The Physics of Rugby

 As a rugby player, I have been really curious as to how physics relates to passing and kicking during the game. After taking physics 111, it seems that kinematics and forces can be used to explain the motion of the rugby ball during a pass and a kick, as well as the motion of players during a scrum and tackle. During passing, the key is to get the ball to your teammate as fast and as straight as possible. 

Newton’s First Law of Motion states that an object at rest will remain at rest and that an object in motion will stay in motion unless acted upon by an unbalanced force. Newton’s First Law of Motion is seen in Rugby when a player kicks the ball. Before a player kicks the ball, the ball is at rest and will remain like so until an unbalanced force (the players foot) acts on it. Once the ball is kicked, it will go up into the air until an unbalanced force acts upon it, which in this case is the force of gravity which will cause the ball to come back to the ground. The horizontal speed of the ball will remain constant as only gravity acts constantly upon the ball (assuming air resistance is negligible), but the vertical velocity will change. Additionally, forces are involved when a player catches the ball. When a ball is kicked and a player is in position to catch the ball, they will apply a force that is equal and opposite to the ball. Lastly, Newton’s First Law can be used to explain the forces that occur during a scrum (see above photo for reference of a scrum). During a scrum, two sets of players will push against each other usually with the same amount of force. Thus, the scrum would not be moving and would be at rest. The scrum will remain at rest until one side of the scrum pushes the other players with a greater amount of force to push the other team backwards. 

Newton’s Second Law of Motion is also seen in rugby when a player tackles an opponent. Newton’s Second Law of Motion states that force is equal to the mass times the acceleration. Thus, when a player runs towards an opponent, they have a certain mass times acceleration (F=ma). This means that the larger the player’s mass is, the larger the force they will have. If a player has a greater force as a result of their large mass, they will be able to hit their opponent with greater force and will be able to tackle their opponent. Additionally, the faster the player’s acceleration, the larger the force they have. Thus, it is important to be both heavy and fast in rugby if you want to make good tackles. 

 

References:

https://pdfs.semanticscholar.org/204d/e75fab5746a27948662c6274b7afdc67865e.pdf