Olson Phy 121 Homework 3

Welcome to Physics 123 (section 2)!Fall 2012NOTE: Section 2 is for Physics majors and minors only, or (with my permission) for people who are seriously considering a major/minor.

Instructor: John S. Colton
Email address: "john_" (including the underscore) plus "colton" at byu.edu
Office hours: MWF 2-3 pm, in the Underground Lab study area
Office: N335 ESC, meetings available by appointment

T.A./grader: Clément Gaillard
TA's email address: clement.byuta@gmail.com
TA's office hours: MWF 3-4:30 pm, in the Underground Lab study area


  • 11 May 2012 - barebones website set up
  • 5 Jul 2012 - syllabus posted


  • The main textbook for the class is Physics for Scientists and Engineers, by Serway and Jewett (6th, 7th, or 8th editions). You will need a textbook, or combination of textbooks, that covers chapters 14, 16-22, and 35-39. Inexpensive used versions are perfectly acceptable.
  • A small auxiliary textbook will be Physics phor Phynatics, by Dallin Durfee (a faculty member here at BYU). This book contains supplementary material specific to this section of 123. It is a very inexpensive book, and Dr. Durfee does not receive any royalties.

Syllabus and Course Packet

  • Phys 123 section 2 syllabus.pdf - The syllabus will also be available in the bookstore for purchase, for $5-6. If you prefer, you can print out your own copy from the pdf file--but if you do so, please don't use department printers unless you reimburse the department for the expense.

Warm-up Exercises

Lecture Notes

  • Some students like to print out lecture notes before the lectures, for use in taking notes. If you want to do that, you can use my lectures from last semester. This semester's lectures will likely be fairly similar to those lectures.
  • lecture 1 - intro, pressure
  • lecture 2 - Archimedes' principle
  • lecture 3 - fluid motion
  • lecture 4 - thermal expansion, ideal gas law
  • lecture 5 - kinetic theory (note: we didn't get to the last couple of slides, but we'll pick up there next lecture)
  • lecture 6 - calorimetry
  • lecture 7 - heat transfer
  • lecture 8 - first law
  • lecture 9 - molar specific heats
  • lecture 10 - engines
  • lecture 11 - refrigerators and Carnot
  • lecture 12 - entropy
  • lecture 13 - what is entropy
  • lecture 14 - waves (note: we didn't get to the last couple of slides, but we'll pick up there next lecture)
  • lecture 15 - waves on a string
  • lecture 16 - complex numbers (Note: we didn't get to the last 4 slides. We'll start there next time.)
  • lecture 17 - reflection, transmission, sound intro (Note: we didn't get to start the stuff on sound)
  • lecture 18 - sound - intensity, doppler
  • lecture 19 - superposition, standing waves
  • lecture 20 - more standing waves, resonance
  • lecture 21 - wave packets, dispersion (Note: we didn't get to the last 2 slides, but that's OK. They relate to the next lecture.)
  • lecture 22 - Fourier 1
  • lecture 23 - Fourier 2
  • lecture 24 - music
  • lecture 25 - reflection, refraction, dispersion
  • lecture 26 - Huygen, TIR
  • lecture 27 - polarization, Brewster
  • lecture 28 - images from mirrors
  • lecture 29 - images from lenses
  • lecture 30 - aberrations, camera, eye
  • lecture 31 - magnifier, telescope (Note: we didn't get to the last slide, but we'll talk about it next lecture)
  • lecture 32 - interference from slits
  • lecture 33 - more interference
  • lecture 34 - diffraction from wide slits
  • lecture 35 - resolving, gratings
  • lecture 36 - waves in 3 dimensions, optical devices
  • lecture 37 - intro to relativity
  • lecture 38 - special relativity
  • lecture 39 - Lorentz transformations 1
  • lecture 40 - Lorentz transformations 2
  • lecture 41 - E=mc^2

Videos of Demos

Loading movie...

If you are unable to see the movie, make sure you have Javascript enabled and have the latest Flash Player.

Here are a lot of the demos I have done/likely will do in class this semester, posted here in case you have to miss a class. The videos were filmed in old Phys 123 and Phys 105 classes. Click on the demo title to get it to play in the movie window.

  • lecture 1 - force vs pressure | collapsing can | Magdeburg hemispheres
  • lecture 2 - bed of nails | reverse tug of war | Coke vs Diet Coke | aluminum foil sink or float | force from submerged weight (we skipped the aluminum foil one, and did force from submerged weight in lecture 3)
  • lecture 3 - chimney effect | cards and wooden block | ball in funnel | floating ball | blowing on paper | Bernoulli red fluid 
  • lecture 4 - liquid bulb thermometer | pressure gauge thermometer | bimetallic strip | ring and ball | helium vs air balloon | LN volume expansion | LN balloon pop | rubber nail  (we didn't do the last two, but they may be fun for you to watch)
  • lecture 5 - lighter molecules go faster | fast molecules cause pressure (we didn't get to the last demo, but we'll do it at the start of next lecture)
  • lecture 6 - boiling water at 300K
  • lecture 7 - failed attempted at boiling water in a paper cup--sorry, no video | here's a convection demo from a previous semester: convection current
  • lecture 9 - alcohol rocket (aka constant volume change) | freeze spray | adiabatic cotton burner (this is a larger version of the one that I used in class)
  • lecture 11 - Stirling engine | thermoelectric engine (not recorded)
  • lecture 14 - Slinky - longitudinal and transverse waves
  • lecture 15 - tubing - wavespeed depends on tension | predicting wave speed ( v = sqrt(T/mu) ) | Shive wave machine - amplitudes add or subtract | 6 still shots of the amplitudes subtracting | Here's another one we won't do, but which may be helpful to some of you: spring vs circular motion
  • lecture 17 - Reflection at boundary
  • lecture 18 - no sound in a vacuum | tuning forks | singing rod | Joy to the World (with compressed air hose) | Doppler effect | hearing test (note that I don't know if the microphone picked up the highest frequencies, because I myself can't hear them!) 
  • lecture 19 - two speaker interference | standing waves on a rubber tube | lady's belt and jigsaw
  • lecture 20 - trumpet harmonics (note in the recording I said "even without using notes" where I meant "without using valves")  | flame standing waves | beats
  • lecture 23 - waves on a slinky: initial shape of triangle | square pulse (happened too quickly to capture on video, sorry)
  • lecture 25 - basic reflection and refraction (sorry, no video)
  • lecture 26 - TIR in a stream of water | fiber optic - large fiber | fiber optic - actual size fibers (sorry, no video for the fiber optics demos)
  • lecture 27 - light coming through three polarizers (sorry, no video) | light reflecting at brewster angle
  • lecture 28 - mirror real image or not | filament reflected in bulb | hanging ball pendulum
  • lecture 29 - lens real image or not | covering up half of the lens (sorry, no video)
  • lecture 32 - diffraction from a double slit
  • lecture 33 - interference from a thin film
  • lecture 34 - diffraction from a single wide slit | measuring the width of a hair (we didn't do this in lecture 34, but will do it in lecture 35)
  • lecture 35 - diffraction from a grating


Scores and Grade

Class Identification Numbers

I-Clicker registration


  • Instructions for all the labs, along with the sheets which must be turned in, can be found in the main syllabus packet following the homework problems. Due-dates for the labs are shown on the main schedule, the first page of the syllabus.
  • All but two of the labs are similar to the "walk-in" labs of Physics 121. They will be set up in room S415 ESC on the dates indicated on the schedule.
  • Two of the labs involve computer simulations. Follow these links to get more information for those labs:

Term Project Info

Selected Term Projects From The Class

  • Collision Simulator, by Ryan Peterson
  • Hot air balloon videos, by Hsin Ping Chang, Konrie Ming, Dallin Barton: attempt 1, attempt 2,
  • Musical cadence app, by Cade Daniel and Seth Poulsen (right-click to download, unzip to a folder with the "media" subfolder in the same place as the SemesterProject.exe file )
  • Spanish Speech Synthesizer, by Chris Olsen, Will Nuckolls, and Jacob Ward (download the zip file, unzip into a directory, then open the Mathematica file)
  • Two "super cool" videos of supercooled water, by Kristoffer Molinari and Lance James, flash freeze, pouring ice
  • Attempts to study backspin, by Josh Porter and Michael Pearson:

Tutorial Lab Info

Old Exams

Here are some old exams for you to use as study aids. I strongly recommend that you attempt to work the problems on the actual exams before looking at my solutions. There's no guarantee that this year's 123 exams will be the same as any of these posted exams, in terms of multiple choice/not multiple choice, time limit/no time limit, notes/no notes, calculators/no calculators, difficulty level and so forth. It is likely that I will not let students use any notes on the exams, but rather I will provide some (but not all!) equations on the first page, like this sample first page of exams.

This semester's exams

How to get started

  • You need to do the following things as soon as the semester begins. (If you have added the class late, it's even more important to do them ASAP.)
    → If you have not received one in an email, get a "class ID number" using the "Obtain your class ID number" link on this page. You will use the CID as your personal identifier for all your assignments.
    → Read the syllabus, available either as a pdf file elsewhere on this web page, or from the bookstore. Among other things, the HW problems are found in the syllabus.
    → Get a copy of the Serway & Jewett textbook (see textbook info, elsewhere on this web page). If you can't get one soon, you can use one of the copies available in the Tutorial Lab (see Tutorial Lab info elsewhere on this web page).
    → Do the reading assignments for each upcoming lecture as marked on the schedule on pg 1 of the syllabus; if joining late, do the past reading assignments.
    → Do the first "warmup exercise" by midnight on Monday, 27 Aug 2012. Links to warmups are above.
    → Do the other warmup exercises before class for each upcoming lecture, due at 12:15 pm the day of the lecture.
    → Get an "i-clicker" at the bookstore if you don't already have one. Bring your clicker to each class.
    → Register your clicker (via the link elsewhere on this page) so that you get credit for in-class clicker quizzes.
    → Get your individualized homework data numbers which you will plug into the HW problems in your syllabus, using the "Print HW data sheet" link on this page.
    → Start working HW problems! The first assignment is due Wed, Sep 1. You can get credit for late assignments, so work the HW sets you miss/have missed, in addition to the ones coming up. The syllabus has much more about how to turn in HW problems.
    → Where required, submit your computer-graded HW answers via the online system using the "Submit HW" link. Again, read how to do this in the HW section of the syllabus. Learn how to get partial credit by re-submitting the problems you get wrong. Talk to other students to figure this out, if necessary. HW due-dates are marked on page 1 of the syllabus.
    → Be sure to turn in the work for your HW problems to the slot labeled “Phys 123, section 2” in boxes near room N375 ESC.
    → Sign up for a departmental computer account if you don't have one already.
    → Gain access to the departmental computer labs (N337 and N212) by talking to Diann Sorenson in room N281.


  • Dr. Colton's Basic Commands of Mathematica document. (Must be opened with Mathematica.)
  • BYU Physics Department's website for Physics 230, where among other things a number of introductory computational labs can be downloaded (if you want even more Mathematica than in my "Basic Commands" document).

Math Review

Supplementary Material

Current Topics in Physics

Frequently Asked Questions about the 12x Labs

General Information

Make-up Labs


General Information ^

How do I get into a lab section that is full?

Please refer to the Overload Instructions located here:


I need to change my section. What do I do?

The instructors for the 1xx series of courses do not handle registration issues. For that we use a professional: Please contact our Program Coordinator Susan Miller, susanh82@phys.washington.edu, in the Physics/Astronomy Bldg, Rm. C-136, phone 206-543-4982, for section changes, add codes, overload requests or other registration matters.

Who is my T.A. And what is his/her email address?

Please refer to the Lab Section/T.A. Info section of your course web page:

PHYS 117: https://courses.washington.edu/phys117
PHYS 118: https://courses.washington.edu/phys118
PHYS 119: https://courses.washington.edu/phys119
PHYS 121: https://courses.washington.edu/phys121z
PHYS 122: https://courses.washington.edu/phys122z
PHYS 123: https://courses.washington.edu/phys123z

If you cannot find your TAs email address on the associated TA Info page for your section, you should be able to find it on the Physics Department's website. Look for the appropriate quarter and course number.

When does my section meet and where is my lab room?

Please see your MyUW time schedule to find when and where your section meets. You may also use the following link to the registrar's time schedule:

Spring 2017 Time Schedule, Physics

Here is a link to a map highlighting where to find PHYS 1xx classrooms:


I have lost something in a lab. Who do I talk to about lost and found?

First talk to your T.A. If your T.A. does not have it and has not turned it in somewhere, talk to the T.A. immediately AFTER the section you attended. Next, talk to Jack Olsen (olsenjr@uw.edu). Finally, talk to the Physics Front Office located in room C-121 of the Physics/Astronomy Building.

What do I need to bring to the lab?

You should bring the following items with you to every class meeting:

  • The lab manual, or at least the pages for the day's lab;
  • A scientific calculator, such as a TI-83 or similar;
  • A pencil or pen;
  • Extra paper or a notebook for calculations.

Learn to use your scientific calculator, especially how to use logarithms, roots and powers, and most important, the statistical functions of finding the mean and sample standard deviation of a set of numbers.

Do I need protective clothing (lab coat, goggles, etc.) for the labs?

No, you do not need protective clothing for the 1xx physics labs. It is rare for hazardous material or procedures to be used in physics labs, and on those rare occasions when you would need protective wear, it will be provided.

Make-up Labs ^

What do I do if I miss a lab?

If you miss your lab session, please try to attend a different section in the same week. You need to obtain permission from the TA of that section and inform him/her of your regular section. It is your responsibility to let your regular TA know that you attended a different section in order for you to get credit for attending the lab. It is better to complete a lab the same week that it is scheduled rather than in the makeup week because subsequent labs may build on it. Also, the number of labs you may make up during the last week is very limited (no more than 2). And, of course, the last week of classes tends to be very busy with finals preparation.

Please note: You may not regularly attend a lab section (or any UW class) that you are not registered for. If you are unable to attend the section you are registered for on a regular basis, you should request a section change.

What happens with the Post-Lab if I miss a lab session? Will I lose points on it too?

If you miss an In-Class session, you may work on the Post-Lab assignment, however, it is recommended that you wait until you complete the In-Class session. If you make-up the In-Class session during the week that the lab is offered, by attending another session, you can complete the post-lab by the usual due date. If, however, you make-up the lab during the make-up week, the due-date for the Post-Lab will be reset to a new date, as long as it has not already been completed.

I missed the lab session. Can I still do the post-lab?

Yes, but it is not recommended unless you have no alternative. Because the Post-Lab draws on what you do in the In-Class session, some questions may use data or concepts that would be covered during the session.

I attended a different lab section than the one I am registered for. Can I email my TA so that I get credit for the in-class part?

No, you must obtain both the TA's initials whose class you attended and the initials of your regular TA in orer to verify your attendance. Anyone could email their TA claiming that they went to another section.

I have a low or a zero score on a Post-Lab. Can I make the whole lab up, and redo the Post-lab?

I missed a Post-Lab, but I did the In-Class session. Can I make-up just the Post-Lab?

No. There are no make-ups on Post-Labs past the 1 week make-up window. The reason that the Post-Lab due date is reset when you make-up the In-Class session during make-up week is because you really should do the In-Class session before attempting the Post-Lab. If you already did the In-Class session, you had enough information to do a good job on the Post-Lab.

The score for the Post-Lab may be excused if you have a valid reason for missing it, but there are no make-ups on Post-Labs alone (past the usual window).

When is the make-up week? When and where can I sign up for the make-up?

A lab make-up sign-up will be made available during the last weeks of the quarter. It may be a web-based or paper-based sign up, depending on the particular lab instructor's practice. Paper sign-up sheets are usually posted in the lab room if these are being used.

The make-up week itself occurs during the last full week of classes.

How many make-up sessions are there? Will there be a make-up session during my regular time?

The number of make-up sessions depends on the number of people needing to make-up a lab, and thus there will not be as many make-up sessions as there are regular section meetings during the make-up week. Usually there are somewhere between 1/3 to 1/2 of the usual meeting times made available for make-ups. These make-up sessions are run during time periods allotted for the usual sections, so you may have one during your usual time, but this is not guaranteed.

Where are the make-up labs held?

The make-up labs are held in the same group of rooms used for the regular lab meeetings, however, the meeting for a particular experment may not be in the same room that your section met in. You should go to your usual lab room, look for the TA, and ask him or her where your make-up experiment is set-up. The reason for the ambiguity is that we do not know how many of each experiment will be needed until the make-up sessions start.

Grades ^

Who should I contact if I have a missing grade on my transcript (an X instead of a number grade)?

You should contact your T.A. and and the lab professor for that series. The lab professor will then need to complete out a change of grade form and submit it to the Registrar.


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