laws of motion. explanation

There are 3 laws of motion. It is described(invented) by Newton.
They're:

1.First law of motion (law of inertia)

"An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force"

Explanation:

It means that a body in rest condition, will remain in rest until a force will act, whether is the Force by human, air or from anywhere.

 Example:

 A book will remain on table unless you will pick it or it is blow away by some wind. And body will remain in motion unless some force will stop it. I.e. A car will never stop until you break it.

2. Second law of motion

" Acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object."

Explanation:

It means that if a body has change in its velocity(speed) or position, then its depend upon the total force acting upon him and the mass of the body. It is also known as law of inertia. Having low mass will demand less force for change in its speed.

Example:

If you will apply same force on car and then truck. Car will have more acceleration than truck because car have less mass with respect to the truck.

Formula:

acceleration = Force/mass (a=F/m)

                                        F= a.m

Third law of motion:-

"For every action, there is an equal and opposite reaction."

Explanation:-

Its means that if there will be action from some body to other body, there is always a re-action from other body equal in force but opposite in direction.

Example:-

If you throw the tennis ball to the wall then ball will return back to you with same speed. You throw the ball it is an action the ball returns it is an reaction and in opposite direction. 

What is Physics?

First of all you have to know about  definition of physics and then break down of it.

Definition:

"The branch of science concerned with the nature and properties of matter and energy."

Physics is the branch of science which is concerned with matter and energy. It is the study of thier behaviour in different conditions and forms.
Through physics knowledge many laws has been introduced, because of it we can solve related problems easily.

What is Science?

First of all the definition of Science should be understand, then break down of every line will be good.

Definition:

"knowledge or a system of knowledge covering general truths or the operation of general laws especially as obtained and tested through scientific method."

Now explanation of it:

Means, science is a knowledge base on true things or logic. It also have some general laws which comes from experiments done by scientist. And these laws satisfies in every related problem.