PHY 113 A General Physics I 9-9:50 AM MWF Olin 101 Plan for Lecture 16: Review of Chapters 5-9

1. PHY 113 A General Physics I • 9-9:50 AM MWF Olin 101 • Plan for Lecture 16: • Review of Chapters 5-9 • Circular motion • Work & kinetic energy • Impulse and momentum PHY 113 A Fall 2012 -- Lecture 16

2. PHY 113 A Fall 2012 -- Lecture 16

3. Format of Wednesday’s exam • What to bring: • Clear, calm head • Equation sheet (turn in with exam) • Scientific calculator • Pencil or pen • (Note: labtops, cellphones, and other electronic equipment must be off or in sleep mode.) • Timing: • May begin as early as 8 AM; must end ≤ 9:50 AM • Probable exam format • 4-5 problems similar to homework and class examples; focus on Chapters 6-9 of your text. • Full credit awarded on basis of analysis steps as well as final answer PHY 113 A Fall 2012 -- Lecture 16

4. Examples of what to include on equation sheet PHY 113 A Fall 2012 -- Lecture 16

5. iclicker exercise: • Which of the following quantities are vectors: • Work • Kinetic energy • Impulse • Time • None of these • iclicker exercise: • Which of the following quantities are scalars: • Momentum • Center of mass • Force • Potential energy • None of these PHY 113 A Fall 2012 -- Lecture 16

6. Some concepts introduced in Chapters 6-9 that were not emphasized in class: • Equations of motion in the presence of air or fluid friction • So called “fictitious” forces due to accelerating reference frames • Rocket propulsion PHY 113 A Fall 2012 -- Lecture 16

7. Problem solving skills Equation Sheet Math skills • Advice: • Keep basic concepts and equations at the top of your head. • Practice problem solving and math skills • Develop an equation sheet that you can consult. PHY 113 A Fall 2012 -- Lecture 16

8. Problem solving steps • Visualize problem – labeling variables • Determine which basic physical principle(s) apply • Write down the appropriate equations using the variables defined in step 1. • Check whether you have the correct amount of information to solve the problem (same number of knowns and unknowns). • Solve the equations. • Check whether your answer makes sense (units, order of magnitude, etc.). PHY 113 A Fall 2012 -- Lecture 16

9. Review of some concepts: Newton’s second law for the case of uniform circular motion r PHY 113 A Fall 2012 -- Lecture 16

10. Example: Suppose a race car driver maintains of speed of v=40m/s around a horizontal level circular track of radius r=100m. Assuming that static friction keeps the car on the circular path, what must be the minimum coefficient of static friction for the car-road surface? r PHY 113 A Fall 2012 -- Lecture 16

11. Definition of vector “dot” product q PHY 113 A Fall 2012 -- Lecture 16

12. Definition of work: F dr ri rj PHY 113 A Fall 2012 -- Lecture 16

13. Example: PHY 113 A Fall 2012 -- Lecture 16

14. Introduction of the notion of Kinetic energy Some more details: Consider Newton’s second law: Ftotal = m a  Ftotal · dr= m a ·dr Wtotal= ½ m vf2 -½ m vi2 =Kf-Ki Kinetic energy (joules) PHY 113 A Fall 2012 -- Lecture 16

15. Special case of “conservative” forces conservative  non-dissipative PHY 113 A Fall 2012 -- Lecture 16

16. Special case of “conservative” forces conservative  non-dissipative PHY 113 A Fall 2012 -- Lecture 16

17. PHY 113 A Fall 2012 -- Lecture 16

18. Example: PHY 113 A Fall 2012 -- Lecture 16

19. Summary of physics “laws” PHY 113 A Fall 2012 -- Lecture 16

20. Another example; now with friction T f Mass m1 (=0.2kg) slides horizontally on a table with kinetic friction mk=0.5 and is initially at rest. What is its velocity when it moves a distance Dx=0.1m (and m2 (=0.3kg) falls Dy=0.1m)? T m2 g 0 PHY 113 A Fall 2012 -- Lecture 16

21. PHY 113 A Fall 2012 -- Lecture 16

22. Relationship between Newton’s second law and linear momentum for a single particle: PHY 113 A Fall 2012 -- Lecture 16

23. Physics of composite systems PHY 113 A Fall 2012 -- Lecture 16

24. PHY 113 A Fall 2012 -- Lecture 16

25. Finding the center of mass PHY 113 A Fall 2012 -- Lecture 16

26. Examples of two-dimensional collision; balls moving on a frictionless surface PHY 113 A Fall 2012 -- Lecture 16

27. Examples of two-dimensional collision; balls moving on a frictionless surface PHY 113 A Fall 2012 -- Lecture 16

28. Example: two-dimensional totally inelastic collision m1=1500kg m2=2500kg PHY 113 A Fall 2012 -- Lecture 16

29. Energy analysis of a simple nuclear reaction : Q=4.87 MeV PHY 113 A Fall 2012 -- Lecture 16

30. Energy analysis of a simple reaction : Q=4.87 MeV PHY 113 A Fall 2012 -- Lecture 16