Photograph by Scott Cunningham/National Basketball Association
In fall 2006, the National Basketball Association (NBA) started using basketballs made with synthetic, or manmade, material instead of leather.
They made the switch because they wanted every basketball they use to feel and bounce the same. Not all leather balls are exactly alike in weight or how they bounce, but the synthetic balls are.
However, some players complained right away that the new balls bounced differently and were actually harder to control than the leather ones.
Dallas Mavericks owner Mark Cuban asked for help from the Department of Physics at the University of Texas in Arlington, Texas. Why ask scientists about basketballs?
“In physics, you can learn about the properties of everyday things—like basketballs,” says James Horwitz, one of the physicists who worked on the project. Physics helped answer questions about why the new balls handled differently.
For example, the scientists investigated friction, a physical property that in this case affects the ability of a player to hold onto a ball. “The greater the friction, the better it will stick to his hand,” explains Horwitz.
Tests on both wet and dry balls showed that while the plastic ball was easier to grip when dry, it had less friction and became much harder to hold onto when wet.
That’s because perspiration stays on the surface of the synthetic balls but gets absorbed into the leather balls—an important detail for sweaty athletes.
The researchers also tested bounce and found that the logo printed on the new balls made their surface uneven and caused them to bounce a little strangely compared with the leather balls.
In January, the NBA went back to using the traditional leather balls. They aren’t perfect, but for now, that’s just the way the ball bounces.
- It takes the hide of one whole cow to make four leather basketballs.
- Leather balls absorb moisture eight times faster than the synthetic ones.
- Because it absorbs so much sweat, a leather ball may increase its weight by 10 percent during a game, but a synthetic ball remains the same.