# Newton's Laws

## Newton's Laws

Newtons law describes the body's motion in terms of physics .It has been widely accepted by the science community for the past century, in total there are three laws that affect the laws of motion. This indicates that the projectile is moving.

## Newton's First Law

His first law of motion is called the law of inertia, his law is;

A body remains at rest or in uniform motion until and unless an external force acts upon it (Unbalanced force).


The basis of this law means that if an object is not moving it will only move when a force is applied onto it, as well as an object that is in motion will not change its velocity (accelerate) until a net force acts upon.

## Newton's Second Law

His second law is more notably named as the law of acceleration. His law is;

The rate of change of momentum of an object is proportional to the resultant force acting on the body and is in the same direction.


This law means that the force of the object moving will be equal to the opposing force such as air resistance. Mathematically, Newton's second law is stated as:

${\displaystyle {\overrightarrow {\mathbf {F} }}={\frac {d{\overrightarrow {\mathbf {p} }}}{dt}}}$


where F is the total force, p is the momentum, and t is the time passed. In classical physics, where the object's mass is constant, this equation becomes a more familiar form:

${\displaystyle {\overrightarrow {\mathbf {F} }}={\frac {d{\overrightarrow {\mathbf {p} }}}{dt}}={\frac {dm{\overrightarrow {\mathbf {v} }}}{dt}}=m{\frac {d{\overrightarrow {\mathbf {v} }}}{dt}}=m{\overrightarrow {\mathbf {a} }}}$


where m is the object's mass and a is the acceleration of the object.

Example

A skydiver jumps from a plane and accelerates until he reaches the highest velocity possible, when this happens his acceleration is equal to nothing, this happens when air resistance is equal to the downward force of the skydiver.

## Newton's Third Law of motion

Newtons third and final law is the law of Interaction in which he Doubted;

All forces occur in pairs, and these two forces are equal in attitude and opposite in direction.


It can be said that "every action has opposite and equivalent reaction

${\displaystyle F_{-}=-F}$

Examples
1. When we push a wall, it creates an opposite amount of force, thus, either we move or does the wall move.

This in simple terms is that to every action force there is an equal, but still the same, reaction force. For example if one presses on a wall an equal, and same force, is pushed back at them.

## Newton's Fourth Law

At equilibrium, the sum of all forces (the net force) act on matter mut be zero

Example

For a system that experiences 2 forces Interaction Force and Opposition Force

${\displaystyle F+F_{-}=0}$

## Newton's Fifth Law

The attraction force between two mass is indirectly proportional to the separation distance squared
${\displaystyle F}$ ~ ${\displaystyle {\frac {1}{r^{2}}}}$

Example

Gravitational force of free fall body

${\displaystyle F_{g}=G{\frac {mM}{r^{2}}}}$

Coulomb force o

${\displaystyle F_{q}=K{\frac {qQ}{r^{2}}}}$