Table Tennis: The Science of Spin and Speed

Table tennis, also called ping-pong, is played by over 300 million people worldwide, making it one of the most popular sports on the planet. Two or four players hit a lightweight hollow plastic ball back and forth across a table divided by a low net. The table is exactly 2.74 meters long and 1.525 meters wide — about the size of a large door lying flat. Each rally is incredibly fast: top professional players can exchange the ball over 100 times per minute, reacting in less than a quarter of a second!

The paddle (also called a racket or bat) is where the real science lives. The blade — the flat wooden part — is usually made of five to seven thin layers of wood glued together, sometimes with carbon fiber layers for extra stiffness. On each side of the blade is a sheet of rubber. The rubber has tiny bumps called pips. Most players use inverted rubber, where the pips face inward, creating a smooth outer surface. The rubber traps the ball momentarily and grips it, allowing players to put spin on the ball with a brushing motion.

Spin is the secret weapon of table tennis. When you brush the top of the ball as you swing forward, you create topspin — the ball rotates forward like a rolling wheel. Topspin makes the ball curve downward faster than gravity alone, so it dips sharply onto the table and bounces forward quickly toward the opponent. Backspin (also called chop or underspin) happens when you brush underneath the ball, making it spin backward. A ball with backspin seems to slow down or even bounce backward after hitting the table, making it hard to return.