1710chap1 lin 2014 black white corrected exam times
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PHYSICS 1710.001
MWF 9:009:50 a.m.
Dr. Yuankun Lin
Associate Professor(working on nano-photonics, and 3D nanofabrication using lasers)
Physics Bldg., Room 323
(940) [email protected]
Office Hours: MWF 9:50-10:30 am, and by appointment
mailto:[email protected]:[email protected] -
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Course Orientation
1. Laboratory
2. Course Syllabus
1. Online homework-Masteringphysics
2. Response Cards
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Textbook, response card, online
homework
Textbook: University Physics, 13thEdition, by Young andFreedman.
Hardcover text with MasteringPhysics access
3-hole punched edition with MasteringPhysics access
MasteringPhysics access including e-book for Young/Freedman
Responsive Innovations Response Card, Part No. RCRF-01,
distributed by Turning Technologies, LLC
Homework: www.masteringphysics.com
http://www.masteringphysics.com/http://www.masteringphysics.com/ -
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Attendance/Participation: 5% of your grade will depend upon your attendance and participation in class.
You will be expected to bring your Response Card with you to class, and participatein answering in-class questions.
(Never bring other clickers to help others. I will randomly call names and check.Both students will lose 5% with a false clicker response)
If your card is not working, write down your name in a piece of paper and hand it into me after class
Laptop computers are not allowed in the class room
If you miss a class, you will be confused with new lecture materials and feelboring and frustrated in the class
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UNT policy on non-attendance
Students might be dropped from this course due to
their non-attendance.
Last day for instructors to drop a student for the non-
attendance (WF) is: Nov 21, 2014.
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Exams: 26-Sep, Exam 1Ch. 1-4, 4:00-5:30 PM, ART 223
24-Oct, Exam 2Ch. 5-8, 4:00-5:30 PM, ART 223 (there is atypo for the date in your printed syllabus)
21-Nov, Exam 3Ch. 9, 10, 14, 15, 4:00-5:30 PM, ART 223
comprehensive final exam, 4:00 -6:00 p.m. on Monday,December 8, location: TBA
There will be no makeup exams.
You must show all of your work on your exam papers forfull credit.
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Copy from students exam
A correct answer without steps=== zero credit
equation
number
answer
Equation is right, answer is wrong
===Partial credit
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Grading policy, example
1stexam 15%; 2ndexam 15%; 3rdexam 15%; 30%for the final; 5%additional weighting will be given for your best exam.
Homework 10%
5%for lecture participation
5%for recitation quizzes
Total 100%
Lab Credit: You must enroll separately in Physics 1730 forlaboratory science credit.
Exam 1Exam 2
Exam 3
Final
67 98 108 82
15% 15% 15+5% 30%
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Online Homework 10%
What You Need:
A valid email address
A student access code(Comes in the Student Access Kitthat may have been packaged with your new textbook oryou can purchase access online atwww.masteringphysics.com.)
The ZIP code for your school: 76203
A Course ID: UNTPHYS1710LIN2014
See syllabus for details
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Homework grading policy:
Some HW problems are required to hand in a writtensolution
If you have earned computer credit for a problem, you
must hand in written solution and show sufficient work inyour written HW to retain that credit.
If a online solution is wrong, correctness of the written
solutioncan help you receive up to 90% of full credit.
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Written homework solution
Hand in neatly written solutions in the mailbox
labeled 1710Lin near the south end of the
2ndfloor hallway in the Physics Building by the
same due date and time as for the online
homework.
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Response card
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Registration of response card
You must provide the instructor with the six-
character alpha-numeric code located on the
back of your keypad, immediately
underneath the bar code
You must set the keypad channel to match
that of the receiver in the lecture hall.
Press GO causing the keypad LED to blink
red-green, press 3 and 3, then press go
again.
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Registration of response card
Login learn.unt.edu
Select course PHYS1710
Click course content
Click
Click Register ResponseCard Device ID
And enterthe six-character code.
The code dont contain o (it is zero).
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Testing your response card.
Press GO causing the keypad LED to blink red-green, press 3 and 3, then press go again.
1. Yes
2. No
3. Dude! Not completely
1. 2. 3.
0% 0%0%
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Recitation Sections 204, 208, 209,
TA instructor
Recitation 5%
Recitation sections meets starting from
Wednesday this week
TA will solve all HW problems in recitation
Attending recitation helps you receive 5% forrecitation itself and 10% for finished HW, andimprove your exam score
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PHYS 1710 tutorial sessions
Office hours of six 1710/2220 TAs are integrated
with PIC tutorial sessions
Location: PIC (Second floor in Physics Building)
Will post schedule online. The schedule will coverall week-days from Morning to Evening.
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Difficulty of PHYS 1710 One of the most difficult course in all Universities
Finish your homework
Read your textbook and bring questions to lecture
Finish old exams posted @blackboard
We are working together for a grade of A
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Chap 1
Units,
Physical Quantities,
and Vectors
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Standards of Quantities
Standardized systems
agreed upon by some authority, usually a
governmental body
SISystme International
agreed to in 1960 by an international committee
main system used in this text
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Fundamental Quantities and Their
Units
Quantity SI Unit
Length meter
Mass kilogramTime second
Temperature Kelvin
Electric Current Ampere
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Quantities Used
In mechanics, three basic quantitiesare used
Length
Mass
Time
Will also use derived quantities
These are other quantities can be expressed interms of these
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Length
Units
SImeter, m
Defined in terms of a meterthe distance
traveled by light in a vacuum during a given
time of 1/299 792 458 second
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Mass
Units
SIkilogram, kg
Defined in terms of a kilogram, based on a
specific cylinder kept at the International
Bureau of Standards
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Standard Kilogram
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Time
Units
seconds, s
Defined in terms of the oscillation of
radiation from a cesium atom
US Official Atomic Clock
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Prefixes.
Prefixes correspond topowers of 10
The prefixes can be
used with any baseunits
They are multipliers ofthe base unit
Examples:1 mm = 10-3m1 mg = 10-3g
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Conversion of Units
When units are not consistent, you may need
to convert to appropriate ones
Units can be treated like algebraic quantities
that can cancel each other out
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Conversion
Always include units for every quantity, you
can carry the units through the entire
calculation
Multiply original value by a ratio equal to one
Example
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Uncertainty in Measurements
There is uncertainty in every measurementthis
uncertainty carries over through the calculations
May be due to the apparatus, the experimenter,
and/or the number of measurements made Need a technique to account for this uncertainty
We will use rules for significant figures toapproximate the uncertainty in results of
calculations
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Significant Figures
A significant figure is one that is reliablyknown
Zeros may or may not be significant
Those used to position the decimal point are notsignificant
To remove ambiguity, use scientific notation
In a measurement, the significant figuresinclude the first estimated digit
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Significant Figures, examples
0.0075 m has 2 significant figures
The leading zeros are placeholders only
Can write in scientific notation to show more clearly: 7.5 x10-3m for 2 significant figures
10.0 m has 3 significant figures
The decimal point gives information about the reliability ofthe measurement
1500 m is ambiguous
Use 1.5 x 103m for 2 significant figures
Use 1.50 x 103m for 3 significant figures
Use 1.500 x 103m for 4 significant figures
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Operations with Significant Figures
Multiplying or Dividing
When multiplying or dividing, the number ofsignificant figures in the final answer is thesame as the number of significant figures in
the quantity having the lowest number ofsignificant figures.
Example: 25.57 m x 2.45 m = 62.6 m
2
The 2.45 m limits your result to 3 significantfigures
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Operations with Significant FiguresAdding or
Subtracting
When adding or subtracting, the number of
decimal places in the result should equal the
smallest number of decimal places in any term
in the sum.
Example: 135 cm + 3.25 cm = 138 cm
The 135 cm limits your answer to the units
decimal value
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Vectors and Scalars
A scalar quantityis completely specified by a
single value with an appropriate unit and has
no direction.
A vector quantityis completely described by a
number and appropriate units plus a
direction.
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Vector Notation
When handwritten, use an arrow:
When printed, will be in bold print: A
When dealing with just the magnitude of a vector in
print, an italic letter will be used:Aor |A|
The magnitude of the vector has physical units
The magnitude of a vector is always a positive
number
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Learn to use Vector
Two-dimensional or three-dimensional
motions will use the vector concept
Warning: Lots of students could not solve 2D
or 3D motion problems due to difficulty in
vector
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Equality of Two Vectors
Two vectors are equal
if they have the same
magnitude and the
same direction
A= BifA= Band they
point along parallel
lines All of the vectors
shown are equal
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Adding Vectors
When adding vectors, their directions must be
taken into account
Units must be the same
Graphical Methods
Use scale drawings
Algebraic Methods
More convenient
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Adding Vectors Graphically
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Subtracting Vectors
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Adding or Subtracting Vectors
Algebraically
Two methods:
Use law of cosines, law of sines
or
Use component method (generally preferred)
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Components of a Vector
A componentis a part
It is useful to use rectangular
components These are the projections of the
vector along the x- and y-axes
Ax and Ayare the component
vectorsof A
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Components of a Vector, 2
The x-component of a vector is the projection
along the x-axis:
The y-component of a vector is the projection
along the y-axis:
Then, A = AX +AY
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Components of a Vector, 3
To obtain the original
vector from its
components, we can
add them as shown
graphically here:
(Remember that the
order of addition isnot important.)
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Components of a Vector, 4
The previous equations are valid only if ismeasured with respect to the x-axis
The components are the legs of the right trianglewhose hypotenuse is A
May still have to find with respect to the positivex-axis
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Unit Vectors
A unit vectoris a dimensionless vector with a
magnitude of exactly 1.
Unit vectors are used to specify a direction
and have no other physical significance
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Unit Vectors, cont.
The symbols i, j, andk
represent unit vectors
They form a set ofmutually
perpendicular vectors
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Unit Vectors in Vector Notation
Axis the same asAxandAyis the same as
Ay
etc.
The complete vector
can be expressed as
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Adding Vectors Using Unit Vectors
Using R= A+ B
Then
and so Rx=Ax+ Bxand Ry=Ay+ By
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Find the sum of A = 2i + 5jk and
B= 4i -2j+ 7k.
1. 6i +9k
2. 6i + 7j + 8k
3. 6i + 3j + 6k4. 8i - 10j - 7k
1 2 3 4
0% 0%0%0%
Response
Counter
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A = 2i + 5jk
B= 4i -2j+ 7k
F ind R=3A+2B?
3A=3(2i+5j-k) = 6i+15j -3k2B=2(4i-2j+7k) = 8i -4j+14k
R=14i+11j+11k
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Fall 2011 exam question
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D t d t
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Dot product
answer: scaler
A=Axi+Ayj+Azk
B=Bxi+Byj+Bzk
A dot B=AxBx+AyBy+AzBz
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Consider the two vectors
A=3i+4j
B=-8i+6j
A. zero
B. 14
C. 48
D. 50
E. none of these
What is the dot product A
B
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Consider the two vectors
A=3i-4j
B=6k
What is the dot product A
B
A. zeroB.6
C. +6
D. 42
E.42
2012 ti
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2012 exam question
Cross product
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pright hand rule
A B=|A | |B | sin
is the angle between A and B
i j=k
j k=i k i=j
j i=-k
k j=-i
i k=-j
i i=0
j j=0
k k=0
Cross product, my rule
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p , y
i j k i j k i j k i j k
Next Neighbor
Left to right, +, right to left, -
Cross product
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Cross product
answer still vector
Very often it is not necessary to use determinantformula
A simple math can do (see next slide)
id h
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Consider the two vectors
A=3i+4j
B=-8i+6j
A. +6k
B. -6k
C. 50k
D. -50kE. none of these
What is the cross product AB
=3 i(-8i+6j)+4 j(-8i+6j)
=18k-32(-k)=50 k
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Consider the two vectors
A=3i-4j
B=6k
What is the dot product AB
A. zeroB. 24i+18j
C. -24i-18j
D. 18i-24j
E. 18i-24j
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Fall 2011 Exam question
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Fall 2011 Exam question
Direction???
r
Fall 2011 Exam question
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Fall 2011 Exam question
Direction???
Or using right hand ruler
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Cartesian Coordinate System
common in this course x- and y- axes
intersect at the origin
Points are labeled (x,y)
Four regions, called
quadrants
(+,+)
(-,-)
(-,+)
(+,-)
Cartesian Coordinate System
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Cartesian Coordinate System
common in this course
Vector OP=(5,3)
Or OP=5 i+ 3 j
Vector OQ=(-3, 4)
Vector QP=OP-OQ
=(5, 3)-(-3,4)
=(8, -1)
Which region is the vector QP located
(+,+)
(-,-)
(-,+)
(+,-)
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Which region is the vector QP
located
Vector QP=(8, -1)
In region IV
The head of the vector in region IV
(+,+)
(-,-)
(-,+)
(+,-)
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Example
Starting from his house, a boy walks 10 malong a street 30North of East, walks 20
m toward the East, and then walks 5 m
towards the North. Whats the straightdistance of the boy from his house?
Using vectors
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gcalculate vector component
Starting from his house, a boy walks 10 m along a street 30North of East, walks 20 m
toward the East, and then walks 5 m towards the North. Whats the straight distance ofthe boy from his house?
1020
5
by adding vectors
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R=A+B+CStarting from his house, a boy walks 10 m along a street 30North of East, walks20 m toward the East, and then walks 5 m towards the North. Whats the straightdistance of the boy from his house?
A=10 cos 30 i+10 sin30 j
B= 20 i+0 jC= 0 i+ 5 j
AB
C
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The law of cosines
Adding vectors
Subtracting vectors
h l f
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The law of sines
2012 exam question
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2012 exam question
2012 exam question
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2012 exam question