Why a Tennis Ball’s Bounce Depends on Its Packaging
A tennis ball’s bounce comes partly from gas trapped inside its rubber core. When the ball hits the court, the core compresses and springs back; the trapped gas helps drive that rebound. But rubber is not a perfect barrier: over time, gas molecules can pass through it, and the ball gradually loses pressure and bounce.
The Can Slows That Pressure Loss
A sealed can holds the balls in a pressurized environment. That higher pressure outside the balls reduces the pressure difference between the gas inside each core and the air around it. With less of a difference pushing gas outward through the rubber, the balls retain their playing pressure longer on the shelf.
Opening the can removes that protective environment. The balls do not suddenly go flat, but they begin losing pressure into ordinary air, even if they are not being used. The can preserves the balls’ condition; it does not pump them back up or make their pressure last indefinitely. That is why the familiar hiss is part of the package’s function, not just a sound made when the lid comes off.
