What does the size of adhesion mean in Subject 4?
2 Answers
Subject 4 adhesion refers to the adhesion condition between tires and the road surface. The size of adhesion is the product of vehicle weight and the road surface adhesion coefficient. This applies to the entire vehicle. For a single wheel, the adhesion of that wheel should be: the vertical reaction force from the ground on that wheel multiplied by the road surface adhesion coefficient. Below is the relevant introduction: 1. Definition of Subject 4: Also known as Subject 4 theoretical test or driver theory test, it is part of the motor vehicle driver's license assessment. 2. Content of Subject 4: The test paper consists of 50 questions, mainly in the form of cases, pictures, animations, etc., with a full score of 100 and a passing score of 90.
I remember being a bit confused by the concept of adhesion during my Subject 4 exam. Essentially, it refers to how well the tires grip the road. Simply put, it's about whether the car can stay firmly planted on the ground without slipping. I read in the textbook that with high adhesion, acceleration and braking are more reliable. However, when it rains or there's snow and ice on the road, adhesion decreases, making it harder for the tires to maintain grip, which can lead to skidding or loss of control. During the exam, they emphasized that when adhesion is low, we should drive slower and maintain a longer following distance to prevent accidents. In daily driving, I always remind myself to pay attention to this, especially in rainy conditions where reduced adhesion due to wet roads is common, and speeding up might make it hard to stop in time. After getting new tires, I noticed a significant improvement in adhesion, making driving feel much safer.
