Newtonian Mechanics
8.01
W01D2
Why Study Physics
Textbook
Authors: Young and Freedman
University Physics 13th Edition Volume 1
In-Class Active Participation
Students are expected to complete daily reading
assignments and hand in answers before the class
Active Participation:
 Concept Questions using Turning Point Clickers
 Short Group/Table Problems with student presentation of
work at boards
 Mini-experiments and quantitative experiments
Weekly Schedule
Mon/Tue: In-Class (2 hr): Hand in Answers to Mon/Tues Reading
Question, Presentations, Concept Tests, Table Problems.
Tue Night: Hand Written Problem Set due 9 pm, Math Review Nights 9-11
pm.
Wed/Thurs: In-Class (2 hr): Hand in Answers to Wed/Thur Reading
Questions, Presentation, Concept Tests, Table Problems, Experiments
Fri In-Class (1 hr): Hand in Answers to Fri Reading Questions, Group
Problem Solving, Mini-experiments.
Sun: Tutoring Center Help Sessions from 1-5 pm in 26-152
Office Hours: Faculty and TA office hours throughout the week
Problem Solving
A MIT Education requires solving 10,000 Problems
Measure understanding in technical and scientific courses
Regular practice
Expert Problem Solvers:
Problem solving requires factual and procedural knowledge, knowledge
of numerous models, plus skill in overall problem solving.
Problems should not ‘lead students by the nose” but integrate synthetic
and analytic understanding
Problem Solving/Exams
In-Class Concept Questions and Table Problems
In-Class Group Problems (Friday)
Weekly Problem Sets
1. Multi-concept analytic problems
2. Pre-class Reading Questions
3. Pre-lab questions and analyze data from experiments
Online “Mastering Physics” Practice Assignments:
1. One practice assignment per week with hints and tutorials
2. Review problems for exams
Exams: Three Evening Exams and Final Exam
Guidelines for Collaboration
Problem Sets:
Please work together BUT
Submit your own, uncopied work
In Class Assignments:
Must sign your own name to submitted work
Signing another’s name is prohibited
In Class Concept Questions:
Use only your clicker
Using another’s clicker is prohibited
8
Exam Dates
Exam 1: Thurs Sept 22, 7:30 pm -9:30 pm
Conflict Exam 1: Fri Sept 23, 9:00 am - noon
Exam 2: Thurs Oct 27, 7:30 pm -9:30 pm
Conflict Exam 2: Friday Oct 28, 9:00 am - noon
Exam 3: Tues Nov 22, 7:30 pm -9:30 pm (Thanksgiving week)
Conflict Exam 3: Wed Nov 23, 9:00 am - noon
Final Exam: Date/time to be announced by Registrar
Please do not buy plane tickets home without consulting
these dates, especially for the Thanksgiving holiday.
Grading Policy
 3 Exams + Final Exam
= 15%+15%+15%+25% = 70% (Individual
Work)
You must pass the exam portion in order
to pass the course.




Problem Sets 10% (Individual Work)
Reading Questions 5% (Individual Work)
Concept Questions 5% (Group Work)
In Class Work 10%: Experiments (Group
Work) and Friday Problem Solving (Group
Work)
Registering “Mastering Physics”
(See instructions at mastering physics sign up info)
 Go to http://www.masteringphysics.com
 Register with the access code in the front of the
access kit in your new text, or pay with a credit
card if you bought a used book.
 WRITE DOWN YOUR NAME AND PASSWORD
 Log on to masteringphysics.com with your new
name and password.
 The MIT zip code is 02139
 The Course ID: MPDOURMASHKIN40470
Website: web.mit.edu/8.01t/www
1. Course Information/Announcements
2. Daily Class Schedule
3. Presentations
4. Concept Questions and Solutions
5. Group Problems and Solutions
6. Experiments Write-ups
7. Problem Set Assignments and Solutions
8. Course Notes
9. Math Review Night Presentations
10. Exam Prep
11. Office and Tutoring Hours
Stellar Site for Course Gradebook
8.01, 8.012, or 8.01L: which
course is best suited for me?
Reasons for Working in Groups
 Develop collaborative learning skills
 Develop communication skills in Core Sciences
 Create an environment conducive to learning and
teaching for everyone in the class
 Opportunity to ask teachers and peers more questions
 Research labs or work places depend on group
interactions
Coordinate Systems
Cartesian Coordinate System
Coordinate system: used to describe the position
of a point in space and consists of
1. An origin as the
reference point
2. A set of coordinate
axes with scales and
labels
3. Choice of positive
direction for each axis
Cartesian Coordinate System
Vectors
Vector Reading Assignment:
Young and Freedman: University Physics
13th edition: 1.7-1.9
12th edition: 1.7-1.9
Vector
A vector A is a
quantity that has both
direction and
magnitude.
The magnitude of
is denoted by
| A | A
Application of Vectors
(1) Vectors can exist at any point P in space.
(2) Vectors have direction and magnitude.
(3) Vector equality: Any two vectors that have
the same direction and magnitude are equal
no matter where in space they are located.
Vector Addition
Let A and B be two vectors. Define a
new vector C  A  B , the “vector
addition” of A and B , by the geometric
construction shown in either figure
“head-to-tail”
“parallelogram”
Vector Decomposition
Choose a coordinate system with an origin and axes. We
can decompose a vector into component vectors along
each coordinate axis, for example along the x, y, and z-axes
of a Cartesian coordinate system. A vector at P can be
decomposed into the vector sum:
A  Ax  A y  Az
Unit Vectors and Components
The idea of multiplication by real numbers allows us
to define a set of unit vectors at each point in space
ˆ ) with |ˆi | 1, | ˆj | 1, | kˆ | 1
(ˆi , ˆj, k
r r
r
r
Then vector decomposition A  A x  A y  A z becomes
with components vectors: A x  Ax ˆi , A y  Ay ˆj, A z  Az kˆ
and components: A  ( Ax , Ay , Az )
ˆ
Thus
A  Ax ˆi  Ay ˆj  Az k
Vector Decomposition in Two
Dimensions
Consider a vector
A  ( Ax , Ay ,0)
x- and y components:
Ax  Acos( ), Ay  Asin( )
A
Magnitude:
Direction:
Ax2  Ay2
Asin( )

 tan( )
Ax Acos( )
Ay
  tan 1 ( Ay / Ax )
Vector Addition
A  A cos( A ) î  Asin( A ) ĵ
B  B cos( B ) î  Bsin( B ) ĵ
Vector Sum:
Components
Cx  Ax  Bx ,
C AB
C y  Ay  By
Cx  C cos(C )  A cos( A ) B cos( B )
Cy  C sin(C )  Asin( A )  Bsin( B )
C  ( Ax  Bx ) ˆi  ( Ay  By ) ˆj  C cos(C ) ˆi  C sin(C ) ˆj
Worked Examples and Table
Problems: Vectors
r
A2φ
i  3 φ
j  7 kφ
Given two vectors,
find:
(a)
r
A
(b)
r
B
(c)
r r
AB
(d)
r r
AB
r
B  5φ
iφ
j  2kφ
(e) a unit vector
φ
A
r
pointing in the direction of A
(f) a unit vector
Bφ
r
pointing in the direction of B
Table Problem: Vector
Decomposition
Two horizontal ropes are attached to a post that is
stuck in the ground. The ropes pull the post
r
producing the vector forces A  70 N φi  20 N φj
r
and
as shown in the figure.
B  30 N φ
i  40 N φ
j
Find the direction and magnitude of the horizontal
component of a third force on the post that will
make the vector sum of forces on the post equal to
zero.
Preview: Vector Description of
Motion
1. Position
r (t )  x(t )ˆi  y (t )ˆj
2. Displacement
3. Velocity
r (t )  x(t ) ˆi  y (t ) ˆj
dx(t ) ˆ dy (t ) ˆ
v(t ) 
i
j  vx (t )ˆi  v y (t )ˆj
dt
dt
4. Acceleration
dvx (t ) ˆ dv y (t ) ˆ
a(t ) 
i
j  ax (t )ˆi  a y (t )ˆj
dt
dt
Table Problem: Displacement
Vector
At 2 am one morning, a person runs 250 m
along the Infinite Corridor at MIT from Mass
Ave to the end of Building 8, turns right at
the end of the corridor and runs 178 m to
the end of Building 2, and then turns right
and runs 30 m down the hall.
What is the direction and magnitude of the
displacement vector between start and
finish?
Things to Do For W01D3
•
•
•
•
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Buy a Textbook (12th ed., or 13th ed.)
Get “Mastering Physics” (comes with new
textbook or purchase separately) and register
Buy Clicker at MIT Coop
Reading Assignment: Young and Freedman
Sections 1.7-1.9, 2.1-2.6
Answer Reading Questions Posted on Friday’s
webpage to be handed in before class on friday