Physics Honors Project
Laredo Community College
Dr. O. Patricio
THE STUDY OF NEWTONS LAWS OF MOTION
Paula I. Rios
June 27, 2017
Sir Isaac Newton was born in England in 1643 and is famously known today for his dedicated works and contributions to the science of physics and the study of mathematics. As a boy, Newton was actually pulled away from his education because his mother wanted him to be a farmer. As his education was not continuous, he soon went back to finish primary school, and not long after that, joined University of Cambridge’s Trinity College in 1661. At the beginning, he was interested in classical curriculum of the university but later he was fascinated by the works of certain scholars such as Rene Descartes. Newton returned home in 1665 as the result of the great plague. Though forced to go home, Newton continued to study about the theories on calculus, color and light. In this time, he worked on different theories and it is said the famous incident of the falling apple occurred during this time which inspired him to formulate the theory of gravity. During his studies on the concept of motion, Newton created (formed) three concepts which have been tested over and over by other scientists and philosophers. They are found to be solid and unchangeable. These laws which are applicable to motion of physics are called Newton’s Three Laws of Motion. The purpose of this paper is to discuss the theories of the motion and their application in the day to day life.
The three laws of motion is a main part of physics which governs most of the activities related to motion. The actions and outcomes of the objects related to motion can be clearly described and identified with the application of these laws. The literature review section will cover all the aspects related to the laws and its applications.
According to Newton’s first law of motion, also known as the law of inertia, an object should be at the state of rest or moving towards a particular direction without changing its speed or the direction. These states are stable and cannot be changed unless applying an unbalanced force on them. In other words, nothing will happen if there is no interference, and the object will stay at rest; vice versa, if an object is going towards a certain direction with a certain speed (assuming maintained forever), it will not be disturbed. An object is still or moving towards a certain direction at a constant velocity.
Video footages of space missions can give support to this theory. Since there is no gravitational pull, objects in space stay where they are kept. There is no interfering force to change the balance of the force applied on these objects. When an astronaut throws an object, these objects move at a constant speed and their motion is continuous.
In the first law, the behavior of the objects are considered when all the pertaining forces are equal or balanced. According to that, there is not an acceleration when the forces are balanced for an object. The acceleration of the object is equal to 0 m/s^2. The second law helps to develop the first law by introducing the particular forces necessary for the process of changing the velocity of a respective object. According the second law, there is an acceleration when there is an unbalanced force. This force can change the direction or the speed of the object and can possibly change both.
The acceleration of an object is based on two variables which are the net force and the mass of the object. The acceleration of the speed is directly connected with the strength or the impact of the net force which is applied on the object. The acceleration inversely affects upon the weight or mass of the respective object. When the net force increases, the acceleration also increases and when the mass is increased the acceleration decreases.
F= M x A
The acceleration is the necessary aspect, so we can change the formula as followed:
A = F/M
For example, a car weighs 1000 kg and a man applies a force which gives the car an acceleration of 0.05 m/s^2. We can calculate the force that the man has applied.
Work: F=M x A
1 Newton = 1 kg • m/s^2
F = 1000kg x 0.05 m/s^2
F = 50 N
The third law is directly linked with the first and second laws and is simple to understand. According to Newton’s third law of motion, every action has a similar reaction or every force has a similar opposite force. There is a large number of examples that can support Newton’s third law. For example, a rocket’s action is to push down on the ground with the force of its powerful engines, and the reaction is that the ground pushes the rocket upwards with an equal force. The changes of motion can be identified as acceleration and the rocket starts to accelerate when it is pushed down to the ground by its engines.
Newton’s three laws of motion are applied in many occasions in mechanical and medical fields. In these laws, the net force affects the motion, position and the shape of an object. These are commonly discussed forces in this matter. They are drag friction and deformation (\"Newton\'s First Law Of Motion: Examples Of The Effect Of Force\").
When there is sliding between two surfaces, a certain force is created in order to resist the movement, otherwise known as friction. In the process of friction, kinetic energy of the process is converted into heat. When an object is moving on a surface, the friction occurs, and the friction reduces the motion of the object by reducing the force which is performing the process of motion.
Drag, sometimes called air resistance, is another force which is similar to friction. Drag can exist between two fluid layers or a fluid layer and solid surface. Here, a force is acting opposite to the motion of any object moving against the surrounding fluid. Drag force always depends on velocity. Drag forces decrease fluid velocity to the solid object in its path.
Application of Newton’s Laws of Motion in the Medical Field
Newton’s laws of the motion are related to physics and are extremely useful in that of offering better health as well as fitness. According to the first law of motion, the constant velocity of a moving object is not changed unless unbalanced force is applied. The inertia is previously discussed and is used in anatomy, with the simple process of walking. When we consider the late swing stage of the gait and the particular forces moving towards the lower extremity before the strike of the heel, the muscles are not active to push extremity forward but it is on the process of moving to travel forward; this is the inertia. The body has to cope with the inertia and wants to slow down the extremity in order to get ready for heel-strike as well as, to minimize the reactionary forces which are rough. This knowledge is very useful in the process of treating the multiple issues related to the anatomy and functions of human legs and deformities in the bones which can ultimately affect the process of walking (\"Applications Of Newton\'s Laws - Boundless\").
When we consider the movement of the body, the static and dynamic movements have a certain force. In the mechanism of the human body, muscles are the objects that function and degenerate force to function the levers of the body (bones and connective tissues). It is very interesting that we can apply this formula to the motion of the human body, as well as static positions, too. In head forward static posture, the gravity and the weight (mass) of the head make a particular antero-inferior force. In order to cope this force, the human body has to contract its muscles and leverage mechanism constantly. To calculate the force that is needed to prevent the motion of the muscles from failing, one must measure the acceleration of the gravity and the weight of the head (Nuris).
When looking at the anatomy of an ankle on a human body, the ankle weight will result in an increase of the force related to the mass and downward force or pull of the gravity. In order to cope this situation, the opposite muscle has to develop a force which can overcome this particular mass. The ground reaction force concept can help one to understand this in simpler terms. When running in the soft ground, there is less impact; impact is more significant in running on concrete ground (Swanson).
Although the laws of motion are based on mechanical processes, it can be applied to the services related in the medical field. These strategies can be used in order to develop the positive impacts on the lives of people. These professionals who are associated within these industries, can use what Newton’s findings to increase their respective practices.
The second law, is concentrated on situation(s) where there is an unbalanced force of an object. According to that, the acceleration or the movement of the particular object, is based on two variables, the mass, and the net force of the object. The formula, F=MxA, which comes from this law, can be used for doctors in the Physical Therapy industry (Swanson).
Basic Biomechanics: Newton’s Laws of Motion
1) How Inertia Applies to Biomechanics
Typical everyday human body movement is mainly applied by the application of force to the ground through the feet. Force platforms allow us to record these forces, and using Newton’s laws, we can observe and test them to obtain a better understanding of the mechanical demands of different types of movement.
2) Force = Mass x Acceleration
The net force applied to a body (mass) produces a proportional acceleration. This law describes the relationship between an object’s mass, acceleration, and the applied force. Both acceleration and force must have the same vector direction. This can also be viewed in different terms such as: momentum = mass x velocity. The change of momentum of a body is proportional to the impulse impressed on the body, and happens along the straight line on which that impulse is impressed. Momentum cannot be changed unless acted upon by an outside force; it can only be conserved. Acceleration is proportional to the unbalanced forces acting on it and inversely proportional to the mass of the object (a = F/m). According to the second law of motion, the net force which is applied to the body is responsible for providing a respective propositional acceleration: F = M x A
How F=M X A Applies to Biomechanics
Mass of head and gravity combine to impose a downward force
3) Action Reaction Law
For every action, there is an equal and opposite reaction. This law describes how forces always come in pairs, meaning that anytime objects are contacting each other, they are exerting a force. An important consideration here is the concept that gravity is always touching down on every object. According to the third law, there is a reaction which is similar in capacity and opposite in the direction for any action. This law describes the nature of forces which comes in pairs an this situation can be applicable to the biomechanics.
How Action-Reaction Applies to Biomechanics
Putting an ankle weight on a patients leg will create an increase in the force of the mass and downward pull with gravity; the reaction is that the opposing muscle will have to create a force to overcome this mass. Another example of this law is with ground reaction forces. Running on soft ground will result in much less impact forces than running on hard concrete.
The laws of motion are very important as they are groundbreaking theories for the study of mechanical and engineering activities in both academic and practical aspects. These laws are related to many activities of everyday life of man and the universe. Isaac Newton was able to bring forward three very important laws of physics. Newton established the concepts of the “laws of motion” and gave them a foundation. Gravity and other forces are necessary in the process of identifying these applications that correspond with the laws of motion. There are more advantages than the academic and science fields, if researchers can one day get perfect understanding of these laws. These laws are vital for the medical field as they can use the concept to promote new tools and strategies to perform their tasks in the most efficient manner.
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