Report on Newton's laws of motion

by yousefolabi (student)

| Page

Abstract

Have ever been in a car when the driver has suddenly applied the brakes? Have you ever tried to pull a heavy trolley or observed a plane flying in the air? If so, then you have experienced Sir Isaac Newton’s Laws of Motion. Newton’s three laws of motion are applied in everyday experience of our normal activities —from how the planets move around the Sun to how a person walks. This report is intended to help understand the meanings of the three laws of motion. The paper is also trying to find the relationship between force and motion. Throughout the whole report we will apply these laws to everyday practices.

Table of Contents Page number

Introduction……………………………………………………………………...3

Newton's First Law of Motion (Law of Inertia)…………………………4

Examples of the Newton’s first law of motion…………………………..4

Newton’s second law of motion…………………………………………5

Some Applications of Newton’s second law…………………………….5

Newton’s Third Law of motion………………………………………….6

Some examples of the third law…………………………………………7

Conclusions……………………………………………………………..8

References………………………………………………………………9

Introduction

Sir Isaac Newton was in my mind the father of physics. His many discoveries in the field of physics prove that. He was born in 1642 and died in 1727. He had his bachelor degree and his masters of arts by 1669. Newton’s main fields were science and mathematics. He created the well-known famous calculus before Leibniz' became popular. On the other hand, Newton's most affective and famous discovery was gravity which states that {the earth's (gravitational pull) pulls objects toward it}.

Newton came up with three laws of motion; these laws form the base of the first branch of physics (Classical Mechanics). What is unique about Newton’s laws is that they explain the way objects move and this is done by finding the relationship between force and motion on the macroscopic level. These laws are the reason behind making physics applicable almost all over the universe except for quantum mechanics, the second branch of physics, which focuses more on the motion at a microscopic level.

In this report I am going to discuss the three laws of motion and the way it deals with forces and masses and how these “factors” affect the objects’ motion.

Once we understand these laws, we will be able to answer very general questions like:

What mechanism changes the objects motion
Why do some objects accelerate? Why do some objects accelerate more than other objects?(Serway, 2004)

This report will be divided into three sections; in the first section, I will discuss Newton’s first law in details with some application. In the second part, a brief explanation ...

This is a preview of the whole essay

In this report I am going to discuss the three laws of motion and the way it deals with forces and masses and how these “factors” affect the objects’ motion.

Once we understand these laws, we will be able to answer very general questions like:

What mechanism changes the objects motion
Why do some objects accelerate? Why do some objects accelerate more than other objects?(Serway, 2004)

This report will be divided into three sections; in the first section, I will discuss Newton’s first law in details with some application. In the second part, a brief explanation will be conducted to retrieve Newton’s second law with some important real life related applications and in the third section, I will talk about Newton’s third law of motion with some real life examples.

Newton's First Law of Motion (Law of Inertia):

Newton's first law of motion states: an object at rest remains at rest and an object in motion continues in motion with a constant velocity (that is, with a constant speed in a straight line) (Serway, 2004).

This means that there is a natural trend of objects to resist any change in their state of motion and continue doing what they are originally doing. This is why the first law of motion is also called the law of inertia (NASA, n.d.)

If all the external forces cancel each other out, then the object will maintain the same state of motion (constant velocity). Now, if the velocity is zero, then the object remains at rest. Thus, if an additional external force is applied, then the velocity will change. However, how to determine the amount of change in velocity will be determined later using Newton’s second law of motion (Serway, 2004).

Now assume that someone parks a car on a flat road and forgets to put the vehicle into park. The car should stay in that spot. This state is called inertia. Imagine that All of a sudden some kid crashes into the car with a bike. These kids represent an unbalanced force. Because of this crash the car should start to move and might accelerate to 3km/h.

The result of friction between the road and tires will lead to eventual stop of the car. Therefore, the car will not be able to move further because of the friction which is defined as an unbalanced force applied against the motion. The question is what will happen when there isn’t any friction? The car would keep moving continuously without stop. Ideally this will never happen in a normal situation due to the taken for granted: friction.

Examples of the Newton’s first law of motion:

Why do we have to use car seat belts? When you are in a car then you and the car have the exact same motion, so when the driver apply the brakes, the car will stop because of the friction between the tiers and the rough street, but What will stop you? If you are not fastening your seat belt then the steering wheel or the windshield will eventually do.! (bookrags, n.d.)

While you are in the front seat of a car, assume that the driver suddenly turns left. What will happen to you? According to Newton’s first law you will continue moving in a straight line until the door in your right, turning left. What will happen inside the car is that you will slide outward and until you hit the right door (bookrags, n.d.).

Newton’s second law of motion:

According to Newton’s first law, the object will either remain at rest or continue moving in direct line with constant speed when no forces apply on it. What will happen if the amount of net force acting on an object does not equal zero? (Hewitt, 2010)

Imagine that you are doing an experiment where you apply a horizontal force on a block of ice on a smooth surface (no friction), what will happen to the block? It will move with a specific amount of acceleration. Now, if you redo the experiment but with doubling the applied force, this time, you will find that the acceleration of the block will double as well and so on. From this experiment, we end up with that the acceleration of an object is directly proportional to the applied force.

Perform the same experiment with the same conditions, but instead of changing the applied force, you change the mass of the block. After doing this experiment, you will conclude that the magnitude of the object’s acceleration is inversely proportional to its mass (Serway, 2004).

These observations discussed earlier in the experiment are summarized in Newton’s second law which states that, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (Hewitt, 2010).

Newton’s second law of motion is considered as the most important and useful law of the three, in this law Newton relates the unbalanced force acting on an object and the resultant acceleration of the same object.

This law can be put mathematically as:

∑F = ma.

Where F is the net force, m is the mass, and a the acceleration.

Some Applications of the second law:

Friction, force acting between two in contact bodies, is parallel to the surface and opposite to the direction of motion. According to Newton’s second law, an acceleration 1 m/sec/sec of a one (kg) mass requires a force of one Newton (N). However, if the friction were 4 N, a force of 5 N must be applied to give the same acceleration. The resultant force is 5N (applied) -4N (friction) which equals to 1N (bookrags, n.d.).

Rotational motion, particularly circular motion where the velocity's direction keeps changing, changing velocity means we have acceleration which is called centripetal acceleration. This centripetal acceleration requires a net force, which is acting toward the center of motion. We can observe circular motion in many enjoyment park rides like ferries wheels, and merry-go-rounds (bookrags, n.d.).

Newton’s Third Law

If you press against the corner of a table with your fingertip, the table pushes your fingertip back and makes a small dimple in your skin while keeps pushing harder, the table will do the same and a larger dent in your skin will appear. This simple experiment demonstrates Newton’s third law:

If two objects interact, the force F12 applied by object 1 on object 2 is equal in magnitude and opposite in direction to the force F21 applied by object 2 on object 1(Griffith, 2007).

In other words: F12 = - F21.

In Newton’s second law of motion, what matter is determining the acceleration of an object by knowing the value of the forces applied on It., while the third law motion interested more in a pair of forces which are equal in magnitude and opposite in direction applied on and by two different bodies (bookrags, n.d.).

Some examples of the third law:

What enables us to walk? To move forward we must push toward the back on the ground with one foot, according to Newton’s third law, the ground pushes forward, moving us ahead. After that the process kept repeating with the other foot.
How a rocket works? The rocket pushes down on the ground with the powerful engines force, as a reaction the ground pushes the rocket upwards with an equal force. Note that the two forces are equal in magnitude and applied in opposite directions (down and upwards) (Teachertech, n.d.).

Conclusions

Newton's Laws of Motion are the basic laws of classical mechanics. They are very important and have many applications. You can observe the direct influence of them everywhere. They have an effect on everyday situation of our daily lives and are involved in everything we do. The object may move without a force, but force causes changes in movement. However, bodies may move in the absence of forces as per Newton’s first law.

Once all current forces are balanced, then the behavior of bodies can be expected using Newton’s first law. On the other hand, Newton’s second law explains the behavior of objects in case of unbalanced forces.

According to Newton’s third law, (action and reaction forces) act on different bodies. Thus when we apply a certain force on an object, we will directly receive the same amount of reaction on the other object that causes the action.

You can observe one of the most important applications of the three laws of motion in a space flight. The third law provides force to move a rocket, while the second law is used to convert that force into acceleration. The first law, then, keeps a space craft for instant in orbit.

References: