Newtons 3 Laws of Motion
An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force
Inertia is the law that says an object will stay in motion until some sort of force stops it.
My picture above shows a car running down the road until a surface / wall stops it and blocks the way. The car would have continued to move until another force stopped it.
Example: a toy car riding until friction, wall, gravity ect. stops it.
For every action there is an equal and opposite re-action.
The picture above shows Newtons Cradle showing the every action has an opposite and equal reaction. The balls energy passes through the others to the end and the energy goes back through again.
Action and Reaction is when you put force on an object and the object is applying the same amount of force back to you, but which ever object has less mass is the one that moves.
Example: pushing against the wall and not being able to move it
Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).
Acceleration is when something speeds up or slows down, so basically when the velocity changes.
The picture above shows a car speeding up. and a car turns eventually. When an object changes speed and direction, its changing velocity.
Example: a toy car going straight and then something persuading it to change velocity.