1710chap1 Lin 2014 Black White Corrected Exam Times

8/10/2019 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
http://www.masteringphysics.com/http://www.masteringphysics.com/


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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




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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
http://localhost/var/www/apps/conversion/tmp/scratch_1/VTM04AN1.MOV


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Subtracting Vectors
http://localhost/var/www/apps/conversion/tmp/scratch_1/AF_0306.html


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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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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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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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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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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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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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Direction???

r



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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

(+,+)

(-,-)

(-,+)

(+,-)



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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
http://en.wikipedia.org/wiki/File:Triangle_with_notations_2.svg


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The law of sines

2012 exam question
http://en.wikipedia.org/wiki/File:LabeledTriangle.svg


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2012 exam question

2012 exam question


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2012 exam question

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1710chap1 Lin 2014 Black White Corrected Exam Times

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