Do Tennis Balls Float Is A Question Many Have Asked

20200713 094532

Do tennis balls float? Yes they do. Visit us to know the science behind this floating and what can cause a tennis ball to sink. We have all the details

The first thing you should know is that you can absolutely use tennis balls for many different things, not only to play tennis on the court, but also for playing with your cats or just throwing at each other at the park for fun.

Tennis balls can also be placed on the bottom of a walker to aid the person in walking. Walkers with tennis balls help those people who are only able to slide the walker forward rather than lifting it and placing it on the ground and they provide a greater surface area than the regular rubber tips present on the walker and also better stability.

The history of tennis balls

Let us briefly get into the history of tennis balls. Tennis balls have their origin from way back in the 15th century. In the 15th-century tennis balls were created out of leather and they were then stuffed with horse hair,  human hair or wool. If leather was not available, it was even common to use the inside stomach of a goat or sheep. This was then stuffed with wool and tied up with a rope. However, the Germans were a step ahead and were known to create air-filled rubber balls. We have surely come a long way from all that and now we use tennis balls that are compacted with air, a hard rubber core and covered in a fuzzy material.

This fuzzy tennis ball covering is known as the nap and it is a  textile material that is normally made of wool, nylon, and cotton is cut out in the shape of a dumbbell and then two such dumbbell shaped pieces are glued over the ball. This fuzz covering is integral to the tennis ball because It not only changes the speed of the tennis ball but also imparts spin to it as the ball travels through the air and if the fuzz is not intact over the tennis ball, then the tennis ball will travel much faster in the air and will almost always land outside the tennis court.

There are lots of people who constantly asked what will happen if they throw the tennis ball in the water, will it sink immediately after making contact with the water or will it float on top? That’s exactly what we will be discussing in this article today.

Do tennis balls float? Yes tennis balls do float in water and the reason behind this is because it is hollow and filled with air, which cause it to have more density than water. It is safe to say that all objects that have more density than water will eventually float on top when thrown into the sea or pool.

Why Tennis Ball Floats on Water?

Do Tennis Balls Float

The number one reason tennis balls float on water is because of the ball being more dense compared to the water, which means that the ball has positive buoyant. If you’re a science savvy like “myself” then you’ll know that when an object is buoyant, it will float on water.

Another reason behind the floating of the tennis balls is because they are filled with air, which cause it to be dense. You should also keep in mind that the force caused by the water pressure is much stronger than the force of gravity pulling down the tennis ball. As mentioned earlier, tennis balls are known to be hollow and even has a thin layer of rubber, which is considered to be a lot more dense than the water and causes the ball to float.

Let’s make it clear that not all tennis balls are filled with air. There are some that people refer as pressureless tennis balls and these balls are becoming more popular on the market as the days goes by. Also, the sad part is that these pressureless will not be able to float in water because aren’t filled with air, like the original tennis balls. Therefore they have a positive buoyant, which will cause the tennis balls to sink whenever it makes contact with the water.

Physics Behind Tennis Ball Floating

20200713 094555

Science savvy should know that if the weight of an object is less than the weight of the displaced fluid when it’s completely submerged, so if the object has an average density that is less than the fluid, when it is completely submerged it will experience a buoyancy force that is known to be greater than it’s own weight.

Buoyancy is just a force, pushing towards. There are two types of buoyancy, these include positive buoyant and negative buoyant. Whenever an object float in the water it is said to be an positive buoyant. While an object that sink upon reaching the water is an negative buoyant. In order to determine an object buoyancy, you must first take its mass and volume into consideration.

As mentioned earlier, a tennis ball have way less density than water and because of this tennis ball have a positive buoyant and this is the number one reason why it floats on water. If any form of objects have more density than water, it has a negative buoyant which makes it sink. For example, a golf ball, or a metal fork will have negative buoyancy in a bowl of water allowing it to sink to the bottom.

It’s the same that applies if you were to use a foil boil. Because they are usually known to be crumbled into a tight clump, that has more density due to the fact that its pennies are packed together into a smaller space than those in the foil boat. The boil boat is expected to have way less density because it is spread out and filled with air, just like the tennis ball. As you can see, all objects float when they have less density than water, but sink when they have more.

Nowadays, you can expect most tennis balls to be pressurized, which means that the balls are completely filled with air. And by now you should know that air is more dense than water and that is why the ball will float whenever it reaches the water. However, with pressureless tennis balls, you will noticed that there isn’t any air filled within the ball. Which lead to a negative buoyant and the ball will not sink upon contact with the sea or your outdoor pool.


If you want to play with your tennis ball at the sea or simply at your own pool, make sure to get a regular tennis ball that is not pressurized. Using a regular tennis ball that is pressurized will prevent the ball from sinking upon contact with the water. But, remember if you play with the ball with your cat and they tear the rubber, the air will be released from the ball which will result in it sinking.

With that being said, tennis ball can be a great object to not only throw around while at the sea or in the pool, but also something for your cat to play around with in the house or backyard. However, according to many online news source, you shouldn’t let your cat ripped it apart and swallow the rubber. This can lead to serious problems such as tooth pulp and even death if the cat mistakenly swallowed the rubber for food. So take all of this into consideration before giving your cat the tennis ball to play without your supervision.

Now that you know everything about tennis ball and floating, you can go ahead and play around with it in the water. As stated before, tennis ball are not only a object for cats, but a fun water activity to just toss around with your friends and families on the beach or at the pool. As long as you don’t waste your time playing with a pressureless tennis ball, there is absolutely no reason to worry about the ball sinking.

Gaurav Mongia

Welcome! We are a passionate group of writers and researchers who enjoy writing about tennis racquets, tennis balls, and other tennis equipments. We hope you find this guide helpful.

Recent Posts