Increasing speed makes the laws of physics more and more important to the driver. These laws, although not enforced by a police officer or written by a law-making body, are absolutely binding on all drivers and no one can relax their effect. The laws of physics control each and every object that moves. The particular laws that apply to driving cover areas such as friction, centrifugal force and inertia, impact, and gravity. You should always remember that these laws apply to both city driving and highway driving, because their importance increases proportionally with the speed at which you travel. However, this article on highway driving seems like the best place to discuss its importance.
Proper vision requires enough light and time for an image to impose itself on the retina of the eye, be transmitted to the brain, and thus trigger a reaction from the driver. This means that road signs, signals, and pavement markings become increasingly important when driving at higher speeds. These give the driver advance warning of curves, hills, intersections, or railroad crossings that may be ahead, as well as anticipated maneuvers by other drivers. A driver must learn to recognize all signals and signals instantly, as at higher speeds, the recognition and reaction time becomes shorter and shorter. For easy recognition, signs and signals throughout the United States are standardized by shape and color and can reflect light for viewing at night. Remember, it takes time to observe a sign, signal, or condition and then react to it. The reaction time of a given driver is fairly constant, but the distance traveled in this time is directly related to speed. Therefore, stopping distances and the distances required for evasive action increase as speed increases.
Friction
Friction is the force that opposes the movement of one surface over another, and it is the medium through which a vehicle can move in a straight line, or it can turn or stop. This force is exerted entirely through four small areas of friction, also known as tires. Assuming the mean reaction time is 0.75 seconds, common sense tells us that the faster the car travels, the greater the distance it will take to stop. The difference in stopping distance from 40 miles per hour to 70 miles per hour is about 3.5 times greater. This means that if you can stop within 100 feet at 40 miles per hour, you will need 350 feet of margin to stop traveling at 70 miles per hour.
However, these conditions only occur part of the time: if the friction force is reduced due to ice, snow, rain, oil, mud, loose gravel, a rough surface, or poor tires, the distances of Braking will increase dramatically and evasive maneuvers will increase dramatically. they become much more difficult, or even impossible. Because stopping distance increases faster than speed, it is important to allow more distance between your car and the car ahead as your speed increases.
Inertia and centrifugal force
If at any time the force of friction, or traction, is lost between the four small areas of the tire and the road surface, control is also lost, and one or both of the following physical forces can determine the situation: Inertia , the tendency of a moving body to keep moving in a straight line unless an external force acts to change its direction of motion; and centrifugal force, the tendency of a moving body to rotate around a center to move away from that center. Centrifugal force can be demonstrated by placing a weight on the end of a string and swinging it in a circular motion. If the rope becomes loose or breaks, the weight will leave the circular path and continue in a straight line.
Obviously, a similar effect can happen to a turning vehicle. A car driving around a curve must overcome centrifugal force in order to turn. If the centrifugal force is greater than the friction between the tires and the road, the car will not be able to turn, but it will roll off the road. The key point is that friction increases with speed, but centrifugal force increases even faster. Therefore, the faster your speed or the sharper the turn, the greater the chance that you will not be able to move safely. If you remember this principle, you will find that you must slow down before entering a curve, especially if the road is a bit slippery.
Brakes should never be applied after entering a curve, as this tends to reduce friction between the wheels and the road. Remember, friction allows you to move your car, control it, and stop it. When you consider that for each tire the area that touches the road surface is roughly equal to the size of your hand, it is understandable that many factors can cause friction loss and consequent loss of control. The higher the speed, the greater the possibility of this happening and the greater the consequences. Speed should always be adjusted to suit road conditions.
In addition to the speed of the car, another factor that determines whether or not you will be able to turn safely is the angle at which the road leans around the curve. The easiest is a steep turn (similar to a race track); the second, a flat road; and the third, a crowned surface. The flat surface of the road is dangerous at high speed and in comparison, in a turn, the crowned surface can only be navigated at low speeds because the car is leaning against the direction of the curve. When entering tight curves, there is usually a speed warning sign that tells you how fast you can safely turn the curve. Anyone who ignores these signs is in fact a very dumb driver.
Kinetic energy and impact force
If control of a car is lost, the usual result is a collision, either with another car or with a fixed object. The most important variable in this situation is the force of the impact. The force of the impact itself is a function of the speed and weight of the car. If you double the speed of a car before a collision, the force of the impact is four times greater. If you triple the speed of the car before the collision, the force of the impact is multiplied nine times! Weight also plays a role here; if the weight of the vehicle doubles, the force of the impact also doubles. The total result of doubling the speed and weight of the vehicle would be to increase the impact force eight times. Therefore, any collision would necessarily be eight times more damaging. In effect, the impact of hitting a solid object at 30 miles per hour is like driving from a three-story building.
Highway engineers use various techniques to reduce the force of impact in cases of unavoidable contact with surrounding objects. Smooth metal railings allow a car to bounce instead of hitting hard. Wide road shoulders, free of obstacles such as trees, culverts, and bridge abutments, help reduce hazard. When light and signaling standards are essential, these posts are designed to easily tilt or break on contact. The best way to ensure that the force of the impact does not act on your car is to drive at all times in a way that avoids collision with each and every object!
The force of gravity
Gravity, the force that pulls objects down toward the center of the earth, will cause cars to slow down when climbing hills, thus reducing their stopping distances; and accelerate down hills, thereby increasing your stopping distances.
A good driver will slow down when descending a hill; On steep slopes, you should put your gear selector in low, so that the car’s engine acts as a brake. Hills are potential driving hazards for other reasons as well. They limit visibility; the driver must not pass or approach a hill, no matter how slow the vehicles ahead are moving, unless there is a lane to pass. At the top of a hill, the driver should be alert for oncoming cars that are not in the proper lane, or for obstacles on the road, such as a stopped car while waiting to turn left. Remember that you must be able to stop your vehicle within the distance you can see ahead, whether it is day or night.