why do ping pong paddles have two different sides
Table tennis racket Table tennis regulations approved by the International Table Tennis Federation (ITTF) allow different surfaces on each side of the paddle for various amounts of spin (including nullifying it) or speed.[1] For example, a player may have a spin-heavy rubber on one side of his paddle, and no spin on the other side. The player can flip the racket in play for different types of returns. To help a player distinguish between different types of rubber used by his opponent, regulations specify that one side of a paddle must be red while the other must be black, allowing a player to see what side of a paddle hits the ball mid-play. The player has the right to inspect his opponent's racquet before a match to see the type and color. Current rules state that, unless damaged in play, the paddle cannot be exchanged for another at any time during a match.[2]
Z-transform The Z-transform can be defined as either a one-sided or two-sided transform.[7]
Pulse Pressure waves generated by the heart in systole move the arterial walls. Forward movement of blood occurs when the boundaries are pliable and compliant. These properties form enough to create a palpable pressure wave.
Alonso Álvarez de Pineda