# NEWTON'S LAWS OF MOTION AND THEIR APPLICATION

** SIR ISSAC NEWTON **was a physicist who studied much about motion and came up with three practical laws. These laws are now known as Newton's laws of motion. This law defines the relative motion of objects in terms of the distance they cover, the time they use in covering the distance in question, the velocity involved and the force of gravity or any other acceleration. To the layman, most of this scientific concepts are only theories that don't have their ways in real life. This write-up will break the concept in question into the simplest form that you can relate. For better understanding, we have to understand some basic terms use in the expressi0n of these law.

**1**. **Displacement(s)**; This term is used to relate to the distance between two points in a specific direction. For example, the distance between points **A **and **B **on a map is 50km and **B **lies north of **A**. Spread also has the same definition but does not consider the direction.

**2. Velocity(v)**; This is the displacement of an object within a specific time. You walk 10 km in 300 seconds , your velocity is your displacement over the time it took you.

3. **Acceleration (a)**; It is the time rate of change of velocity. That is the velocity over the time it occurs. Acceleration due to gravity (g) is a special type of acceleration that acts on objects high above the ground. These are the basic terms in the law. Haven't gain much ground, lets digest the issues of thee laws.

**NEWTON'S FIRST LAW (THE LAW OF INERTIA)**

The law of inertia states that, a body will continue to be at least or uniform motion in a straight line unless it is acted on by an external force to change its state. This law is telling us that when an object is at rest, it will continue to be there unless someone or something applies an external force to it. If not it will continue to stay still. Also, when a body says a car is moving it will want to continue moving unless an external force causes it to stop or change its direction. From the two scenarios, we can say that the object in question is feeling lazy to move or stop when it is already moving. This reluctance of an object to change its state of motion is what is termed **INERTIA**.

There is a lot of examples of this law, here are few of them:

1. When a stationary car wants to move, it can not do that on its own. It is feeling lazy to move, but when you push it or start the engine it will move because an external force is in operation.

2. When a car is moving, it will continue to move unless the breaks are applied or something comes as a hindrance to its motion.

3. When a car is moving and the driver wants to negotiate a curve it has to control the steer which generates a force to change the direction of the car.

**NEWTON'S SECOND LAW**

**Newton's second law **states that the rate of change of linear momentum of a body is directly proportional to the force applied and takes place in the direction of the force. **MOMENTUM **is simply the product of the mass and the velocity. It is obtained by simply multiplying the mass of a body and its velocity. For instance, an object has an initial velocity of u and that is changed to final velocity v as its motion proceed, mostly the mass does not change. The second law is telling us that the rate of velocity with time is mathematical given as **v-u/t**. Then change of momentum is given as mv-mv which is directly proportional to the force applied. **F**= **m**(**v-u**)/**t**, but acceleration a is the time rate change of velocity, **v-u**/**t**=**a**. Then **F=ma**. Where F is the force, m is the mass and a is the acceleration with which the body moves.

Applications of Newton's second laws in our daily lives.

With momentum, force is not only a mass dependent quantity. A body can have a small mass but may produce small momentum. While a small body with a high velocity will produce a high momentum hence much force is produced. This explains why a big vehicle will be badly damaged after colliding. Also, a bullet with a very high velocity can be used to stop a moving truck. The above situation can only happen when the bullet is travelling with a very high velocity such that the product of the mass and velocity of the bullet ( momentum of the bullet) is equipped you the product of mass to the velocity of the truck ( momentum of the truck.) . With all these examples there should be no externa force unless those in question.

### NEWTON'S THIRD LAW

The concept of Newton's third law is applied in all aspects of human life. It is applied in economics, accounting, and even religion not to talk of the sciences. This states that, to every action, there is an equal and opposite reaction. Or action and reaction are equal but opposite. According to this law, whenever an action is performed, force is applied. The dower of the action receives a recoil force which is equal in magnitude to the force used in the acting. This law can be closely related to the saying that that whatever goes up must come down. Mathematically F=-F where F is the force applied in acting and the minus sign is to indicate that the second force is in opposite directions to the first one.

This law is applied in almost all aspects of life. This explains why fishermen paddle the bolt backwards while it moves forward. The force that is generated when you paddle backwards, is the same force that is used in moving the bolt forward but these two forces are in the opposite direction. Also, when a moving vehicle collides with a stationary vehicle the two damage even though one is not moving. This is because the force that the moving vehicle use in a collision is the same recoil that it will receive in the opposite direction.

### CONCLUSION

These laws are not complicated as we thought. Newton observed the everyday motion activities and summarised them into a few laws and equations. The law of inertia explains how lazy an object feels to move when at rest or stop when it is already moving. The second law explains how change of momentum is direct to the force applied. The third law is on the impact one receives when action occurs.

Reference

1. Nasa: https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/newtons-laws-of-motion/

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