Download Forces in Football

Forces in Football
In math and science a force is described as an influence that is inclined to change the
motion of an object. Everyone has a basic understanding of the concept of a force from
everyday experiences such as pushing a door open or even picking up a pencil. Because
only a force can cause a change in velocity, we can think of a force as that which causes
an object to accelerate. A force is a vector (discussed in an earlier module). Several
forces acting on a football or any object simultaneously is said to have a net force acting
on it. A net force is the vector sum of all forces acting on the object. If the net force
exerted on an object is zero, the acceleration of the object is zero and the velocity remains
constant. Forces are measured in Newton’s (kg m/s2) using the SI units, and measured in
Pounds of force using the U.S. customary units.
Newton’s Laws under ordinary conditions describe the action of forces in causing
motion. Discussing each law and its parameters encourage football enthusiast to
appreciate the quality of performance each athlete brings to the field. An athlete can also
benefit from these laws by respecting the laws to prevent injuries, and focus training on
strength and power to increase his quickness and speed. Newton’s laws have given
football affiliates a better understanding of how much stress an athlete endures. Sport
equipment manufacturers have also benefited from this science and have developed more
enhanced and safer equipment for athletes, therefore improving an athlete’s performance.
Picture of a fan being enthusiastic + Picture of football gear/equipment
Newton’s First Law (Classical Physics)
Newton’s First law of motion, sometimes called the law of inertia, defines a special set
of reference frames called inertial frames. If an object does not interact with other
objects, it is possible to identify a reference frame in which the object has zero
acceleration. Newton’s first law states that an object will continue at rest or in motion in a
straight line at constant velocity unless acted upon by an external force. The tendency of
an object to resist any attempt to change its velocity is called inertia. This law is very
simple, but very elegant. A football player sprinting down the side line, will continue
running down the side line to the end zone, unless a force (another player) acts upon him
(tackles him).
Picture of a football player running in a straight line with no forces
Newton’s Second Law (Classical Physics)
Newton’s first law explains what happens to an object when no forces act on it. It either
remains at rest or moves in a straight line with constant speed. Newton’s second law
answers the question of what happens to an object that has non-zero resultant force acting
on it. When viewed from an inertial reference frame, the acceleration of an object (a
football or athlete) is directly proportional to the net force acting on it and inversely
proportional to its mass. This relationship can be mathematically represented by the
following equation that reads force is equal to mass times its acceleration.
F  ma

If we consider a team’s offensive line (five man set), we will conclude that each
lineman weighs close to 305 lbs, totaling1525 pounds or approximately 765 kg in total.
These athletes have to exert enough force off the ground to give them an acceleration of 7
m/s2. The force required by the offensive linemen in total will equal almost 5000
Newton’s or 1100 pounds. That is more than half a ton! The athlete in the following
picture must be able to generate enough force to pass through the arms of a defender. His
mass is a constant and does not change during the play, so he will have to rely on how
fast he can accelerate to generate a large enough force to drive him to victory
Picture football-run3 (desktop)
Newton’s Third Law
If you press against a corner of desk with your fingertip, the desk pushes back and
makes a small dent in your skin. If you push harder, the desk does the same and the dent
in your skin is a little larger. This simple experiment illustrates a general principle of
critical importance known as Newton’s third law. This law states that if two objects
interact, the force F12 exerted by object 1 on object 2 is equal in magnitude and opposite
in direction to the force F21 exerted by object 2 on object 1:
F12 = - F21
It is frequently important to designate forces as interactions between two objects. The
subscript notation will be implemented, where Fab means, “the force exerted by a on b”.
The third law, also states that forces always occur in pairs, or that a single isolated force
cannot exist. The force that object 1 exerts on object 2 may be called the action force and
the force of object 2 on object 1 the reaction force. Either force can be labeled the action
or reaction force. In all cases, the action and reaction forces act on different objects and
must be of the same type.
Does Newton’s law hold in a collision between a small running back and a large
offensive guard?
Picture of a good tackle
Yes, his law will hold. Although the smaller running back fly’s backward immediately
after the collision, he still exerts an equal but opposite force on the larger offensive guard.
The reason the smaller athlete is sent flying backwards is because his mass is smaller.
Quickness, Speed, Power, and Strength
Quickness  related  Strength
Speed  related  Power
A football athlete is said to be quick if he can accelerate rapidly to a given speed.
Newton’s second law states that “F=ma”, and if the athlete has a large strength he can
give a strong acceleration. Speed is known as a velocity or how fast a football player can
run. This requires power, or the ability to exert a large force at high speed. Power is
effective for superior tackling. That is why coaches mandate tactical training sessions in
the weight room and on the field to increase an athlete’s strength and power.
Picture of training