Given the severe winters of the 2008-2009 and 2009-2010 seasons, many drivers feel some reluctance going into the 2010-2011 winter season. As such, we might consider what is actually happening when we drive our vehicles. In physics, we might successfully model a car as a simple rolling cube, which encounters diverse frictional forces and requires special treatment when one corner encounters a different road surface; however, this model would still be fairly incomplete. As such, we could also model it as a dumbbell shaped object that rotates in order to better describe turning. It is this treatment that helps us understand the hazards associated with driving on slippery roads.
The early 2010 blizzards, which periodically covered much of the United States in significant amounts of snow, should be a reminder of why we must pay attention to how we drive in the winter and what equipment we put on other vehicles. With nearly all the entire lower 48 states covered in snow throughout various periods over the course of a few months and this type of freak weather becoming the norm, learning to drive in similar conditions is a concern for all. Slush and ice are not the only hazards on the road as flooding and excessive gravel on dirt roads also impact our ability to drive. Although “slow down” seems to be the prevailing advice, it is actually not the speed that matters, but rather, the acceleration. As a reminder, acceleration is the increasing or decreasing of speed as well as the changing of direction.
Focusing on the tires of our vehicles, which would ideally be snow tires, cars, trucks, vans, and SUVs can be considered dumbbell shaped object as the two sets of tires are joined together by a “bar,” i.e. the car body. If we want to speedup or slowdown, we push on a pedal to add or subtract rotational force, i.e. torque. With this torque comes another force “pushing” in a direction coming from either in or out of our hubcaps. Where the rotating surface of our tires encounters rolling friction from the road, which causes us to slow, sliding friction helps our tires move in the direction we want them to go; this results from the tire surface being flattened against the road. With the addition or subtraction of torque, as well as changes in direction cause by us turning the wheel or going around a curve, the force pushing in or out from our hubcaps can send our vehicle off course. If the road lacks enough sliding friction to keep us on the road, our dumbbell starts to spin instead of going straight.
In other words, improper acceleration in its various forms is what causes accidents when the roads are slippery. We need to go slow, because it gives us more time to properly accelerate, especially around a curve. On the other hand, going up a hill too slowly in the winter can also throw us off the road since we must add extra torque to our wheels to push the vehicle up the hill and maintain our speed. Consequently, driving on slippery roads requires an effort to consider how fast we are accelerating. For those who live in areas where winter weather is common, a high quality set of snow tires should be a necessity to boost our sliding, as well as rolling, friction. For these individuals and all others, driving safely on a slippery surface means becoming aware of how sudden we accelerate.