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8/27/2013 PHY 113 A Fall 2013 -- Lecture 1 1

PHY 113 C General Physics I11 AM-12:15 PM TR Olin 101

Plan for Lecture 1:

1. Welcome & overview

2. Class structure & announcements

3. Chapter 1 – measurement & units

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PHY 113 A General Physics I11 AM-12:15 PM TR Olin 101

Instructor: Natalie Holzwarth (Olin 300)Course Webpage: http://www.wfu.edu/~natalie/f13phy113

Text: Physics for Scientists and Engineers with Modern Physics by Serwey and Jewett, 9th edition*

Webpage for Webassign system:http://www.webassign.net/

You will also need ani-clicker device for each class

A scientific calculator will be needed for homework and exams----------------*May replace with used texts including 8th edition versions.

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Where to find information about the course on the web: http://users.wfu.edu/natalie/f13phy113

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Comment about Physics Colloquia

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Course organization: http://users.wfu.edu/natalie/f13phy113/info/

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http://users.wfu.edu/natalie/f13phy113/homework/

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www.webassign.net

Username = wfu email ID (without @wfu.edu)Institution = wfuPassword = PHYSICSROCKS (change ASAP)

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www.webassign.net

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Problem solving steps1. Visualize problem – labeling

variables2. Determine which basic physical

principle(s) apply3. Write down the appropriate

equations using the variables defined in step 1.

4. Check whether you have the correct amount of information to solve the problem (same number of knownsand unknowns).

5. Solve the equations.6. Check whether your answer makes

sense (units, order of magnitude, etc.).

L=111 ft

W=63 ft

area = width * length

A = W * L

OK

2

2

m649.2ft3.282

m1ft 111ft 63

A

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sst

VRa gal/0.033min/60min 5

gal10)

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i>clicker exercises:

Which of the following options do you prefer for the number of exams in the course?

A. 3 examsB. 2 exams

Which of the following options do you prefer for the exam times?

A. Exams within class time (75 minutes)B. Exams offered outside of class time

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i>clicker exercise:

Preferences for tutorial times: (Sunday – Thursday)A. 5:30-7:30 PMB. 6-8 PMC. 7-9 PMD. 8-10 PME. Other

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PHY 113 Labs will start Monday Sept. 3rd

and run through the week of Nov. 16th. There will be no labs during Thanksgiving week.

PHY 113 Tutorial sessions will also start next week.

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General advice on how to learn physics:

Physics is built on basic principles (“laws”) from which all results can be derived (deduced)

Focus your attention on understanding the basic principles Practice using these basic principles to solve problems Memorization is of little use in the study and practice of physics

Note: In general, the best way to learn physics is to practice problem solving. One benefit of learning physics is the development of general problem solving skills. Note that memorization of the text and lecture material is rarely useful.

As you are working problems, you may wish to construct a sheet of paper containing the basic equations you use. This basic equation sheet (8.5 in x 11 in) can be used during exams.

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Advice:

1. Keep basic concepts and equations at the top of your head.

2. Practice problem solving and math skills

3. Develop an equation sheet that you can consult.

Equation Sheet

dtddtdm

rv

va

aF

Problem solving skills

Math skills

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Problem solving steps

1. Visualize problem – labeling variables2. Determine which basic physical principle(s) apply3. Write down the appropriate equations using the

variables defined in step 1.4. Check whether you have the correct amount of

information to solve the problem (same number of knowns and unknowns).

5. Solve the equations.6. Check whether your answer makes sense (units,

order of magnitude, etc.).

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y (m

)

x (m)8/27/2013 PHY 113 A Fall 2013 -- Lecture 1 21

The Zeroth Law of Physics

All physical phenomena can be analyzed using fundamental “laws” which are stated in terms of basic concepts and represented in terms of mathematical expressions and equations.

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i>clicker exercise:

Why would a physicist (or anyone else) want to know that the ball follows a parabolic trajectory?

A. Because it tests the basic principles of physics.B. Because it can help a golfer get a hole in one.C. Because it shows that gravity is effecting the

motion of the ball.D. Because it shows a contrast with straight line

motion.E. Because it makes you look smart.

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The Zeroth Law of Physics

All physical phenomena can be analyzed using fundamental “laws” which are stated in terms of basic concepts and represented in terms of mathematical expressions and equations.

In order to perform the analysis, it is necessary to have standard units to measure the quantities of interest – time, distance, mass, etc.

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Measurement units

Standard units “SI” (by international agreement in 1960)

length – metermass -- kilogramtime -- second

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http://www.nist.gov/pml/wmd/metric/length.cfm

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http://www.nist.gov/pml/wmd/metric/mass.cfm

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http://www.nist.gov/pml/wmd/metric/time.cfm

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Terrible example: 1012 bull

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Comments about errors in measurement

cm1.03

cm3.1cm2.9cm1.03

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Comments about errors in measurement -- continued

cm1.03L

cm1.02w

cm1.03cm1.02area wLA

i>clicker exercise:What should we do about this?A. Leave it as is?B. Expand the expression?C. Run away screaming?

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Comments about errors in measurement -- continued

cm1.03L

cm1.02w

cm1.03cm1.02area wLA

cm0.56

cm01.03.02.06cm1.01.031.01.0232

cm1.03cm1.02

2

2

2

wLA

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Comments about errors in measurement -- continued

cm1.03L

cm1.02w

cm1.03cm1.02area wLA

ww

LL

AA

ww

LL

AA

LwwLwLLwLw

AAA

wLwLLwLwLwLLAA

11

:calculusandalgebrasimpleUsing

08333.021.0

31.0:caseour In

AA

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Comment on significant figures

In my opinion the notion of significant figures is more trouble than it is worth and is given more ink (pixels) than it deserves.

If you are performing a calculation, NEVER round your answer except possibly after the last step.

kg3.03.7report toreasonablebeIt wouldkg621.7Mkg021.7 that meansThis

kg3.0321.7measureyou Suppose:Example

MM

MM

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Reminders • Contact me (Olin 300, x5510, natalie@wfu.edu)

with any questions, concerns, etc.• Before next class: skim Chapter 1 and read

Chapter 2 of textbook; Email natalie@wfu.edu with a question concerning one-dimensional motion

• Try practice problems in webassign.net(Assignment 1)

• Bring i>clickers to class