Newton’s Three Laws of Motion in Sports
Sir Isaac Newton developed three important principles related to dynamics. We see the application of Newton’s Three Laws of Motion in our daily life and activities. Whether through walking to school or sitting on a chair, these laws are in effect everywhere. Sports are better understood when having a firm knowledge of these three laws, and as we better understand them, it makes more and more sense why certain actions and motions behave certain ways.
Newton’s First Law of Motion
Newton’s First Law of Motion: A body will remain at rest or keep moving at a constant speed unless it is acted upon by a force (law of inertia).
The law of inertia is easily noticeable and applicable in all sorts of situations, including in sports. Inertia keeps an object moving in motion in a straight line at a constant speed or a stationary object at rest. This concept applies to most sports and is crucial in understanding sports movement and techniques.
Examples in Sports
Throwing A Ball
When a ball is thrown and is in mid-air, the only force acting upon it is the force of gravity. If the force of gravity did not exist, the ball would keep travelling at a constant speed until it was affected by an object or if another person touched it. If this ball was thrown upwards, it would end up travelling into space!
Movement of a Puck in Hockey
With the hockey puck, it will glide on the near-frictionless ice when in motion. Although there is some frictional force, it is minimal, so the puck will only come to a stop when it hits another object, including a player and his/her stick, the net, or the boards. Once the puck hits one of these objects, another force is applied to it, changing its direction and speed.
Newton’s Second Law of Motion
Newton’s Second Law of Motion: If the external net force on an object is not zero, the object accelerates in the direction of the net force. The acceleration is directly proportional to the net force and inversely proportion to the net force and inversely proportional to the object’s mass.
What exactly does this mean? Basically no acceleration will occur if the net force acting on an object is zero. In equation form,
Often, there are multiple forces acting on an object, so all forces must be considered when determining the mass and the acceleration of the object in question. Free body diagrams allow us to determine what forces are acting on an object at any given time and provide a visual representation of how these forces are affecting the motion of an object. This law helps us mathematically determine the acceleration objects experience, such as the acceleration of a hockey puck once it has been passed or shot. As well, it helps us determine other quantities in kinematics, such as velocity, displacement, and time.
Examples in Sports
Tennis
In tennis, the acceleration of the player’s racket will allow a maximum amount of force to be applied to the ball, which in turn will travel at speeds up to 160 mph!
Throwing a Ball
Newton’s Second Law applies to throwing a football, baseball and basketball. If the same amount of force is applied to each ball, a baseball will have a much greater acceleration than a football with all else being equal. This is because the mass of the football is more than three times greater (397–425 g) than a baseball (142–149 g). However, if a basketball was thrown with this same force, the football would travel further than the basketball since the basketball weighs more (624 g) than a football. Although the size and shape of the ball matter as well, more force would have to be applied to the basketball and football for them to have the same acceleration as the baseball and travel close to the same distance as the baseball.
Newton’s Third Law of Motion
Newton’s Third Law of Motion: Every action has an equal and opposite reaction.
Newton’s third law of motion is also known as the action-reaction law. applies in all sorts of scenarios in sports, and some sports will rely on this concept more than others.
Examples in Sports
Golf
This law is the basis of golf, as the golfer swings his/her club to hit a motionless ball and send it into flight. During impact, the club is applying force to the ball. At the same time, the ball is pushing back with an equal and opposite force. However, it is not very noticeable because of the difference in mass between the ball and the club. Although the club will slow down a little due to the ball applying force back to the club, it is a minimal decrease in speed.
Body Contact in Sport
In football or hockey, lots of direct hitting is involved. When a larger player hits a smaller player, the larger player feels the same force being applied to him as the smaller player, and this force will slow the larger player down (instead of skating right through the smaller player). Although these examples differ in terms of sport and action, they still fall under Newton’s Third Law.
