bug/windshield equation, but the physics are not in my favor.
PHYSICS OF MOVING BODIES
The physics behind the collosion are interesting. Let's start with the basics. Newton's laws of motion are three physical laws that form the basis for classical mechanics. They are:
Therefore, when two identical cars (equal mass and equal velocity) run head on into each other, they come to a complete stop where they impact. This is a balanced equation. Both cars experience the same amount of acceleration. Let's say for the sake of argument that both cars were traveling at 35 miles per hour when the crash occured, each car weighed 3,500 lbs and each cars front end crushed in 1 foot during the crash. This means that both cars experienced enough acceleration to decrease their speed from 35mph to 0mph in 1 foot. From this example, and using Newtons laws of motion equations, we can calculate the force and acceleration involved.
With these things in mind, we can also play around with the scenario and exchange one of the vehicles with one that weighs exactly 1/2 of the other vehicle or 1/10th of the other vehicle (as is the case with my BugE and a typical Mini-Van). As it turns out, keeping all things equal except for the mass of the moving object, the acceleration experienced by the lighter vehicle is inversely related to the ratio of the vehicle masses. In lay terms, if your vehicle is 1/10th the weight of the other vehicle your vehicle will recieve 10 times the acceleration as the other vehicle.
CRASHWORTHINESS OF THE HUMAN BODY
There is a threshold for how much acceleration the Human body can recieve without dying (things like your neck breaking and/or your brain bouncing off the inside of your head). The threshold is...more to come...
But don't despair. Just because your vehicle recieves 10 times the acceleration doesn't mean the human inside needs to recieve 10 times the acceleration. Things like crumple zones, air bags, stretchy seat belts, etc. can increase the distance and time the acceleration takes place in, and reduce the acceleration...more to come...
COMMON SCENARIOS OF ACCIDENTS: