1. Physics 11 Advanced Mr. Jean March 20 th, 2012

2. The plan: Video clip of the day Newton’s 2 nd Law Newton’s 3 rd Law Free Body Diagrams

3. Newton’s First Law: Inertia Car Demonstration #1

4. Newton’s Second Law: Demonstration #2: –Heavy car vs. Light Car –Constant Elastic Potential

5. Newton’s Third Law: The mutual reaction of any two bodies are equal and opposite.

6. Demonstration #3: Heavy car vs. Light car –Elastic is stretched between the two cars –What will happen if the same force is applied to both vehicles?

7. Julius Sumner Miller Newton’s Third Law

9. Free Body Diagrams: VERY IMPORTANT: Free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. These diagrams will be used throughout our study of physics.

10. Free Body Diagrams (FBD): There will be cases in which the number of forces depicted by a free-body diagram will be one, two, or three. Diagrams are to depict all the forces that exist for that object in the given situation.

11. Examples of FBD:

12. 1) Start with the object of interest. –Place a rectangle at the center of your page to represent this object. 2) Lay out all forces being experienced by the object. –Draw neat straight lines representing the forces. 3) List variables on the right hand side so people reading your diagrams know what you are talking about. Key pieces to a FBD

13. Free Body Diagrams: http://www.brightstorm.com/science/physic s/newtons-laws-of-motion/free-body-force- diagrams/http://www.brightstorm.com/science/physic s/newtons-laws-of-motion/free-body-force- diagrams/ Note: There is no different between arrows above or below the object of interest.

14. FBD – Try this one: A car is traveling on a level surface heading east and it begins to slow down.

15. Normal Force: The normal force is the component, perpendicular to the surface of contact. Example: the surface of a floor is preventing the object from penetrating the surface. The floor supplies the normal force.

16. Surface Friction: The magnitude of the force of surface friction is the product of the coefficient of friction and the magnitude of the normal force. The direction of the force of friction is always opposite to the direction of the motion.

19. Frictional Forces: Example #1: An 80kg student is dragged across the floor. The coefficient of friction between the floor and the student is 0.3. A) Draw a force diagram representing this situation.

20. Frictional Forces: Example #1: An 80kg student is dragged across the floor. The coefficient of friction between the floor and the student is 0.3. A) Draw a force diagram representing this situation.

21. Frictional Forces: Example Question: An 80kg student is dragged across the floor. The coefficient of friction between the floor and the student is 0.3. Calculate the following: B) What is the force of friction?

22. Frictional Forces: An 80kg student is dragged across the floor. The coefficient of friction between the floor and the student is 0.3. Calculate the following: C) What force is required to move the student?

23. Frictional Forces: An 80kg student is dragged across the floor. The coefficient of friction between the floor and the student is 0.3. Calculate the following: D) What is the students acceleration if 300N of force are applied to them?

25. Frictional Forces: Example #2: The force of friction experience by an object is 255N. The object has a weight of 300N. 1) What is the coefficient of friction? 2) What is the objects acceleration if 500N of force are applied to the object?

28. Situation:

29. Questions: Using the image of Wile E. Coyote, determine the following values. 1) What is the coefficient of friction? 2) What is the mass of the rocket & Wile E.? 3) What is the acceleration of Wile E.?