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.
Mechanics
Lecture 1,
Course Directors
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Lectures
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Discussion
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Mats Selen: 9am, 10am (mats@illinois.edu)
Tim Stelzer: 11am, 12pm (tstelzer@illinois.edu)
Jim Eckstein (eckstein@illinois.edu)
Lab
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Rajendra Jain (rdjain1@illinois.edu)
Get to know the course Home Page
Everything is linked at
http://online.physics.uiuc.edu/courses/phys211
Course Structure
smartPhysics
There are several parts, all are important:
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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)
Go to the right one !
Lab Sections (start next week)
05
Course Home Page
Use the
Planner
http://online.physics.uiuc.edu/courses/phys211
Planner
Course Home Page
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smartPhysics
http://online.physics.uiuc.edu/courses/phys211
This is where you prepare for every lecture & do your homework.
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everything related to lecture & homework
Calendar
View
Prelecture
Checkpoint
Homework
Course Home Page
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Gradebook
http://online.physics.uiuc.edu/courses/phys211
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 !!
Clicker Question
It doesn’t matter which i>clicker version you
have (you can use V1 or V2 in this class)
Do you have your i>clicker with you today?
V1
A) Yes, and I already registered it!
B) Yes, and I’ll register it tonight!
C) No, but PLEASE give me points anyway!
You will not be penalized if you don’t have a clicker today.
V2
Your Grade (see Course Description)
Prelectures + Checkpoints + Lectures
100
Labs
150
Hour exams (3 x 100 each)
300
Final Exam
200
Homework (14) + Quizzes (9)
250
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.
Your Grade (more detail)
Prelectures + Checkpoints + Lectures
100
Labs
150
Hour exams (3 x 100 each)
300
Final Exam
200
Homework (14) + Quizzes (9)
250
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).
Q: What are the benefits of smartPhysics?
A: You learn more
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Viewer
Non-Viewer
25
What we learned in Physics 212
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15
10
5
0
43
48
52
57
61
65
70
74
78
83
87
91
96
100
Exam Score
Students who…
Exam 1 average
Viewed pre-lectures
80%
Blew through pre-lectures
73%
Physics 211
Lecture 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 lose
any points. Please do it as soon as you get access.
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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
Prelecture Example
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Prelecture Example
26
Displacement and Velocity in One Dimension
Change in displacement
Change in time
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Displacement and Velocity in One Dimension
The v(t) vs. t plot is just the
slope of the x(t) vs. t plot
Definition:
Speed = |v(t)|
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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
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Acceleration
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Checkpoint
For the Displacement and Velocity curves shown on the
left, which is the correct plot of acceleration vs. time?
A
B
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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
Clicker Question
A ball is thrown straight up in the air.
Its height as a function of time x(t) is
shown in the plot to the right.
Which of the following statements is true
as the ball goes up?
A)
B)
C)
D)
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.
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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
Mechanics Lecture 1,
Constant Acceleration
42
Checkpoint
At t = 0 a ball, initially at rest, starts to roll down a ramp with
constant acceleration. Suppose it moves 1 foot between
t = 0 sec and t = 1 sec.
How far does it move between t = 1 sec and t = 2 sec?
A) 1 foot B) 2 feet C) 3 feet D) 4 feet E) 6 feet
45
Less than half got this right so lets try again…
At t = 0 a ball, initially at rest, starts to roll down a ramp with
constant acceleration. Suppose it moves 1 foot between
t = 0 sec and t = 1 sec.
How far does it move between t = 1 sec and t = 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
Show Demo
At t = 0 a ball, initially at rest, starts to roll down a ramp with
constant acceleration. Suppose it moves 1 foot between
t = 0 sec and t = 1 sec.
3
4ft
1ft
9ft
16ft
How far does it move between t = 1 sec and t = 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