1. A lot of times this unbalanced external force is friction.
Newton’s First Law
“An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced external force.”
A lot of times this unbalanced external force is friction.
This means that there is a natural tendency of objects to keep on doing what they're doing.
This law is often called the “law of inertia”
Inertia – the tendency an object has to resist change in it’s motion. Objects with more mass have more inertia.
This is related to Momentum - a “quantity” of motion determined by an objects mass and velocity.
Momentum = Mass x Velocity or
p = m x v

2. Newton’s Second Law
“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).”
As the force acting upon an object is increased, the acceleration of the object is increased. As the mass of an object is increased, the acceleration of the object is decreased.
  Everyone unconsciously knows the Second Law. Everyone knows that heavier objects require more force to move the same distance as lighter objects.
However, the Second Law gives us an exact relationship between force, mass, and acceleration. It can be expressed as a mathematical equation:
FORCE = MASS times ACCELERATION
As always, if we know 2 of the variables, we can easily figure out the 3rd!

3. “For every action there is an equal and opposite reaction.”
Newton’s Third Law
“For every action there is an equal and opposite reaction.”
This means that for every force there is a reaction force that is equal in size, but opposite in direction. That is to say that whenever an object pushes another object it gets pushed back in the opposite direction equally hard.
Forces always act in pairs!
The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object.
The law of conservation of momentum says that when two or more objects interact momentum is not
gained or lost, but transferred. An exchange between the action force and the reaction force starts and stops movement. These forces are equal and opposite.

4. Match up each animation with the law it demonstrates: