Newtons Laws

Newtons Laws are three important statements which define the way in which objects and forces interact with each other.
Here we will define the laws and present some real world analogies.

The Laws

First Law

A body at rest will remain at rest, and a body in motion will remain in motion unless acted upon by an external force.
What this really means.
If we push on an object with sufficient force it will accelerate.
It will accelerate in the direction we push it.

Second Law

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
What this means
If you push twice as hard it accelerates twice as fast.
If its mass is doubled, it will accelerate half as quickly.
Related Equations
F=ma
F
Force [kg m s-2] or N
m
Mass [kg]
a
Acceleration [m s-2]

Third Law

Every action has an equal and opposite reaction.
What this means
If you push an object it pushes you back. We tend take this for granted as we are used to interacting with the physical world every day.
An example of this is pushing a broken down car, if you push the car with a force of 100N the car pushes back on you with an equal force of 100N.

Web references