Physics Internal Assessment



How does the radius of a soccer ball affect the rebound height of a soccer ball after one bounce?



Ricardo Olguin Galeana



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Table of Contents

1.     Topic

2.     Introduction

3.     Materials

4.     Picture

5.     Procedure

6.     Raw Data

7.     Data Processing

8.     Data Presentation

9.     Conclusion and Evaluation

(Related Links)








Lab Report

        I.            Topic .:. Top

The effect that a radius has on one bounce a soccer ball has


      II.            Introduction .:. Top

A radius is a length from the center of a sphere or circle to the edge in a straight line.  It is the most common way to measure a sphere or circle.   How does the radius of a soccer ball affect the rebound height of a soccer ball after one bounce? The independent variable is the radius of a soccer ball, and the dependent variable is the height of a soccer ball after one bounce. The controlled variables were type of soccer balls, surfaced that was used to bounce the balls, the air pressure in all of the balls, same measuring format, the distance the ball fell, the person timing, the mass of the planet the experiment was conducted on, and the timing device, as well as the same video recording tools which means the same videographer. If we increase the temperature of corn syrup, then the viscosity will decrease because of the attractions between the molecules weakening as the temperature increases.


    III.            Materials .:. Top

A.    One Size 3 Soccer Ball(Nike)

B.     One Size 4 Soccer Ball(Nike)

C.     One Size 5 Soccer Ball(Nike)

D.    Manometer

E.     Two Meter Sticks

F.     Video Camera

G.    Flat Concrete Surface

H.    Information on the sizes of the soccer Balls used

I.       Tape

J.       Wall(must be flat and touching the concrete surface)











   IV.            Picture .:. Top




V.    Procedure .:. Top

     1.            Gather Materials

     2.            Discover the radius of the soccer ball being experimented upon. 

     3.            Find a flat wall that's at least two meters in height

     4.            Tape both meter sticks on the wall, vertically, and above one another

     5.            Use the Manometer to measure the pressure in all the soccer balls to make sure they are constant. 

     6.            Decide a height in which you will drop the Soccer Balls from; has to be below two meters(we used 1.5m)

     7.            In Front of the meter stick the ball must be dropped

     8.            Hand the video camera to someone and record the dropping of the ball and the highest bounce

     9.            Write down data

10.            Take Average

11.            Repeat steps 2-10 for all sizes of the balls








VI.    Raw Data .:. Top

VII.   Data Processing .:. Top

To process the Data we had to combine several different equations in order to find the effect of the radius of a bounce in a soccer ball. We put the area of a sphere equation (A=4πr^2) and filled the rest with the information acquired from the Nike website which can be found in the Bibliography regarding the area of their soccer balls used.  It would have been illogical to cut open soccer balls just to measure the radius, then they would be ineffective for the experiment.  Once the area was acquired, we worked backward from the area formula to discover the radius of the soccer balls.  Once all of our trials were complete we used the mean formula (( Σ xi ) / n) to have a more concrete point of interest. 


VIII.   Data Presentation .:. Top


Data File: Text  .:. Excel


IX.      Conclusion and Evaluation .:. Top

Upon conducting our experiment, we came to the conclusion that increasing the size of a soccer ball which in this case was measured by the length of the radius will decrease the height of a bounce because of the fact that the pressure in a more condensed space will build more energy reacting in a bigger bounce, backing up our hypothesis. This is due to the smaller surface area the ball with a smaller radius contacted making the ground react with a greater force.  This is due to Newtons Laws that states that any object in motion will stay in constant motion unless acted upon by a different force.  In this case, the soccer balls did not reach their dropping point because there are many other forces acting upon them like gravity and wind resistance.  If we were to put them in a vacuum and with no gravity having any effect on them whatsoever, they would reach the 150 cm easily When the ball with the smallest radius which was 9.5 cm was dropped from the height of 150 cm, rebound height was on average 126.33 cm. When the radius was increased to 11.5 cm, the height on average became 112 cm, a significant decrease.

Simply put, there were a lot of sources of error in our experiment. First off, a large assumption we made was that the temperature of the atmosphere would not have any effect on the pressure within the soccer ball, which it shouldn't, however; the balls might lack insulation making this a source of error.  That meant that the pressure was more or less depending on the temperature.  In addition, the balls have been used before making them potential to more defects.  Since there is no way of measuring this the balls could vary from quality.  This error is hard to avoid, but we tried our hardest by using a controlled environment and by trying hard to measure the bottom of the soccer balls. We also tried making sure they all started with the same PSI which in this case was 8.5psi.  Also, there is a large source of error in the video making progress to measure the height.  Perspective could have played a big role in this case.  Since the measurement was taking from the video itself, this could lead to reading the meter sticks wrong. To avoid this error, we had the same person take the video and a different person read the video notes to see the heights.  Another source of error is that recording was taking outside, therefore, leaving the data to the potential wind resistance factor.  This could have affected the data in both ways.  One way is that it prevented the ball to bounce to its maximum height because of said resistance.  Another potential way wind resistance had an effect could have been that it could have raised the height more than usual.  This is more probable with the smaller ball because it is relatively light.   To avoid this error, we tried to keep the distances pretty small so that the wind would not have as much time to affect the balls.  Before each trial, we measure the PSI of each ball to try and keep that constant. 

In the end, we are fascinated with how the size of soccer balls have an effect on the height they bounce.  Now it makes more sense why you see little kids playing with smaller balls, not just because they are smaller but because they can easily find amusement in the bounce height of the soccer ball.  Meanwhile, a soccer ball that bounces less is essentially easier to control with your feet which may be a factor of why they use bigger soccer balls with adults.  This experiment was entertaining because I am a big supporter of the game of soccer. 


   Related Topics .:. Top

This link is a article regarding the elasticity of a soccer ball.

A simple QnA regarding the question: if soccer balls are affected by gravity.

An experiment regarding bouncing with an extra bounce doe some reason.

An article regarding the compressibility of certain sports balls.

 Article regarding bouncing balls; specifically, the bouncing of a ball and its correlation with physics. 


Bibliography .:. Top


“ Size Fit Guide - Soccer Balls.” NIKE, Inc.- Inspiration and Innovation for Every Athlete in the World.,