Drivers Ed: module 3

Force of impact

Force of impact is the force generated when objects meet. It is a well-known fact that the faster you drive, the greater the impact or striking power of your vehicle. A fact not generally understood is how much greater the striking power of a vehicle is when you double the speed from 20 to 40 mph. It is commonly believed that the striking power of a vehicle would likewise be doubled. This is not true.

Friction

Friction is the resistance of movement between two surfaces in contact. Friction occurs between your tires and the road, in your brakes when applied, and in many parts of your car. If it weren't for friction, you couldn't start, move, turn, or even stop your car in an emergency. You'd have to wait for it to stop itself. The weight of a vehicle produces more friction between the tires and the road surface. For effective friction, the brakes and other parts of your car, including your engine and transmission, should be properly lubricated. Otherwise you may experience mechanical failure.

Inertia

Inertia keeps your vehicle moving until another force slows it down or stops it. This force can be your own action of applying the brake, conditions of the road, an object on the road like fallen tree or—if the driver isn't paying enough attention—another vehicle.

centripetal force

If an object is moving along a curved path, the direction of its velocity is changing. The force responsible for this change in direction is called "centripetal force" which means center-seeking force. It is directed toward the center of the curvature. Centripetal force is necessary for an object to move with circular motion. Centrifugal force is the force that pulls out from the center on a body in circular motion. Centrifugal force is the opposite of centripetal force. Centrifugal force increases with acceleration. Why is centrifugal force sometimes called a "pseudo force"? Centrifugal force is not a real force—rather, it is a reaction to the centripetal force necessary to hold an object at a fixed point in a rotating frame. One of the laws of motion says that "for every action there is an equal and opposite reaction." A force is often referred to as an action. A reaction is sometimes called a "pseudo force." Centrifugal force is actually a reaction to the centripetal force that keeps the object going in a circle. This makes it a pseudo force.

The blue car approaches a curve at 45 mph. The posted speed limit is 35 mph. What should the driver do?

Slow down to the posted speed limit before entering the curve.

potential energy

The definition of the potential energy is "the energy that a piece of matter has because of its position or because of the arrangement of parts." In other words, it is an energy that an object possesses because it has the potential to be converted into other forms of energy. A car parked on an incline may potentially roll down because of gravity. This car has potential energy. Different types of potential energy are controlled by different parts of the car.

The following are rules for safely cornering a curve given the effects of centrifugal and centripetal forces on driving:

The following are rules for safely cornering a curve given the effects of centrifugal and centripetal forces on driving: • Decelerate before the curve • Brake gently and gradually if braking is needed while turning • Downshift if your car has a manual transmission

To keep a parked car from rolling away:

To keep a parked car from rolling away: Leave it in a low gear—or "Park" if it has an automatic transmission Set the parking brake Position the front wheels of your car in such a way that the car will roll away from traffic if your brakes fail The way you will position your wheels will depend on whether you are parked uphill, downhill, or if there is a curb. Turn your front wheels toward the curb if you are parking downhill, and turn them away from the curb if parked uphill. If you are parked uphill and there is no curb, turn your wheels toward the shoulder of the road. It's also a good idea to place an object (like a brick) in front of or behind the tires if parked on an incline.

Traction

Traction is affected in one way or another by friction. For instance, consider the effect of these factors: stopping distance, centrifugal force, and hydroplaning. An increase in any or all of these factors will decrease the amount of traction your car will have because of the corresponding decrease in the opportunity for friction. By decreasing a car's traction, you are decreasing the amount of control you have over the vehicle.

What are the laws and forces that a new driver should know?

What are the laws and forces that a new driver should know? The following sections will cover: • Gravity • Inertia • Momentum • Kinetic and potential energy • Friction • Centrifugal and centripetal forces

Worn or under-inflated tires

Worn or under-inflated tires will reduce the friction between your tires and the road surface, reducing the traction needed to start smoothly, stop quickly, turn, or negotiate a curve in safe manner. The road surface itself may cause excessive wear of tires. When there is too much heat on your tires, the rubber may melt. You may also lose traction if the friction of your brakes is stronger than the friction force between your tires and the road. For effective friction, the brakes and other parts of your car, including your engine and transmission, should be properly lubricated. Otherwise you may experience mechanical failure.

kinetic energy

kinetic energy. This force is the energy developed by an object while in motion. When you double your speed, the kinetic energy of your car is four times as great! And that means the braking distance is four times as great. When you triple or quadruple your speed, the stopping distance is even greater.