In table tennis, the surface roughness of the rubber is a key factor, which is closely related to friction and profoundly affects the rotation effect when hitting the ball.
First, the surface roughness directly determines the friction between the rubber and the ping-pong ball. When the surface of the rubber is rough, its microstructure shows more bumps and depressions. At the moment of hitting the ball, the ping-pong ball contacts the rubber, and these microscopic unevenness will fit into each other, allowing the rubber to "grab" the ball more powerfully. For example, when observing some rubber with strong friction under a high-power microscope, you can see that its surface is covered with fine particles or textures. This rough surface greatly increases the contact area and friction, providing a basis for creating rotation. In contrast, the friction between the smooth rubber and the ball is smaller, and the ball is easier to slide on the racket surface, making it difficult to generate strong rotation.
Second, friction plays a core role in the process of generating rotation. According to the principles of physics, friction will generate tangential force on objects. When hitting a table tennis ball, the swing direction of the racket is inconsistent with the direction of the ball's movement. Due to the friction between the table tennis racket rubber and the ball, the ball will be subjected to a tangential force at the moment of contact, thereby generating rotation. Table tennis racket rubber with a large surface roughness can generate greater friction, which means that it can give the ball a stronger tangential force, making the ball produce more obvious rotation. For example, when hitting a loop, the table tennis racket rubber with a rough surface can make the ball rotate quickly around its own axis, making the ball draw a clear arc when flying in the air, making it more difficult for the opponent to catch the ball.
Furthermore, different hitting techniques have different requirements for the surface roughness and friction of the table tennis racket rubber. For techniques that mainly rely on spin control, such as slices and loops, the table tennis racket rubber needs to have a higher surface roughness to generate enough friction to create strong spin. For some techniques that pursue speed and quick return, such as fast attack, although a certain amount of rotation is also required, too rough table tennis racket rubber may affect the hitting speed due to excessive friction. At this time, table tennis racket rubber with relatively moderate surface roughness may be selected, which is more conducive to the transmission of force and the rapid ejection of the ball while ensuring a certain rotation.
Finally, the relationship between the surface roughness of table tennis racket rubber and friction is also affected by other factors. For example, the material of the ball, humidity, and the force and angle when hitting the ball will have an effect on the actual friction effect. In a dry environment, the surface roughness of table tennis racket rubber can play a better role and produce stable friction; in a humid environment, moisture may form a thin film on the surface of table tennis racket rubber, reducing the actual effect of surface roughness, reducing friction, and thus affecting the generation of rotation. At the same time, the greater the hitting force, the more the surface roughness of table tennis racket rubber can be fully utilized to produce greater friction and rotation, but if the force is too large and the friction of table tennis racket rubber is not enough to stably control the ball, it may also lead to hitting errors. Therefore, athletes need to consider these factors comprehensively according to the actual situation, choose table tennis racket rubber with appropriate surface roughness, and flexibly use batting techniques to achieve the best batting effect.
