1. Free Body Diagrams by: Heather Britton

2. Free Body Diagrams When analyzing forces a free body diagram should be drawn A free body diagram shows the magnitude and direction of all forces acting on an object

3. Free Body Diagrams How to draw a free body diagram when an object is on an incline 1. Draw your incline and label θ 2. Draw your object

4. Free Body Diagrams 3. Draw an arrow through the center of your object at a right angle to the incline. Label the arrow above the incline F N and the arrow below the incline F perpendicular

5. Free Body Diagrams 4. Draw another arrow perpendicular to the first arrow at the base of the object and label in F parallel and F f 5. Draw another arrow starting at the intersection of the first arrow and the incline straight down. Label this arrow F g

6. Free Body Diagrams Label θ between arrows F g and F perpendicular F g = mg F N = F perpendicular F perpendicular = cos(θ)F g F parallel = sin(θ)F g

7. Free Body Diagrams Example 1 A trunk weighing 562 N is resting on a plane inclined at 30° from the horizontal. Find F parallel and F perpendicular to the plane

8. Free Body Diagrams Example 1 (cont.) If the inclined plane is frictionless what is the trunk’s acceleration?

9. Free Body Diagrams Example 1 (cont.) If the coefficient of kinetic friction is 0.2 what will the trunk’s acceleration be?

10. Free Body Diagrams Example 2 A coin placed on the cover of a book just begins to move when the cover makes an angle of 38° with the horizontal. What is the coefficient of static friction between the coin and the cover?