The image above is a rugby ball made by Gilbert, one of the world's largest suppliers of the rugby ball. Here's an inside analyses of the ball.
    The rugby ball is a peculiar piece of equipment. It’s neither slender like a football, nor spherical like a soccer ball; it is somewhere in between. The game of rugby is fast, violent and intense. Players need to pass the ball to one another as fast as they can to keep the ball moving and keep procession. The backs – players on the team who are usually faster and more skilled at the game – have developed techniques over time to use the physics of a rugby ball to their advantage. These include tricks for kicking and throwing the ball. Some of the tricks help fool the opposing players or help your own team. Sometimes, the rugby ball will fool you though. Playing in different kinds of weather will change how the ball will react, as well as if the ball is a different size or not fully pumped up with air. University of New Brunswick Ironmen player Ian Lemoine will help us discover the physics of a rugby ball with his quotes and knowledge from the game.   

The Measurements     
         When you look at a rugby ball, it resembles a football with a rounder, egg-like shape. As Ian Lemoine says: “The rugby ball is rounder and in my opinion better than a football”. Its dimensions are approximately 28cm-30cm in length; 18.5cm-19.7cm in width; has an end to end circumference of 74cm-77cm and a circumference (by width) of 58cm-62cm. This makes it less aerodynamic than a football but its wide berth makes it more stable, so you can’t throw as great a distance but have more accuracy. The weight of a rugby ball weighs between 460g and 410g. This is so that the ball is easy to carry and not as affected by high winds while in the air. These measurements are the characteristics of a normal rugby ball, determined by International Rugby Board (IRB). 
        The shape of a rugby ball is called a prolate spheroid. A prolate spheroid is a spheroid where there’s rotation around the major axis, and the polar axis is greater than the equatorial axis. Prolate spheroids cannot be perfectly spherical and come generally resemble the shape of a football or rugby ball.


The Wind    
         Wind plays a huge role in rugby. The players and the wind determines how far the ball travels after it has been kicked or thrown. The player can control how far it goes by how fast the velocity of the ball is when it goes out of his hands and the angular displacement he throws it at. This is where the wind factor comes in. With the wind at your back, you want to send the ball at a steeper angle. As you increase altitude, the wind gets slightly stronger. This is because the wind has less interference from the earth. If the wind is travelling towards you, it’s best to keep the ball at a smaller angular displacement. This follows the same principle if the wind was at your back. Because there’s more wind at higher altitudes it’s safer to keep the ball low. Now, if the wind was moving perpendicular to the way you’re facing, it’s a different story. “If you want to kick for accuracy, keep it low and out of the strong winds”. For distance or to fool the other team, have a greater angular displacement.       
         Always keep the angular displacement close to 45°. Kick at a greater angular displacement, like 55° if the wind is going the same direction you’re facing. If it’s going the opposite, try for around 35°. However, if you get too far away from 45°, the distance the ball would travel would be greatly decreased.        
         “It’s not always the winds fault; a player on your own team might pass it to you to high. Then when you jump to get it, some guy on the other team might crush you.”
    Here's an example of how
the wind pushed back a rugby ball in the game.

The Aerodynamics     
         When throwing or
kicking a ball, the way in which it is thrown will also affect the distance at which it can travel. This is where the spiral is implied. “Spiral the ball when you want to get it far away from you”. Just like in football, the spiral on a ball will increase the distance of the ball. A spiral happens when the ball is rotating really fast. The spiral works by reducing the amount of air drag that perturbs the ball. Air drag is a natural phenomenon that affects objects travelling through air. “The spiral will always reduce air resistance.” By reducing air drag the velocity of the ball will be increased and the distance becomes greater. It also becomes more stable due to centrifugal force. Centrifugal force is when the energy of a rotating object travels outward, away from the center of the object. This greatly improves the stability of the ball.    
    Here is the proper technique of how to
throw the ball.
        The angle at which the ball is travelling also affects its velocity. If the major axis of the ball is parallel to the ground, the ball will have more velocity due to aerodynamics. The ball is having very little disturbance with the air at this angle. However, if the ball itself is perpendicular to the ground, there will be the most amount of interference with the air. You can measure the speed of the ball by using the equation: Velocity is equal to distance divided by time.
        
 

      
  By having an advanced knowledge of how a rugby ball works, players can make split second predictions on how a ball will move. A player could estimate the height of a rugby ball so that he can run to it as it drops to save time and have more speed before going into contact. The four major variables that determine the velocity of the ball and the distance it will travel are the force with which the player throws the ball, the angle of the throw, the rotation and aerodynamics of the ball, and the wind factor. Ian Lemoine says that you can always see players on the other team who don’t understand the ball because they are often the worst players. By understanding the physics of a rugby ball, players can become better in the game and be more prepared for what the ball has in store for them.  
 

Works Cited
       
BEAN, Alan S.. The Art of Refereeing. A handbook for Rugby Union referees. [For the most part by Alan S. Bean.] Edited by H.F. Ellis and illustrated by Fougasse. London, England: Rugby Football Union, 1956. Print.     

        Freudenrich, Craig, and Ph.D.. "HowStuffWorks "How the Physics of Football Works"." HowStuffWorks "Entertainment". N.p., n.d. Web. 8 Oct. 2013. <
http://entertainment.howstuffworks.com/physics-of-football1.htm>.

        "Kinematics - Physics of Rugby." Physics of Rugby - References. N.p., n.d. Web. 8 Oct. 2013.
http://physicsandrugby.weebly.com/kinematics.html.
          
         Lipscombe, Trevor Davis. Physics of rugby. Nottingham, England:
Nottingham University Press, 2009. Print.
            
         "Physics of Rugby." physics of rugby. N.p., 4 May 2006. Web. 5 Oct. 2013.
http://physicsrugby.blogspot.ca/2006/05/kicking-in-rugby-mathematical.html.

        "Rugby ball." - all about it : dimensions : basics : hold,catch,pass. N.p., n.d. Web. 27 Nov. 2013.
http://www.rugby-sidestep-central.com/rugby-ball.html.

        "Rugby Football." Rugby Football. N.p., n.d. Web. 27 Nov. 2013. <
http://www.shobix.co.jp/jssf/tempfiles/journal>

        "The Physics of Rugby." The Physics of Rugby. N.p., n.d. Web. 27 Nov. 2013.
<
http://www.agard.rugby.hu/letolt/EDZOI/091102ARogbiFizikaja2009160o

        "What's happening to my spinning rugby ball...!." Physics Forums RSS. N.p., n.d. Web. 27 Nov. 2013.
<
http://www.physicsforums.com/showthread.php?t=538267>. 

        "What's happening to my spinning rugby ball...! ." Physics Help and Math Help - Physics Forums. N.p., 11 Oct. 2012. Web. 5 Oct. 2013.
http://www.physicsforums.com/showthread.php?t=538267.
           
        Wilson, Marcus. "The problem with having odd-shaped balls... - Physics Stop." Science & Engineering - Science & Engineering : University of Waikato. N.p., 13 Sept. 2011. Web. 5 Oct. 2013.
<
http://sci.waikato.ac.nz/physicsstop/2011/09/the-problem-with-having-oddsha.shtml>.

And the URLs to our videos
http://www.youtube.com/watch?v=tC_UKiNlii8 for the analyses of the rugby ball.
http://www.youtube.com/watch?v=SiGE7z1OnJQ for how to throw the ball.
http://www.youtube.com/watch?v=LnCTqhVYbBs for wind conditions in a game.
http://www.youtube.com/watch?v=te3VaxCpuik for kicking the ball. 
 

    Physics of the Ball

    Written by Neal Lemoine and Ahmed Naami