|
Sadly,
tragically, and regretfully fans watching a Daytona race a few years
ago lost a great driver, Dale Earnhardt. |
|
If Earnhardt, Sr. had been wearing
the neck brace now required he may have survived the accident. |
|
More importantly, if Earnhardt,
Sr. had understood some basic laws of physics and applied his
understanding to his driving, he would have known not to slow into
the front bumper of the car behind him. |
|
The following paragraphs construct
the last seconds before Earnhardt Sr.'s car was pushed into the
wall. |
The plausible situation
approximately 30 seconds before the fatal crash:
Dale Earnhardt's objective was to block the car behind
him. His successful block would ensure that the driver behind him could not
interfere with Earnhardt Jr. Dale Earnhardt Jr. would be able to take first
place in the Daytona 500 race. |
Nearing the finish line on the last lap approximately 8
seconds before the fatal crash:
1.) Earnhardt, Sr. was driving at high speed;
2.) At high speeds cars float on air. Race cars become light enough to float
because they are buoyed up by wind passing underneath trapped between the ground and the
car. Only the forces of gravity and the downward push of air rushing over front and
rear spoilers and the top surface of the body hold the car down. In summary, the
dynamic net weight of a car decreases as its speed increases. It dynamically
"weighs in" much less at high speed than its curb weight... and it "loses
weight" in direct proportion to its increasing speed;
3.) A car's direction is maintained by momentum and adjusted by steering applied to
the front wheels. Any other force applied to the car will dynamically change its
direction;
4.) The forward drive force and steering forces are applied to the road course
through the tires;
5.) A car is controlled and held stable by the force of friction between a few
square inches of tire in contact with the road. Because the car is relatively
lightened by the updraft, the force of friction between the tires and road is relatively
little and less than the driver --- even Dale Earnhardt --- would experience at slower
speeds. |
|
The situation
approximately 2 seconds before the fatal crash:
1.) Earnhardt eased up on the throttle in order to
intimidate the car behind him. His strategy was to prevent the driver behind him
from passing and possibly winning the race. He thought that if he slowed, the driver
behind him would have to slow down or he would rear-end Earnhardt. This would have
prevented the second driver from over-taking Earnhardt Jr.
2.) When Earnhardt lifted his foot off the throttle to slow and he hoped intimidate
the driver behind him, he over-estimated the second driver's ability and desire to slow
and thus avoid bumping Earnhardt's rear. The car behind him cruised into Earnhardt
and slightly tapped his rear bumper.
3.) The important point is: The car behind Earnhardt was moving forward only a
few mph relative to Earnhardt's car. Their relative speed (the
difference between the two cars) was very small and possibly less than a few mph.
That relative speed differential --- that is, the speed of the car behind him minus Earnhardt's speed --- could impart enough energy to Earnhardt's car to change its
dynamics.
4.) But because the tire-to-road friction was very little (remember
that Earnhardt's car
is nearly floating) the force applied to Earnhardt's car by the tap on his rear bumper did
change Earnhardt's direction. His new direction took him into the wall. He
floated into the wall. Since the tire-to-road friction was so little, Earnhardt's
brakes could not have been very effective even of he had used them. Nor was there
enough distance to stop, let alone even slow significantly, before reaching the wall. |
|
The lesson: Understand the laws of physics and the
application of concepts and interactions before driving through red lights, stop signs,
speeding, cutting in and out in traffic and trying to intimidate other people. |
Relevant laws of
physics &
concepts include:
-- Vector analysis and their additive nature;
-- Friction as a force and the coefficient of friction concept;
-- Aerodynamics;
-- Relative speed versus absolute speed. |
|
Are bumpers for bumping at today's
ultra-high speeds? Definitely not when we understand -- or even
consider -- the coefficient of friction, momentum, and vectors
involved. |
|
And how many amateur Main Street
drivers reading this
story feel really cool while they draft the car in front of them? These
ordinary drivers have no NASCAR experience, no training,
and lack the reflexes to stop quickly. Besides that, they are too
arrogant to even care about stopping quickly. And besides that, they
are so angry at so many things apparently going wrong today that
they actually want to inflict pain on other drivers. |
|
|
|
