Physics in Football

Physics of Football

            Physics and math appear to be omniscient essences that surround everything we do, from putting on our shoes to landing a probe on a comet 3 million miles away. They are also present in some popular activities throughout the country. Football is arguably the most popular and exciting sport in America. Its intense, fast-paced action combined with the “Wow” and “Ow” factors of full-grown men tackling each other make this sport enjoyable and highly technical. There are several factors that go in to being a successful football player; the main factors that help the most are height, weight and speed. These factors largely make up the key variables in the physics behind football. This post will mainly focus on the presence of newton’s laws in football and to make them more easily understood, each law will pertain to a certain type of player.

            Newton’s first law states that an object in motion tends to stay in motion and that an object at rest tends to stay at rest unless acted on by an outside or opposing first. It is called the law of inertia. Inertia refers to an objects ability to resist movement. The age-old question, “what happens when unstoppable force meets an immovable object?” deals with the law of inertia. Newton defined force (F) as being equal to the product of the object’s mass (m) and acceleration (a). Given that this object is being defined as immovable that must mean that the acceleration of this object is 0 for any given force. If we solve for acceleration in Newton’s F=ma, we get a=F/m. In order to satisfy a=F/m for a=0 and F=constant the mass must approach infinity. Meaning that this object is incredibly dense and/or large. If the law of inertia were to be heavily, no pun intended, applied to one group on the football field it would be the linemen. Coaches want their linemen to be big and physical players so that they can make room for a run or push forward and get the quarter back. The bigger the lineman, the more force the opposing lineman must apply to get through the line. Granted, NFL linemen are fully capable of moving so there was no intention for them being the solution for an immovable object.           

            Briefly stated in the previous paragraph is Newton’s second law; F=ma. This equation is used in every facet of the physics world and is the parent of many other important equations in physics. E.G., Torque, kinetic energy, momentum etc. F=ma can be applied to every single portion of the game of football and contains countless examples. Rather than using the basic F=ma equation for an example, we will be using one of the equations based on force, torque. Torque is the product of an objects force and a radius (T=Fr). With this equation the positions of kicker and punter will be put to the test. For the sake of simplicity all of the players will have the same acceleration and that a bigger value of T means the ball will travel further. If we dissect the torque equation we get:

T=Fr

   =(Mass x acceleration)(radius)

The radius in this case will be defined as one half the height of the player. Given that the acceleration is constant, which of the following players would the coach recruit to be his kicker?

               A)   5’8” 205lbs

               B)   6’0” 190lbs

               C)   4’8’ 250lbs

The answer is oddly C. Now this was just an example to portray the direct relationship between length and mass (also, let it be noted that pounds [lbs] is not a measure of mass but it was used to simplify the examples). It would be hard to believe that a 4’8” 250lb person would be in the NFL. If further examples are needed to understand the idea of torque, try this one at home:

Find a spinning office chair and have a friend spin you around. As you spin move your legs in and out and you will feel yourself speeding up and slowing down. This change in acceleration is thanks to Torque. Torque was defined as (mass x acceleration)(radius). Your friend spun you with a constant torque. Seeing how while you are spinning that you do not lose weight, if you decrease your radius, the length of your legs sticking out, then the only way for torque to remain constant is for your acceleration to increase with a decrease in radius and vice-versa for sticking your legs back out.

Newton’s third law states that for every action there is an equal and opposite reaction. This means that if a linebacker hits a running back with a force of 1000 newtons, newtons being the measure of force, that he and the running back will both feel the effects of that hit of 1000 newtons. The developers of the safety equipment used in football take into account the incredible forces the players incur while playing when they make the protective gear. The shoulder pads in football can reduce the force put onto the body by as much as 50% and the helmets are designed to absorb even more force making football a somewhat less dangerous sport.

            Football is a highly complex sport when you look at the math behind it; it is way more complex than a 1200 word essay could possibly fit without getting extremely technical. Nonetheless, the fundamentals of physics are abundant in the game of football and I hope I have enlightened you even in the slightest.

1, Chapter. Newton’s Laws, Chemical Kinetics, ... (n.d.): n. pag. Web.
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