What is the Principle of Car Movement?
1 Answers
For a car to move and travel at a certain speed, an external driving force must be applied along the direction of travel to overcome various resistances encountered during movement. The driving force is obtained by transmitting the engine's torque through the transmission system to the drive wheels. For a stationary car to start moving, it must overcome four types of resistances, as described below: 1. Rolling Resistance: Rolling resistance is primarily caused by the relative deformation between the tires and the ground due to the car's weight. The magnitude of this resistance is directly related to the car's total weight, tire structure and pressure, as well as the condition and grade of the road surface. 2. Air Resistance: Air resistance arises from the friction between the car's surface and the air during movement, as well as the pressure of the oncoming airflow at the front of the car and the vacuum created by the air vortex at the rear. The magnitude of this resistance is influenced by the car's frontal projected area, aerodynamic shape, and speed, with speed having the greatest impact. 3. Uphill Resistance: Uphill resistance depends on the car's total weight and the steepness of the slope. The greater the car's total weight and the steeper the road, the higher the uphill resistance, and vice versa. Conversely, downhill slopes can become a driving force for the car. 4. Inertial Resistance: Inertial resistance only occurs during the car's variable-speed motion. According to the principle of inertia, when the car accelerates, the inertial resistance acts opposite to the direction of travel. When the car decelerates, the stored kinetic energy attempts to maintain the original speed, causing the car to coast forward.
