Soccer Ball Flight Distance & Inflation

Sometimes soccer playing students use the question of inflation pressure versus flight distance as their Science Fair project, and so the following is offered to provide some relevant information.

The biggest challenge in such an experiment seems to be imparting a consistent force to the ball (same amount of force, applied to the exact center of the ball). I have heard some students have constructed a kicking machine for the testing. Our results weren’t conclusive, hopefully your student players will have better success.

In soccer we both want the ball to travel far and to have a playable touch (we don’t want it so hard it hurts the player, and we don’t want it bouncing off our foot without control). In light of this, the soccer ball inflation pressure is specified in the international rules (FIFA Laws of The Game, Law 2 – The Ball) as are certain other parameters the ball must meet. Most often ball inflation is checked before a match by feel, meaning the referee squeezes the ball to determine its suitability.

There are a variety of ways to construct a soccer ball and while 12 psi inside one ball is the same as 12 psi inside a different ball, the feel of the ball may differ due to construction features such as layers of covering, covering material, extra padding, and the type of air bladder. Latex rubber air bladders are generally considered to give a superior “touch” compared to butyl rubber bladders.

The result is that a referee (or player) may use a higher inflation pressure in a ball constructed to have a softer “touch”.

All other things equal, the more air pressure in the ball, the further it will travel upon impact due to increased elasticity in the gas within the ball. It would seem that different ball construction, though, might influence the transmission of forces.

MLS and other leagues are required to follow FIFA Laws of the Game. Law 2 – The Ball currently reads:

The ball is:
• spherical
• made of leather or other suitable material
• of a circumference of not more than 70 cm (28 ins) and not less than 68 cm (27 ins)
• not more than 450 g (16 oz) and not less than 410 g (14 oz) in weight at the start of the match
• of a pressure equal to 0.6 – 1.1 atmosphere (600 – 1,100 g/cm2) at sea level (8.5 lbs/sq in – 15.6 lbs/sq in)

If your own scientist players investigate and experiment, perhaps they can share their discoveries with the soccer world here. Good luck!