Welcome to Physics 211!

1. Welcome to Physics 211! Classical Mechanics The lecture is very full. Please move toward the center and do not leave an empty seat. Find out the following about the person you are sitting next to: 1) Their name 2) The best thing that happened to them over break.

2. Course Directors • Lectures • Mats Selen: 9am, 10am (mats@illinois.edu) • Tim Stelzer: 11am, 12pm (tstelzer@illinois.edu) • Discussion • Jim Eckstein (eckstein@illinois.edu) • Lab • Rajendra Jain (rdjain1@illinois.edu)

3. Get to know the course Home Page Everything is linked at http://online.physics.uiuc.edu/courses/phys211

4. Course Structure There are several parts, all are important: Online Prelectures (animated textbook, before lecture) Online CheckPoints (check knowledge, before lecture) Lectures – interactive, address issues found by checkpoints. Online Homework (first deadline next week) Discussion Sections (start next week) Lab Sections (start next week) smartPhysics Go to the right one ! 05

5. Course Home Page Use the Planner http://online.physics.uiuc.edu/courses/phys211

6. Planner

7. Course Home Page Get used tosmartPhysics http://online.physics.uiuc.edu/courses/phys211

8. This is where you prepare for every lecture & do your homework.

9. smartPhysics makes it easy to remembereverything related to lecture & homework CalendarView Prelecture Checkpoint Homework

10. Course Home Page Use the Gradebook http://online.physics.uiuc.edu/courses/phys211

11. Course Gradebook Go here to register your i>clicker. Prelecture, Checkpoint, Lecture, Homework, Lab and Discussion activity will be updated weekly. Prelecture, Checkpoint, & Homework scores are always up to date in smartPhysics Hovering over a grade tells you when it was last updated !!

12. It doesn’t matter which i>clicker version youhave (you can use V1 or V2 in this class) Do you have your i>clicker with you today? Clicker Question V1 V2 • Yes, and I already registered it! • Yes, and I’ll register it tonight! • No, but PLEASE give me points anyway! You will not be penalized if you don’t have a clicker today.

13. Your Grade (see Course Description) 1000 Possible Points You may miss up to 3 Prelectures, 3 Checkpoints and 3 Lectures and still get all 100 points! If you miss a Discussion Quiz, Lab, or Hour Exam due to illness, be sure to fill out an absence form, and bring documentation to 233 Loomis within a week. You can’t miss more than 3 Labs or 3 Discussions, even with an excuse.

14. Your Grade (more detail) Prelectures: 50 Preflight's: 25 Lecture participation: 25 You can miss up to 3 of each For each Homework assignment, a score is assigned out of 100% For each Quiz, a score is assigned out of 100% The lowest of the 14 Homework and 9 Quiz scores is dropped. The remaining scores are added together to give a number out of 2200. This is scaled to be worth 250 points. Bonus Points: You can earn up to 1 extra bonus point in every lecture (for a maximum of 25 bonus points for the semester) by getting the right answers to at least 5 of the clicker questions. At the end of the semester your bonus points are added to your HW/Quiz score (max 250) Your total score out of 1000 points determines your final grade.Its just a simple formula – the computer calculates it. Your grade is determined entirely by the your performance on the components of the course as described above. There is no other “extra credit” possible. A+ (950), A (920), A- (900), B+ (880), B (860), B- (835), C+ (810), C (780), C- (750), D+ (720), D (690), D- (610), and F (<610).

15. Q: What are the benefits of smartPhysics? A: You learn more What we learned in Physics 212

16. Physics 211Lecture 1 Today's Concepts: a) Displacement, Velocity, Acceleration b) 1-D Kinematics with constant acceleration If you haven't been able to do Prelecture 1 yet, you will not loseany points. Please do it as soon as you get access. 25

17. Important: We value your Checkpoint work: I would like seeing how to tell if an object is slowing down or speeding up discussed in lecture. The relationship between velocity and acceleration was a little difficult to understand. I hope that this is clarified during lecture. I suck at the ramp problem, but i have a good grasp over the derivatives and slopes stuff dealing with acceleration, velocity, and displacement. I think the ramp problem should be gone over in lecture. I thought most of it was pretty straight forward. It would be helpful if you could explain the relationships between the displacement, velocity, and acceleration graphs. I feel like the concept of acceleration in a negative velocity somewhat difficult to grasp, but thinking it logically it makes sense - I just need to get used to it. Understanding the sign of velocity in a displacement time graph. I am a little rusty with the concepts, due to the fact that I have not taken mechanical physics for 4 years now. I hope that I will understand them a lot better through this class. I found the rolling down a ramp question to be tricky. I would find it helpful to discuss problems like that in lecture. I didn't find any of the topics extremely difficult, but I would like to discuss instances where velocity and acceleration have different signs and the speeding up versus slowing down. How would you calculate the airspeed velocity of an unladen swallow

18. Prelecture Example 25

19. Prelecture Example 26

20. Displacement and Velocity in One Dimension Change in displacement Change in time 27

21. Displacement and Velocity in One Dimension Thev(t)vs.tplot is just theslope of thex(t)vs.tplot Definition: Speed = |v(t)| 28

22. Clicker Question The velocity vs. time plot of some object is shown to the right. Which diagram below could be the Displacement vs. time plot for the same object? A B C 32

23. Acceleration 33

24. Checkpoint • For the Displacement and Velocity curves shown on the left, which is the correct plot of acceleration vs. time? A B 35

25. Clicker Question Vote again A B A B Typical A answer The slope of the velocity is negative before it crosses the y axis, and positive after it crosses the y axis, that leads to a negative, then positive acceleration. Typical B answer Acceleration cannot be negative 37

26. Clicker Question • A ball is thrown straight up in the air. • Its height as a function of time x(t) is shownin the plot to the right. • Which of the following statements is true as the ball goes up? • The acceleration is positive and the ball speeds up • The acceleration is negative and the ball speeds up • The acceleration is positive and the ball slows down • The acceleration is negative and the ball slows down The concepts of slowing down, speeding up, and deceleration were a little confusing. 40

27. Your question… I was confused on question #2 of the prelecture. I understand why the acceleration was negative but I was confused to as why it was speeding up and not slowing down

28. Constant Acceleration 42

29. Checkpoint • Att = 0a ball, initially at rest, starts to roll down a ramp with constant acceleration. Suppose it moves1footbetweent = 0secandt = 1 sec. • How far does it move betweent = 1 secandt = 2 sec? • A) 1 foot B) 2 feet C) 3 feet D) 4 feet E) 6 feet 45

30. Less than half got this right so lets try again… Att = 0a ball, initially at rest, starts to roll down a ramp with constant acceleration. Suppose it moves1footbetweent = 0secandt = 1 sec. How far does it move betweent = 1 secandt = 2 sec? A) 1 foot B) 2 feet C) 3 feet D) 4 feet E) 6 feet Typical A answer Because the acceleration is constant, the ball must move the same distance as it moved between t=0 and t=1. Typical B answer since it has constant acceleration and it moves 1 ft in the first second, the 2nd second it will move twice that of the first Typical C answer the acceleration is 2ft per second squared. given t=2 the total displacement is 4ft subtract the initial displacement of 1 foot giving us 3 feet

31. Show Demo 3 1ft 4ft 9ft 16ft Att = 0a ball, initially at rest, starts to roll down a ramp with constant acceleration. Suppose it moves1footbetweent = 0secandt = 1 sec. How far does it move betweent = 1 secandt = 2 sec? A) 1 foot B) 2 feet C) 3 feet D) 4 feet E) 6 feet Typical A answer Because the acceleration is constant, the ball must move the same distance as it moved between t=0 and t=1. Typical B answer since it has constant acceleration and it moves 1 ft in the first second, the 2nd second it will move twice that of the first Typical C answer the acceleration is 2ft per second squared. given t=2 the total displacement is 4ft subtract the initial displacement of 1 foot giving us 3 feet