Eric Clapton's
Tears in Heaven was written in memory of his young son who
died in an accidental fall from a multistory hotel window. In a
tragic instant, his son climbed out the window with the speed
and quietness so characteristic of inquisitive toddlers. Genuine
and heartfelt sympathy came from parents all over the world, and
I suspect many readers sadly remember the incident. A parent's
worst fear is losing a child.
For obvious reasons, I've not met a parent who would be
willing to jump out of a seventh-story window or allow his or
her children to play on the outside ledge of such a window. We
would question the judgment, if not the sanity, of anyone
capable of such an act. Yet forty percent of Colorado's parents
expose themselves and their children to a surprisingly similar
risk every day--they fail to use seat belts when riding in an
automobile.
If you are a die-hard (no pun intended) anti-seat belt
person I support your freedom of choice (although you should
make yourself aware of the seat belt laws). But with freedom
comes the responsibility to make informed, intelligent choices.
Read on with an open mind. If you are a casual user of seat
belts, perhaps you will be motivated to make seat belt use a
consistent habit. If you are a full-time user, you might
appreciate some scientific affirmation of your choice.
The Statistics
A single story often makes more of an impression on us than
a statistical number (hence the beginning of this essay). Yet
good, reliable statistics represent thousands of stories,
and show us the common themes among them. Seat belt statistics
are based on studies of thousands of accidents--real
tragedies--from recent years. From the Colorado and US
Departments of Transportation, here they are:
- traffic
crashes are the leading cause of death for Coloradans age 5
to 25
- one out of
three people will be seriously injured in a car crash during
their lives
- nationwide,
two-thirds of auto occupants wear seat belts
- nationwide,
two-thirds of those killed in auto crashes were not
wearing seat belts
- seat belt
users are nearly twice as likely to survive a serious crash
as non-users
The Science of
Seat Belts
Sir Isaac Newton (1642 -1727) was one of the most
influential scientists to have ever lived. His many
accomplishments included proposing the theory of gravity and
developing the three laws of motion. Newton, of course, never
saw an automobile. Yet through his laws of motion he would have
been able to clearly predict and explain the need for seat
belts.
Newton's first law of motion simply states that any moving
object will keep moving at the same speed and direction until
some force causes the object to change its motion. When you
first get in a car, a force is required to change your motion.
As you accelerate the car, you feel the back of the seat pushing
you forward. As soon as you reach a constant speed, though, you
no longer feel the seat pushing you from behind. Your body will
continue to move in the same speed and direction until a force
causes the motion to change.
If a car is traveling at 45 mph and hits a stationary
object, the car will stop but the occupants will continue moving
in the same direction at 45 mph. Unbelted passengers will then
smash into the dash at that speed, or worse, travel through the
windshield until hitting another object (tree, car, pavement).
Belted passengers, though, will be caught by the seat belt,
avoiding a collision with the dash or windshield.
Sobering Comparisons
Colorado ranks below the national average in seat belt
use, with rural areas having the lowest belt use rate. Perhaps
the reason why so many of us don't wear seat belts is because we
just don't think about the forces involved in crashes. Here are
some examples to consider.
Dashboard on a Bumper
Imagine a car with a dashboard mounted on the front bumper
facing away from the car traveling down a road at 45 mph. Would
you be willing to stand in front of it? Of course not, but the
collision is no different than crashing your own car into a
stationary object at 45 mph without a seat belt fastened.
Whether you hit the dash or the dash hits you, the results are
the same.
A Seven-Story Fall
Two seconds after falling out of a seventh-story window a
person would hit the ground at a speed of 45 mph. The bodily
impact would be essentially the same as the 45 mph unbelted
crash mentioned above. None of us would intentionally let our
children out on a high window ledge. Yet, in Colorado, forty
percent of us don't buckle up our kids (or selves).
Throwing Your Arm Out
Many parents mistakenly believe they can restrain an
unbelted child in a sudden stop simply by throwing their arm in
front of the child. Newton's second law explains why this won't
work. Newton discovered that the faster an object moves, the
greater the force required to change its motion. Stopping an
unbelted 50 lb child in a 45 mph crash by throwing an arm in
front of the child would be like trying to stop a 1000 lb steer
from trotting past you at 10 mph with an extended arm. Both
feats require the same amount of energy!
Infant in the Lap
One of the most dangerous places for an infant to ride
in a car is in the lap of an unbelted mother. In a crash, the
infant has little chance for survival. Imagine a 120 lb woman
holding a baby in her lap in a car that crashes into a
stationary object at a mere 30 mph. When the car stops, the baby
and mother keep traveling forward at 30 mph. The baby smashes
into the dashboard at that speed but the worse is yet to come.
At 30 mph, the mother then smashes the baby into the dashboard
from behind with a force of over 1,200 lbs! Even if the mother
is belted in, she will not be strong enough to hold the baby in
her arms. In a 30 mph crash, a twenty pound infant will pull
away with a force of over 200 pounds.
Seat Belt Myths
Most people probably know they should wear seat belts
but many don't think about it enough to form the habit. Still,
some people are convinced they are better off not wearing belts.
Here are some of the myths commonly cited by those who
intentionally don't buckle up:
-It's better to be thrown clear. In fatal crashes, one in
four unbelted occupants are ejected. Of those ejected, three
out of four are killed. An ejected occupant flies head first
through the windshield and into an oncoming car, a tree,
pavement, or some other object.
-Seat belts trap you in a burning car or underwater. Nearly
every crash in the movies or on television involves an exploding
car or a crash in water. The reality is that less than one
percent of all crashes involve either fire or water. In the
unlikely event of such a crash, though, belted occupants are
much more likely to be uninjured and coherent enough to release
themselves.
-Seat belts are only needed on the Interstate. Most crash
deaths occur within 25 miles of home at speeds under 40 mph.
Seat belts should be used on every trip, no matter how short.
-My shoulder harness won't hold me. A built-in convenience
device on newer vehicles allows for freedom of movement under
normal driving conditions but locks the belt in place during any
sudden change of motion. Some people mistakenly believe their
belts don't work properly because of the added freedom of
movement.
-Seat belts cause injuries in a crash. During a serious
crash, seat belts might cause some bruising. However, the
injuries caused by not wearing a seat belt are much
worse.
Make it Click
Car crashes are terrible events that involve incredible
forces. The human body is delicate and fragile. Seat belt use
will not ensure survival of every accident. But it is important
to understand the forces involved in a crash and realize the
effectiveness of seat belts in preventing or reducing injury.
Always buckle up. Sir Isaac Newton certainly would have.
©
2006 Dirk Oden
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