PH 211 Winter 2014

1. PH 211 Winter 2014 Monday January 13

2. Google moderator Which topic would you like to discuss in class on Wednesday? https://www.google.com/moderator/#15/e=20e0eb&t=20e0eb.40

3. Google moderator Todays questions: http://www.google.com/moderator/#15/e=20ca00&t=20ca00.40

4. Chapters 1-4 - Kinematics: describing motion • Multiple representations for describing motion (words, motion diagrams, graphs, equations), including using qualitative representations to make predictions about tricky problems, AND using them to move to your quantitative representation • Solving for the motion of an object with multiple ‘stages’ of acceleration • Solving for relational motion between two objects (such as finding where they will collide) • Solving motion in 2-dimensions (such as projectiles) • Building up use of problem solving rubrics, justifying answers, understanding models and assumptions 2nd‘third’ is Newton’s laws’, last ‘third’ is conservation laws

5. 1 7 2 6 3 5 4 Which of the following statements is true? The acceleration changes from positive to negative. The magnitude of the velocity is constant. At any given time the acceleration and velocity have the same sign. The acceleration is never zero.

6. Which statement is true • The acceleration changes from positive to negative. • The magnitude of the velocity is constant. • At any given time the acceleration and velocity have the same sign. • The acceleration is never zero. 1 7 2 6 3 5 4 148 of 215 :01

7. 1 7 2 6 3 5 4

8. Use a motion diagram to answer the following question: You throw a ball straight up in the air. At the highest point, the ball’s • velocity and acceleration are zero. • velocity is nonzero but its acceleration is zero. • acceleration is nonzero, but its velocity is zero. • velocity and acceleration are both nonzero.

9. Use a motion diagram to answer the following question: You throw a ball straight up in the air. At the highest point, the ball’s • velocity and acceleration are zero. • velocity is nonzero but its acceleration is zero. • acceleration is nonzero, but its velocity is zero. • velocity and acceleration are both nonzero. 162 of 215 :01

10. http://www.youtube.com/watch?v=5C5_dOEyAfk

11. Problem solving rubric • What is a model? • How do models incorporate assumptions and simplifications? • Which models/assumptions/simplifications are we using today? • (consider the video – what assumption(s) allow us to say they fall at the same rate?)

12. Draw a representation for the following: What constant acceleration does a rocket need to reach a speed of 200 m/s at a height of 1.0 km?

13. Translating motion diagrams to graphs • Generate x vs. t, v vs. t and a vs. t graphs

14. x t A B C D E

15. Where is the velocity zero? • A • B • C • D • E 166 of 215 :01

16. Where is the acceleration zero? • A • B • C • D • E 164 of 215 :01

17. Practice: draw v(t) and a(t) for this graph x t A B C D E