1. Forces and the Laws of Motion

2. Warm Up What are the units for:
Velocity?
Acceleration?
Force?
A car is driving on the road. How many different forces are acting on the car? What are those forces? Use a diagram to help explain.

3. Force
Force: a push or pull in a certain direction -forces can be balanced or unbalanced -unbalanced forces cause acceleration (change in motion)

4. Balanced or Unbalanced?
Do the examples below represent balanced or unbalanced forces?

5. Unbalanced forces change motion  e.g. a plane lifting off

6. Unbalanced forces change motion e.g. tailwind, headwind crosswind

7. Force continued Forces are measured in Newtons (N)
Represented by vectors
-Forces have magnitude and direction

8. Types of Forces FA = Applied Force, applied by an object or a person
Fg = Weight, the force at which a massive object attracts another towards itself, directed downward
Fn = Normal Force, a force exerted on an object on any surface ; always 90 degrees to the horizontal
Ff = Friction, exerted by the surface as an object moves across it and opposes the motion
Fair = air resistance or drag is a type of frictional force that acts on objects moving through a fluid and opposes the motion
Fbouyancy = buoyant force is a force that opposes the force of gravity in a fluid

9. Free Body Diagrams
To analyze the forces on an object, we use Free Body Diagrams

10. Free Body Diagram
Free Body Diagram: a diagram showing the forces acting on an object

11. Free Body Diagram Example
Step 1) Identify forces acting on object
Step 2) Draw a diagram of isolated object
Step 3) Draw/label vectors for all forces
Example: A box is sitting on a table. Draw a FBD

12. Free Body Diagram Example
Step 1) Identify forces acting on object
Step 2) Draw a diagram of isolated object
Step 3) Draw/label vectors for all forces
Example: A box is being pushed on a table. Draw a FBD

13. Free Body Diagram Example
Step 1) Identify forces acting on object
Step 2) Draw a diagram of isolated object
Step 3) Draw/label vectors for all forces
Example: A box is being pulled on a table. Draw a FBD

14. Free Body Diagram Example
Step 1) Identify forces acting on object
Step 2) Draw a diagram of isolated object
Step 3) Draw/label vectors for all forces
Example: A ball is falling to the ground. Draw a FBD.

15. Free Body Diagram Practice
Draw a free body diagram of a 2000 N car driving on the road. The engine gives the car 500 N of force, and friction causes 65 N of force.