2. Inertia, intro to vectors, FBD Wednesday, September 7, 2016

3. Unit 2: Static Forces Wednesday, 9/7  Respond to the following on your warm-up sheet:  What is acceleration?  What causes an object to accelerate?  Update your planner with the important dates below Upcoming important dates  Friday, 9/9 – homework quiz  Tuesday, 9/13 – homework quiz  Tuesday, 9/13 – last day to re-quiz over the summer assignment  Thursday, 9/15 – unit quiz  Monday, 9/19 – unit test

4. Simulating Inertia  Flick the index card fast and record what happens to the penny.  Roll the glue stick towards the meter sticks and record what happens to the glue stick. Record your observations.

5. Inertia  Video guide questions  Give an example of an object (football player) resisting change.  What caused the object (football player)to change their motion?  What is the most important factor effecting a players ability to resist change?

6. Objects tend to stay at rest OR objects tend to stay in motion at a constant speed.

7. Matter  Takes up space  Atomic level; protons, neutrons, and electrons.

8. Objects  Collection of particles  The interactions of the particles are not important.  Example; football player (scoring a touch down, homeostasis).  Objects are treated as if they have no internal structures.

9. Properties of Objects  We will consider different properties of objects throughout our Physics journey.  For this unit we will focus on inertial mass. Inertial mass – causes objects to resist changes in motion; Measured In kilograms (kg); symbol - m

10. Systems  A collection of objects which interact with each other Source: http://www.newyorker.com/hum or/daily-shouts/if-i-were-a- ballerina Source: http://thesurge.com/stories/the-physics-of-car-crashes https://www.engadget.com/2015/09/13/solar-system-simulation-music/

11. Systems  Are collections of objects interacting with one another.  The properties of a system are determined by the properties of the objects and their arrangement (ex: consider the images from the previous slide).  The observer determines which objects will be considered when analyzing a system (key component of analyzing AP Physics level questions)

12. Review: Vector v. Scalar Quantities Vector Quantity Fully described by both magnitude (number plus units) AND direction Represented by arrows -displacement -velocity -acceleration -force Scalar Quantity Fully described by magnitude alone -distance -mass -temperature -time -speed -electrical charge

13. Vector Video https://www.youtube.com/watch?v=A05n3 2Bl0aY

14. Vector example The bowling ball moved 20 meters north from the point of reference. Δx = 20 m North Direction Magnitude, scalar

15. Forces  A Force is the action that occurs when objects interact with one another.  Categories of forces  Push  Pull  Think back to the football video; were there any pushes or pulls happening?  Forces can change an objec’ts motion.  Forces are vectors (magnitude and direction)  Measured in Newtons (N) 1 N = Kg * m s 2

16. Common Forces  Familiarize yourself with the forces on the back of your handout.

17. Free body diagram (FBD)  Pictorial representation of forces acting on an object.

18. Free body diagram steps 1. Replace the object with a dot or box. 2. Identify the force pairs acting on the object 3. Identify contact forces acting on the object. Remember that only something that is physically touching the object can apply a contact force Possible types of contact forces – push, tension, normal, and friction 4. Add arrows force and label the forces 5. Add any force values that are known

19. FBD Example - static A block is sitting on a table.

20. FBD Example – constant velocity A block is being moved across a table.

21. Drawing FBD practice – 10 minutes

22. Net force equation

23. Net Force Example - static A block is sitting on a table.

24. Net Force Example – constant velocity A block is being moved across a table.

25. Weight vs. Mass  Mass is matter (atomic level)  Weight is the force of gravity acting on mass.  Weight is represented by the symbol F g  F g will always act on an object.

26. How to Calculate force of gravity (weight) Acceleration of gravity. On earth it is 9.8 m/s 2. We Simplify and use 10.0 m/s 2 Mass of the object, measured In kilograms (kg) Weight (force of gravity), measured in Newtons (N)

27. Example – calculating weight (F g ), 1.A 1.5 kg block is sitting on a table

28. Example – calculating weight (F g ) 1.A 1.5 kg block is moving across the table a a constant velocity on a table

29. Homework  Review your notes and practice from today.  Write net force equations for four (4) of the free-body diagrams you drew in class today (you can choose whichever ones you want).  Complete the weight (F g ) calculation practice.  Review, mark, and summarize vector notes.

30. Cool Down  Create a college pennant for your dream college.  Can you do all of the ‘I can statements’? If no what actions are you going to take to make sure you can?