What are the 3 laws of motion?

What are the 3 laws of motion?

what are the three law of motion?

Laws of motion are basic law of motion which does apply on a body when it is in motion or when it is in rest.

Isaac Newton (1642-1727)

Theory of Gravitation was represented by Newton in 1666 when he was 23 year old. After 20 year of theory of gravitation Newton published his book



"Principia mathematica philosophiae naturails" in which he described three law of motion.


These law of motion gives the reason of a body to being in motion as well as rest.

Let discuss these law of motion one by one.

 


  • First law of motion or Law of inertia-First law of motion is the other version of Law of inertia. Law of inertia originally belong to Galileo Galilei but it was written by newton in text.

    Let know first what is the Law of inertia " Inertia is very special property of substance or object by which it resist to change in its state"

    According to the first law of motion "If a object in rest it will remain in rest unless a force is not applied on it and if a object in motion it will be in motion until any external force is not applied on it to come it in rest"


 But this law does not work at earth because of on the surface of earth there is already many force exist due to which after applied a force on a object it comes in motion for a short time of period after it comes in rest.

 

 

 

 2- What is the second law of motion known as?

According to the Second law of motion  " Rate of change of momentum is equal applied force on object" 

3- Third law of motion or Action reaction- By the third law of motion " Every action have a reaction"

That mean if you applied a force on a object then the same force of magnitude will apply on you by object but in opposite direction.

Let take few example to illustrate it better

1- Rocket-
When rocket has been launched then rocket exert a thrust on surface of earth and same force apply by surface on rocket by this the pressure on down side of rocket is more than to the pressure on upper side.

2- Cannon-

When a bullet is being fired by a cannon then cannon exert a force on bullet and bullet also exert a reactive force of same magnitude but in opposite direction on cannon.


Gravitational force and Inverse square law

Gravitational force and Inverse square law


One day newton was sitting under a apple tree suddenly a apple break down from tree and falling toward the earth and by this newton got idea of gravity.Do you believe in this story maybe that is happened.
But that would not be right to say this job only done by newton.

gravity was the idea of newton but the credit of gravitation does not go to only newton there are some other character also exist behind this.

let first know about what is the gravitation.

"Gravitation is a force of attraction  which is working between two mass"

In other word " Gravity is the very special property of mass by which it attract other mass toward its centre"

Now let discuss it







what is the machenical energy ?

what is the machenical energy ?



                                     Mechanical energy                                    

Mechanical energy is the energy which uses by a body or object to do work done due to its motion and its position.
via GIPHY

In other word mechanical energy of a object is the sum of kinetic energy due to its motion and potential energy due to change in its position

Mechanical energy = kinetic energy +potential energy

  • KINETIC ENERGY- Kinetic energy is the form of energy which is responsible to being  in motion of object or body.

    Calculation of kinetic energy when a body or object is in motion-

    Suppose that a object is in rest position when a force F applied on it it made displacement S in the direction of applied force and a work is done on the object by applied force.

displacement

displacement


what is the displacement of a object?  let discuss displacement of a object.

"Shortest distance between initial and final position of a object is called displacement"

In other words "Change in position of a object with respect to time in a certain direction it is called displacement"




Now suppose that  a person standing at point A he want to go at point B now  he has two way at reach point  B

  1. He can take the way which has been seen by blue dot.
  2. Now he has one more choice to reach at point B he also take path red straight line.

Now think which path he should take to cover smallest distance to reach at point B
Your answer must be he should take red straight line path at reach point B if he take straight line path then that will be displacement and if he follow dot line path that would be distance because there are no certain direction.

NOTE- Displacement of a object could be zero.
How displacement of a object could be zero?
let discuss it 
If person start moving from his initial position at point A and he took straight line for reaching at point B and after reached at point B he return back at point A now how much displacement covered by by person?
And displacement covered by him is zero because now here at his initial position.

NOTE- Displacement is a vector quantity because it has magnitude as well as a direction it has unit m/sec