Mechanics Lecture 1, Mechanics Lecture 1, Slide Slide 11
Welcome to Physics 211!Classical Mechanics
F mar r
Course Home Page
Course Home Pagehttp://online.physics.uiuc.edu/courses/phys211/summer12/http://online.physics.uiuc.edu/courses/phys211/summer12/
Course Directors
Lecture Doug Davis ([email protected]) also ([email protected]) http://ux1.eiu.edu/~addavis/DrD/Welcome.html
Discussion Robert Chamberlain ([email protected])
Laboratory Bo Han ([email protected]) Jason Merritt ([email protected])
Course meetings
Mechanics Lecture 1, Slide 5
The best way to predict the futureThe best way to predict the futureis to invent it!is to invent it!
— — Alan KayAlan KayApple FellowApple Fellow
Course Structure
Spiral Learning Online Prelectures (animated textbook, before lecture) Online CheckPoints (check knowledge, before lecture) Lectures (very interactive, bring notes)*** Online Homework (first deadline this Thursday) Discussion Section starts this Thursday Lab Sections start this Wednesday
05
A quick word about Homework
05
More about Homework
05
I understand I understand the material.the material.
I just can’t I just can’t dodo the thehomeworkhomework!!
— — James 1:22James 1:22
Additional Resources
05
ACT 1
Do you have your i>clicker with you today?
A) Yes, and I already registered it!
B) Yes, and I’ll register it tonight!
C) Yes, but it doesn’t work
D) No, but PLEASE give me points anyway!
12
Course Home Page
Planner
07
Course GradebookThis is official grade book, but is manually updated! All lecture and homework points will be updated on weekly. Lab and Discussion activity will be updated weekly.
08
SmartPhysics HomePage
09
SmartPhysics Progress Bars
10
Prelectures + Checkpoints + Lectures 100
Labs 150
Hour exams (3 x 100 each) 300
Final Exam 200
Homework (14) + Quizzes (9) 250
Your Grade (see Course Description)
1000 Points
You may miss up to 3 Prelectures, Checkpoints and 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.
14
Q: What are the benefits of participating ?A: You learn more
0
5
10
15
20
25
30
43 48 52 57 61 65 70 74 78 83 87 91 96 100
Exam Score
ViewerNon-Viewer
Students who… Exam 1 averageViewed pre-lectures 80%Blew through pre-lectures 73%
What we learned in Physics 212
15
Mechanics Lecture 1, Slide 19
Physics 211Lecture 1
Today's Concepts:a) Displacement, Velocity, Accelerationb) 1-D Kinematics with constant acceleration
If you haven't done Prelecture 1 yet, please do so later today
25
Prelecture Example
25
Prelecture Example
26
Displacement
Time taken
Displacement and Velocity in One Dimension
27
Definition:
Speed = |v(t)|
The v(t) vs. t plot is just the slope of the x(t) vs. t plot
Displacement and Velocity in One Dimension
28
A) YESB) NO
Are the plots shown at the left correctly related
Displacement and Velocity in One Dimension
30
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?
AA BB CC
ACT
32
Acceleration
33
For the Displacement and Velocity curves shown on the left, which is the correct plot of acceleration vs. time?
AA
BB
Checkpoint 1
35
AA
BB
For negative t, v(t) is decreasing so its derivative, a(t), must be negative. For positive t, v(t) is increasing so a(t) must be positive.
Typical A answer
a(t) = slope of v(t).... v(t) decreases then increases (never going negative)... this is confirmed by the displacement graph
Typical B answer
Vote againACT 4
37
A ball is thrown straight up in the air.Its position as a function of time is shownin the plot to the right.
Which of the following statements is true as the ball goes up?
A)The acceleration is positive and the ball speeds upB)The acceleration is negative and the ball speeds upC)The acceleration is positive and the ball slows downD)The acceleration is negative and the ball slows down
Acceleration ACT
40
Constant Acceleration
constanta(t) = a
42
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 feetRamp Demo
Checkpoint 2
45
Using the given information, the ball moves 1 foot in 1 second, so it must be accelerating at a rate of 1 foot per second per second. Between time=1 and time=2 seconds, the ball accelerates to 2 feet per second per second, so it travels 2 feet.
Typical B answer
when the ball moves one foot during t=0 to t=1 the acceleration is 2. The ball will move 4 feet from t=0 to t=2 with velocity 2. therefore from t=1 to t=2 it will move 4-1=3
Typical C answer
Since the ball moves 1 foot between t = 0 and t = 1 at constant acceleration, the ball will move the same distance between t = 1 and t = 2.
Typical A answer
Checkpoint 2 Responses
50
Using the given information, the ball moves 1 foot in 1 second, so it must be accelerating at a rate of 1 foot per second per second. Between time=1 and time=2 seconds, the ball accelerates to 2 feet per second per second, so it travels 2 feet.
Typical B answer
when the ball moves one foot during t=0 to t=1 the acceleration is 2. The ball will move 4 feet from t=0 to t=2 with velocity 2. therefore from t=1 to t=2 it will move 4-1=3
Typical C answer
Since the ball moves 1 foot between t = 0 and t = 1 at constant acceleration, the ball will move the same distance between t = 1 and t = 2.
Typical A answer
1ft4ft
9ft
3
16ft
Checkpoint 2 Responses
50
Recommended
