Air Pressure

Air pressure, simply put, is the push that air has against all surfaces that it touches. The more air there is in a contained area, the greater the air pressure. If you have a ball that doesn’t bounce properly, the immediate problem is that it will affect your game.

Air-as in the stuff we breathe-is matter. It has mass, or weight, and volume, meaning that it takes up space. It’s weird to think about air as having mass and volume. You can’t see it, and you don’t sense that you’re running into it as you run or walk. It’s easier to get a sense of air and air pressure when you think of air that is contained within something, such as a basketball, an air mattress, or a bike tire.

Air is composed of different gases, including nitrogen, carbon dioxide, water vapor, oxygen, and others. All of these gases are composed of particles, or more scientifically, molecules, and they’re all in constant motion.

As the molecules move about, they come in contact with surfaces of objects. The molecules push and press on those surfaces, exerting pressure on them.

It’s that pressure that allows a basketball to keep its round shape and remain hard and bouncy. If air escapes from the ball, the pressure inside the ball changes.

Basketballs, along with other objects such as tires and footballs, are high-pressure products. This means that they require a lot of the force created by air pressure in order to get and stay fully inflated.

There are various measurements used for air pressure. Among them are pounds per square inch, millimeters of mercury, atmospheres, and pascals. In the United States, this force is measured using psi, or pounds per square inch. Conventional wisdom is that a basketball needs 8 psi to be properly inflated. A car tire, just for a comparison, needs 40 psi.

Most basketballs have inflation instructions printed right on them. Take a look and you’ll probably see something like “INFLATE 7 to 9 LBS”.

Excessive contained air can cause such force against an object that the object bursts. This happens frequently with balloons, which are fairly fragile. It happens less frequently with basketballs, which are sturdier objects, but it can occur.

A loss of air pressure within an object such as a ball or tire, however, also can cause problems. There is a reason why a ball that’s lost pressure referred to as a “dead” ball in tennis. A dead ball hits the court and drops, as if it is-indeed-dead.