What Makes Ice so Bad for
Driving?
If you live in a place that
gets hit with generally cold weather, and develops
icy roads, then you know exactly how dangerous
driving on the ice can be. There are a few key
things that you must keep your eye on when driving
in conditions that may have ice build up on the
roads. The first is simply ice, where you can see
it and feel it. The second is something much
scarier and more dangerous, called black ice, that
you cannot see because it is completely
transparent with the pavement below. There are a
few things that change when you are driving on
ice. For the most part, they are obvious, however,
they may not be so obvious until after it is too
late.
All tires
and materials have some sort of coefficient of
friction that occurs between them and the material
they are coming in contact with. According to a
PDF from West Virginia University, the coefficient
of static friction between rubber (car tires) and
asphalt is between 0.5 and 0.9. This is why
generally, cars get very good traction in dry and
ideal conditions. However, driving in conditions
that cause ice build up and black ice to form are
a completely different story. If you are in bad
enough conditions that are close to, or below, 32
degrees Fahrenheit, the coefficient of static
friction of your tires could go down to almost
zero, which would mean that your tires no longer
any traction on the slippery roads. According to a
lecture given by Dick Heckathorn, during
conditions such as the ones described, the
coefficient of static friction between rubber and
ice can be as low as .005, which is a great deal
lower than between rubber and dry asphalt.
Now, you can
add this in to what was talked about earlier in
the chapter, with the force of going around a
turn, and you can see that with an extremely low
coefficient of friction, it would be very easy for
the centrifugal force to overcome to force between
the tires and ice, making ice extremely difficult
to drive on. Ice, because it has such a low
coefficient of friction makes driving much more
dangerous because the force of the contact between
your car tires is significantly reduces from that
of tires and dry road.
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