The Danger of Driving Over the Speed Limit

Slight increases in speed in vehicles greatly increases the kinetic energy

The Danger of Driving Over the Speed Limit

　

     I recall from my physics class the professor announcing, “today’s lecture is about kinetic energy. Some of you may already know that kinetic energy is equal to the mass of an object, multiplied by the velocity squared and then divided by two. Remember this relationship, double the speed and increase the kinetic energy fourfold. An application of this law for those of you who drive a vehicle is double your speed and take four times the distance to stop.”

     Kinetic energy(K.E.) is also defined by the Wikipedia encyclopedia as the extra energy of an object which it possesses due to its motion. This subject of kinetic energy is also related to the amount of extra energy that is contained in a motor vehicle that is traveling faster than the legal speed limit for a specific road. Because the value for the velocity is squared(multiplied by itself) in the formula for K.E., small changes in speed will lead to large changes in energy in the vehicle, and consequently large changes in stopping distance.

     If a vehicle was to increase its speed from 35 mph, the posted speed limit, to 45 mph, the speed would increase by 29% and the kinetic energy would increase by 65%. If the vehicle speed was to increase from 35 mph to 50 mph then the speed would increase by 43% and the K.E. would increase by 104%. Late for work? Drive 65 mph on Golf Links Road instead of the legal speed limit of 45 mph and increase your speed by 44% and your kinetic energy by 109%, and also increase your stopping distance by 134 feet, for a total stopping distance of 288 feet, nearly the length of a football field.

     The public should be informed about the increased danger of driving over the legal speed limit, based on the formula for kinetic energy. Of course that extra energy is carried not only by the vehicle but also by the driver and passengers, and that extra energy will be quickly dissipated in a sudden, violent stop, which will be translated into trauma of various types, sometimes with fatal consequences.

     We feel secure and comfortable getting into our vehicles and driving at speeds that may suit us, while all the time, lingering and hiding in the background are the laws of physics, always ready in an instant to rear up and show themselves; only upon a sudden stop does the reality of speed appear. Slow down, enjoy the ride, be safe.

Submitted by:

　

James A. Maxey