Welcome to Physics 211 !
Classical Mechanics
The lecture is not all that full. Please move toward the center
and sit together. (We will be doing some among student
discussion so this is important.)
Talk to the person sitting next to you and find out their name and the best
thing that happened to them over the break.
Mechanics Lecture 1,
Course Personel
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Lectures
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Discussion
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Prof. Rebecca Rosenblatt: 1:30pm - 2:20pm M T W R
(rrosenbl@illinois.edu)
Vastal Dwivedi: 8am - 10am T R
(vdwived2@illinois.edu)
Mark Schubel: 10am- 12pm T R
(schubel2@illinois.edu)
Lab
Jason Merritt: 8am - 10am M W
(jmerrtt2@illinois.edu)
 Robert Chamberlain: 10am – 12pm M W
(rchambe2@illinois.edu)
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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 this week)
Discussion Sections
Go to the right one !
Lab Sections
05
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http://courses.physics.illinois.edu/phys211/
Course Home Page
Use the
Syllabus link
http://courses.physics.illinois.edu/phys211/
Syllabus…
Lecture slides are available here
after every lecture
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http://courses.physics.illinois.edu/phys211/
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Mechanics Lecture 1,
smartPhysics makes it easy to remember
everything related to lecture & homework
Calendar
View
Prelecture 2
Homework 1 & 2
Prelecture 1
Checkpoint 1
Checkpoint 2
Course Home Page
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http://courses.physics.illinois.edu/phys211/
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Lecture, Homework, Lab
and Discussion activity
will be updated weekly.
Prelecture, Checkpoint, &
Homework scores are always up
to date in smartPhysics
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.
Voting for someone else violates U of I academic integrity rules!
V2
Your Grade (see Course Description)
Prelectures + Checkpoints + Lectures
100
Labs (9)
150
Quizzes (9)
100
Homework (26)
150
Hour exams (3 x 100 each)
300
Final Exam
200
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 so far
Prelectures + Checkpoints + Lectures
100
Labs (9)
150
Quizzes (9)
100
Homework (26)
150
Hour exams (3 x 100 each)
300
Final Exam
200
Prelectures:
50
Preflight's:
25
Lecture participation: 25
You can miss up to 3 of each
The lowest Quiz is dropped and
the lowest Homework is dropped
To get lecture participation credit you need to vote on at least half of the questions in a lecture.
(i.e. it is possible to get part of a bonus point but no participation point for a lecture)
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 Quiz scores (max 100)
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
20
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%
Q: How do I get help ? A: Office Hours
HW Deadline
We can’t answer
your physics
questions via email.
It is not a good way
to communicate
physics.
Note: There is a 2nd HW deadline for 80% credit (usually a
week after the first – check your smartPhysics calendar)
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.
25
Important: We value your Checkpoint work:
• It says the deadline to this question is June 10th at 8am,
but the lecture is on the 10th at a later time.
• I would like it if more problems were discussed in class and
how to tell when to use the different equations.
• slowing up and slowing down combined with acceleration
• Constant acceleration
• Can we discuss the second checkpoint?
Prelecture Example
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Prelecture Example
26
Displacement and Velocity in One Dimension
Change in displacement
Change in time
I do not like the use of the word displacement. I was taught, and I still believe,
that the displacement is the change in the distance and object travels.
27
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
32
Acceleration
33
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
Typical A answer
The acceleration is the derivative of the velocity so the velocity is
decreasing and then increasing therefore the acceleration is negative
and then positive.
Typical B answer
Because the velocity is never negative, the acceleration should
never be negative.
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
How do you look at a graph and understand if an object is
speeding up or slowing down?
40
Your question…
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
Some got this wrong 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
Since the acceleration is constant, then we can say the ball has a velocity
of 1m/s, so in another second the ball traveled another foot.
Typical B answer
Since its constant acceleration the distance will double
Typical C answer
a=2 from displacement formula. When time is 2 seconds, displacement is 4 foot, so
from t=1 and t=2, it moved 3 foot.
I would like to see the explicit way
of applying the formulas in order to
get the answer to the rolling down
the ramp problem.
16ft
0
0
3
4ft
9ft
1ft
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
Since the acceleration is constant, then we can say the ball has a velocity
of 1m/s, so in another second the ball traveled another foot.
Typical B answer
Since its constant acceleration the distance will double
Typical C answer
a=2 from displacement formula. When time is 2 seconds, displacement is 4 foot, so
from t=1 and t=2, it moved 3 foot.