Traction is an indispensable factor for the functioning of any vehicle, from a small go-kart to a large freight truck. In the absence of traction, even walking becomes challenging. Although people often use the terms “friction” and “traction” interchangeably, they are not entirely synonymous. Understanding the difference between these two concepts and their essential role in safe driving is crucial.
Losing grip while driving can result in life-threatening skidding, a potentially hazardous situation in larger vehicles. This happens when the tires are unable to grip the road surface, influenced by both the road’s condition and the tires’ quality. It could be fun when driving a go-kart when you control the situation, but quite terrifying and unsafe on a heavier vehicle.
Let’s define friction: it is the force that opposes the relative motion of two surfaces. When driving, the engine produces a force that drives the car or motorcycle ahead. Friction is what doesn’t allow the tires to slide on the surface. There are two types of friction – static and kinetic.
Static occurs when two surfaces are not moving in relation to each other, while kinetic friction occurs when they are. However, on a dry road, even when the wheels are rolling, it’s not about kinetic friction. It’s the static one that makes the car or motorcycle go forward on the course. If we examine the contact part of the tire of a wheel rolling on the road surface under a microscope and in slow motion, we can see that it does not move in relation to the surface. Instead, as the wheel rolls forward, different parts of the tire come into contact with the road.
The importance of friction in vehicle control
We have now figured that it is static friction that ensures the vehicle stays on the right course when driving steadily. But what about other situations?
Friction is a critical factor in controlling a motorcycle, especially during the:
In these situations, maintaining a stronger static frictional force than other forces, such as kinetic energy, is essential to prevent loss of control.
Factors influencing road grip
Road grip is influenced by several factors, including:
- The materials in contact, i.e., tire quality, their texture, roughness, road surface.
- The force pressing the tire and road together, i.e., the vehicle weight.
- Unexpected changes in the surface, such as water, ice, gravel, or oil spills.
In a standard situation, when you go for a ride on a sunny day with the right tires for the season and drive on an evenly paved road, several factors are unchanged, and you have full control of friction. But everything could suddenly alter if it starts to rain heavily or even snow. Drivers must adjust their driving style to changing conditions to maintain control of the vehicle.
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When static transforms into kinetic
When a layer of water, ice, or other materials comes between the tire and the road surface, they act like lubricants. Then the static friction decreases, making the vehicle less controllable. The wheels may spin if too much power is applied when accelerating on ice. They also start to slip when the centrifugal force surpasses the static frictional force. It can result in the motorcycle sliding straight ahead no matter how you turn the steering wheel. At this point, kinetic friction takes over, causing the vehicle to slide.
The wheels will continue to spin till the static frictional force surpasses the kinetic frictional force, which can be achieved by reducing the throttle. At that point, the tires will regain their grip.
Coefficient of friction
The coefficient of friction determines the extent of the slide and the level of slipperiness. Scientists use it to develop new materials for tires and road surfaces. As for the average driver, it’s sufficient to know that high friction is crucial for steady road grip. Understanding the role of friction and its impact on road grip is essential for safe driving.
Friction and traction: understanding the difference
Although often used interchangeably, friction and traction are not exactly the same thing. Friction is a broad physical concept, but when it comes to vehicles, traction specifically refers to the friction between the wheel and the surface of the road. Without traction, a car or a motorcycle can lose road grip and become unstable, making it challenging to control.
After learning about the concept of friction, it becomes clear that traction is determined by the friction between a drive wheel and the road surface. Even the most advanced electronic systems are unable to directly improve traction, but a physical method of introducing a material with a higher coefficient of friction can. This is the same principle applied when sanding an icy road or using snow chains. Ultimately, the physics of the small contact area between the tire and the road surface determines the level of friction and, consequently, the level of traction.
When traction is lost, it is crucial to regain it quickly to avoid losing control of the vehicle. There are various methods available to significantly raise traction depending on the situation, such as using winter tires or adjusting driving style in hazardous conditions.