Why Do New Tennis Balls Go Faster?

Some say that new tennis balls go faster because the fluffier they are, the more aerodynamic they become. Let’s take a look at the science behind this claim.

Introduction

In 1873, Major Walter Wingfield patented a game called “sphairistike.” It was an outdoor game played on an hourglass-shaped court with small netted rackets and a soft, bouncy ball. The game quickly became popular in England and, by 1874, tennis was being played on public courts all over that country. A few years later, the game spread to America where it became just as popular.

The game has evolved quite a bit since its early days. The net is now 3.5 feet high at the center (it used to be only 3 feet high), and the ball has changed as well. Early tennis balls were made of leather and stuffed with feathers. They were quite hard and didn’t bounce very well. In fact, one story goes that players would often have to hit the ball several times just to get it over the net!

Today’s tennis balls are much different. They are made of rubber or synthetic rubber (like nylon), and they are filled with air or gas (usually nitrogen or hydrocarbon). This makes them much softer than early balls, and they bounce much better too. In fact, they bounce so well that you might think that all tennis balls would bounce identically. But they don’t.

One reason for this is that different manufacturers make different types of balls. Some are designed to be used on slow surfaces like clay courts while others are made specifically for faster surfaces like hard courts or grass courts. Another reason is that Balls can actually vary quite a bit in quality, even if they’re made by the same manufacturer and intended for the same type of surface.

The Science of New Tennis Balls

When you open a can of new tennis balls, you might notice that they have a strong smell. This is due to the Volatile Organic Compounds (VOCs) that are emitted from the balls. VOCs are also responsible for the new-ball effect in tennis. When a can of new tennis balls is opened, the VOCs inside escape into the air and make the balls more bouncy. This increase in bounciness makes the ball travel faster and also makes it spin more.

The Coefficient of Restitution

The coefficient of restitution is a number that represents how much energy is lost when two objects collide. It’s usually represented as a decimal between 0 and 1. A perfectly elastic collision would have a coefficient of 1, meaning that no energy is lost when the objects collide. An inelastic collision would have a coefficient of 0, meaning that all the energy is lost when the objects collide. Most real-world collisions fall somewhere in between these two extremes.

One way to think about the coefficient of restitution is to imagine two identical Ping-Pong balls. If you drop one ball from a height of one meter onto a hard surface, it will bounce back up to a height of about 0.9 meters. The other ball is placed atop a compression spring. When you release the ball, it will compress the spring and then bounce back up to a height of about 0.9 meters. In this example, both balls have the same coefficient of restitution (about 0.9).

The coefficient of restitution can be affected by several factors, including temperature, surface roughness, and material stiffness. For example, a tennis ball with a lower coefficient of restitution will compress more upon impact and lose more energy than a tennis ball with a higher coefficient of restitution. This means that the lower-coefficient ball will bounce lower and slower than the higher-coefficient ball.

One common method for measuring the coefficient of restitution is to drop a steel ball from different heights onto a hard surface and measure how high it bounces back up. The higher the bouncing steel ball’s final height, the higher the coefficient of restitution

The Effect of Temperature

The effect of temperature on the speed of a tennis ball has long been a topic of debate and scientific study. While it is generally accepted that the cold can slow down a tennis ball, there is less consensus on how much of an effect temperature has on the speed of a ball.

One study, conducted by the American Sport Products Group, found that a tennis ball’s bounce was reduced by about 17 percent when the temperature dropped from 77 to 55 degrees Fahrenheit. Another study, conducted by Tennis magazine, found that balls lost around eight percent of their bounce when exposed to freezing temperatures.

So what explains these differences? It’s likely that both studies are measuring different things. The American Sport Products Group study was looking at how much lower a cold tennis ball will bounce, while the Tennis magazine study was looking at how fast a tennis ball will lose its bounce after being struck.

It’s also worth noting that both studies were conducted with new tennis balls. It’s possible that older balls are more affected by temperature than new ones. In fact, one study found that used balls lost more than twice as much bounce as new balls when exposed to freezing temperatures.

All of this research suggests that temperature does have an effect on the speed of a tennis ball, but it’s likely not as big of an effect as many people think. If you’re looking to improve your game, you’re better off focusing on your technique than worrying about the weather conditions.

The Difference Between New and Used Tennis Balls

The assumption is that new tennis balls are faster because they have less bounce. However, this is not the case. New tennis balls actually have less bounce because they are so tightly wound. The stringing on a new tennis ball is also tighter, which makes the ball go faster.

The Effect of Wear

As a tennis ball is used, its surface slowly wears down. The felt fibers that cover the ball start to break off, revealing the underlying rubber. As more and more of the fiber cover is lost, the ball’s surface becomes rougher. The rougher surface produces more friction when the ball hits the ground, which slows it down. In addition, as the felt fibers are lost, the ball becomes less bouncy and doesn’t spring back as much when it hits the ground. The loss of bounce also makes the ball slower.

The Effect of Dirt and Grime

Dirt and grime can have a big impact on the performance of a tennis ball. Even a small amount of dirt can cause the ball to spin erratically and lose speed. When a ball is new, its surface is clean and smooth, allowing it to travel through the air more easily. As the ball gets older and dirtier, its surface becomes rougher, which makes it more difficult for the air to flow around it. This causes the ball to lose speed and spin erratically.

Conclusion

While there is a difference in how fast new and old tennis balls bounce, it is not enough to affect the game. The type of court surface, the weather conditions and the age of the ball all play a role in how fast the ball will bounce. A new can of tennis balls may have been sitting on a shelf for months or years before it was purchased, so even a “new” ball may not bounce as high as one that is freshly sewn.