1. Warm UP
What is the difference between mass and weight?

2. The cause of forces
A force is an action that has the ability to change motion. It is a push or pull
Forces can increase or decrease the speed of a moving object.
Forces can also change the direction in which an object is moving.

3. All forces in the universe come from only four basic forces.
Four Elemental Forces
All forces in the universe come from only four basic forces.

4. Unit of force The newton (N) is a metric unit of force.
1 newton (N) equals lbs.
If one pound of force equals newtons, then a 100 lb person weighs newtons

5. Strong Nuclear Force This force holds the nucleus of an atom together.
This is a very strong force but only reaches a short distance.

6. Electromagnetic force
The electromagnetic force acts between charged particles – protons and neutrons - and is the combination of all electrical and magnetic forces.
This force holds atoms together in molecules.

7. WEAK force
The weak force is stronger than gravity, but it is only effective at very short distances.
Causes Radioactive Decay
Only occurs at a subatomic level

8. Gravity The force of gravity on an object is called weight.
At Earth’s surface, gravity exerts a force of 9.8 N on every kilogram of mass.

9. Weight vs. mass Weight and mass are not the same.
Mass is measured in kilograms (kg).
Weight is a force measured in newtons (N).
Weight depends on mass and gravity.

10. Contact forces
Contact force. ... Pushing a car up a hill or kicking a ball or pushing a desk across a room are some of the everyday examples where contact forces are at work. 
Examples of contact forces are applied, gravitational, normal and frictional

11. Applied Force
An applied force is a force that is applied to an object by a person or another object.
A person is pushing a desk across the room, is applying a force upon the object. The applied force is the force exerted on the desk by the person.

12. gravitational
The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface.

13. Normal force
The normal force is the support force exert ed upon an object that is in contact with another stable object.
For example, if a book is resting upon a surface, then the surface is exerting an upward force upon the book in order to support the weight of the book.

14. Frictional force
Frictional Force refers to the force generated by two surfaces that contact and slide against each other.