Q & A: Soccer ball sizes

Q:
If I bought 3 soccer balls the same brand/maker in 3 different sizes (Size 3, 4 & 5). Does the size of a soccer ball affect how many times it will bounce? It is true that the bigger the ball the more it will bounce due to the more air particles in it? Thank you in advance for your help.
- Destiny (age 11)
Irvine, CA
A:
Hi Destiny,
The differences in the three sizes you mention 3,4, and 5 are only related to the diameter and weight of the balls.  For your age group the recommended size is 4.  There is no distinction in the amount of bounce-per-ounce.  The bouncibility of a ball has to do more with the construction materials than its size.  There is a small effect due to the air pressure inside of the ball.  The FIFA organization specifies that the internal pressure of regulation balls be between 8.5 and 15.6 atmospheres.  It doesn't mention the requirements for the smaller sizes.

LeeH

(published on 10/12/2011)

Follow-Up #1: More on soccer ball bouncing

Q:
Hi I have a follow up question. My question was about if different size soccer balls will bounce more, less or the same. If I understood the answer, it means that there would be no difference between bounces if they were all made of the same material? No matter what size?
- Destiny (age 11)
Irvine, ca
A:
The 'bounce-ability' of a ball is a measure of rebound height.   Technically, it's related to the 'Coefficient of Restitution' , CR.  What you do is do drop the ball from a well known fixed height H1 and then measure the height of the rebound, H2.  Then CR = Sqrt(H2/H1).
In some sports the CR is well defined and the balls must conform within a certain range. In tennis, for example, a tennis ball when dropped from a height of 100 inches must rebound between 53 and 58 inches.     I do not know of any such rule in soccer, so what you sees is what you gets.  Again slight differences in construction  or internal air pressure or even temperature will affect this.   The only way to determine the answer is to compare two different balls side by side.
As an experiment you might take your favorite soccer ball and pump up the air pressure to several different values and see how far the ball rebounds when dropped at a standard height.

LeeH

(published on 10/13/2011)