Is the movement of a wheel a translational phenomenon?
2 Answers
The movement of a wheel involves the overall translation of the vehicle, while the power and transmission parts of the car rotate. This is the principle of a car: converting reciprocating linear motion into rotational motion to achieve linear translation of the vehicle. A wheel is a rotating component located between the tire and the axle that bears the load. It typically consists of two main parts: the rim and the spokes. The functions of an automobile wheel include: 1. Supporting the entire vehicle's weight and transmitting traction, braking force, driving torque, and braking torque; absorbing and mitigating shocks and vibrations caused by uneven road surfaces; improving the adhesion performance between the wheel and the ground. 2. An automobile wheel is composed of the hub, the rim, and the connecting part between these two components. Since the wheel is a rotating body, it requires high dimensional accuracy, low imbalance, and must possess certain elasticity and rigidity, fatigue resistance, lightweight, and good economic performance. 3. Additionally, the wheel's rim is the part that mounts and supports the tire, while the spokes are the supporting components between the axle and the rim. Apart from the aforementioned parts, a wheel sometimes also includes the hub.
I've been fixing cars for over twenty years, dealing with wheels every day. Translation means the entire object moves together without turning or tilting. But wheel motion is different—when a wheel rolls, the part in contact with the ground rotates while the whole car moves forward. So a wheel's movement includes both translation and rotation. The wheel's center point moves almost purely translationally, with the axle moving straight along with the car; but points on the rim trace circular paths, changing position like little nuts. In daily life, you can see the difference when driving: wheels roll when accelerating on flat roads, yet keep rotating without much movement when braking. This is crucial for safety—if wheels lock up and stop rotating, pure skidding occurs, making slipping and accidents more likely, which has nothing to do with pure translation. During repairs, we always check bearings to ensure smooth rotation, balancing motion and driving.
