1. Introduction to Forces
Textbook: 4.3, 4.4
Homework: WS.

2. Forces A force is a push or a pull Ex. Gravity, Tension, Lift, etc…
A vector quantity
Given the symbol F
Units = 1 kg m/s2 = 1 N
Ex. Gravity, Tension, Lift, etc…
The four fundamental forces are: gravity, electromagnetic, strong and weak nuclear force

3. Free Body Diagrams (FBDs)
A quick sketch showing all the forces acting on an object
Add up all the forces as vectors to determine the total, or net Force (Fnet)
Fnet equals the sum of all forces
Ex. Draw a FBD of a car speeding up
Ex. Draw a FBD of a plane taking off from a runway
Ex. Draw a FBD of a skateboarder coasting to a stop
Ex. Draw a FBD of an apple hanging from a tree
Ex. Draw a FBD of a ball falling with no air resistance
Ex. Draw a FBD of a person falling at their terminal velocity

4. Name of forces Fg = force of gravity Fa = applied force
Fk = force of kinetic friction
T = force of tension
FN = normal force

5. Drawing FBDs Ex 1. Draw a FBD of an apple hanging from a tree
Ex 2. Draw a FBD of a skateboarder coasting to a stop
Ex 3. Draw a FBD of a plane taking off from a runway
Ex 4. Draw a FBD of a car speeding up

6. Newton’s First Law (Inertia)
An object at rest, remains at rest; an object in motion, remains in motion; unless acted upon by an unbalanced force.
Ex. Talk about car accidents
Ex. Buses making turns