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PHYS 121 A: Mechanics

Summer Term: 
Meeting Time: 
TTh 10:50am - 12:20pm
* *
Brian Stephanik

Syllabus Description:

Topics covered

Physics 121 addresses the following topics:

  • one dimensional kinematics
  • momentum
  • energy
  • relative motion
  • forces
  • work
  • motion in two or more dimensions
  • circular motions
  • rotational kinematics and dynamics
  • angular momentum
  • gravity


This course has multiple components lecture, lab, and tutorial (QZ section in time schedule) each of which have several important aspects.  These are described below after some general information critical to success in this course.

Resources to Succeed

This website describes recommended practices to succeed in this course and contains a list of resources you may find helpful for a variety of issues you may encounter during your time at UW.  Contact us if you need help finding the resources you need.

One very important practice described in the above website is working collaboratively. We will create a space for you to communicate with your peers in your tutorial section and TA in a Slack channel. See Getting Started for more details.  However, you are encouraged to reach out to other students to find people with whom you can study and learn.

To organize your coursework, we have posted sample weekly schedule here.  We recommend downloading it and make your own by moving various cells (except the due dates in red cells). For example, move the cell corresponding to “Attend Tutorial” to the time of your actual tutorial (QZ) section, move the time when you will watch the lecture videos to a time that works for you, etc. (Note: since the lecture portion this quarter is taught asynchronously, you will likely find that watching lectures throughout the week is more convenient and digestible than only twice per week).

Office Hours and Posting Questions

During the week we (the TAs and Instructors) will hold office hours on Zoom where you can ask questions.  Click Office hours for the office hour schedule. 

Use Slack (sign-up using your UW email at the link here) for physics questions or syllabus related questions.  Students are encouraged to answer each others' questions, but we will also monitor this frequently and will respond if needed.

Contact information

For questions send an email to the instructor, (Brian Stephanik) at with your course (Phys 121), your UW netID (the part before in your email address), and name as it appears on Canvas to your section lecturer for lecture-related questions and for personal correspondence related to grades, health issues, etc.

For Lab and Tutorial questions, please contact your TA (contact information here) or the PHYS 121 TA coordinator (David Smith) at for questions about your TA or questions that your TA may not be able to answer.

For administrator questions related to registering, overloading, etc contact the program coordinator at

Course Material

You need to purchase the following items:

  • The Tutorial Course Pack,
  • Access code for MyLab and Mastering,
    • See purchasing options here.
  • Textbook: Principles & Practice of Physics, 1st edition by Mazur
    • See purchasing options here.

Getting started

  • Connect to the online homework system using the instructions found here.
  • Information on connecting to the Pivot software will be posted here soon.
  • Slack will be the primary space where you can communicate with your peers and your TA.
    • Use your UW email to join our Slack workspace.
    • Get Slack running on your device. Here are useful tips and features for using Slack. We highly recommend downloading the mobile or desktop app, and turning notifications on so that you don't miss messages from your TA and other members in your tutorial section.

Class components

This class consists of lecture, lab, tutorial and exam components.  You can see all the components required in a given week in Modules.

Important Note: Since each exam includes questions based on the lectures, labs, and tutorials, missing a lecture, lab, or tutorial section can have an impact on your exam performance.  You should be sure to watch all lectures, and work through any lab or tutorial that you miss as soon as possible to minimize the impact on your course grade.

Lecture components:

Before each scheduled lecture you need to complete the assigned reading (see schedule below).  The lectures include the following graded components:

  • Pre-lecture Reading Quizzes (4% of grade):
    • For each lecture, there is an associated reading quiz that will be posted on MyLab and Mastering. Each reading quiz is due by 11:59 pm on the day of the scheduled lecture.
    • You have 5 attempts per question, with no penalty for each incorrect attempt.
  • Lecture video engagement (4% of grade):
    • After completing the reading quiz, you need to watch the lecture video and complete the embedded quizzes before 11:59 pm on the day of the assigned reading.
    • These will be graded based on engagement, not on correctness.
    • Your lowest three video quizzes will be dropped.  If you miss more than three due to a valid reason (family and medical emergency etc.), please contact us.
  • Lecture homework (8% of grade):
    • These will be due on Tuesdays at 11:59 pm, and will be based on material covered in the previous weeks reading and video.
    • You can access the lecture homework in MyLab and Mastering.
    • You have 5 attempts per question.
    • For multiple choice, multiple select and true/false questions, a deduction of 100% / (#options - 1) is given for each incorrect attempt. For example, if a question has five choices, for each incorrect attempt, 25% of the points assigned to the question is deducted. There is no deduction for questions in which you need to enter a value but you have a total of 5 attempts.
    • For late submissions, 20% of the grade is deducted for every day past the deadline.

Lab components:

  • Labs (12% of grade):
    • There are eight graded lab assignments, some of which may have multiple parts.
    • Each lab assignment under "Assignments" tells you the parts to be completed in Pivot.
    • The labs are due Wednesday at 11:59 pm.  Before then you need to collect and analyze data from video experiments on Pivot and answer questions based on your work.
      • After you start any of the assignments, you can save your work and go back to it as many times as you want before the deadline, thus, allowing you to talk to peers or a TA, and then go back and finish.
    • Each lab assignment will be graded based on the following:
      • Meeting learning objectives (3 points): Questions in the lab are answered, and the answers clearly show mastery of the learning objectives of the lab.
      • Needs some improvement (2 points): Questions in the lab are answered, but some answers indicate a lack of mastery of the learning objectives of the lab.
      • Needs significant improvement (1 point): Many questions in the lab are not answered and/or indicate significant lack of mastery of the learning objectives of the lab.
      • Not completed (0 points): Significant portion of the lab is not completed.
    • If you receive 0 points, 1 point, or 2 points, you can do or redo up to 2 labs without asking for permission.  After the deadline, you will temporarily no longer be able to submit new work.  Contact your TA and they can allow you to submit late work.
    • You will get a grade of 0 for the entire course if you receive less than 16 out of the 24 points possible on the lab assignments.
    • If you need to make-up more than 2 labs due to a valid reason (family and medical emergency etc.), contact us.

Tutorials components:

The tutorials include the following graded components:

  • Tutorial pretest (1% of grade):
    • These are designed to get you thinking about your ideas on topics covered in this course.  They are graded based on a thoughtful attempt, not on correctness.
    • These become available Friday at 3:30 PM and are due on Sunday at 11:59 pm.
    • Once you start a pretest, you will have 15 minutes to complete it without the ability to pause.
    • Your lowest tutorial pretest score will be automatically dropped.
    • If you miss more than one tutorial pretest due to a valid reason (family and medical emergency etc.), please contact us.
  • Tutorial in-class (3% of grade):
    • You need to attend and actively participate in discussion at your tutorial section (QZ section on time schedule) each week to get participation credit.  Each tutorial will be graded based on the following:
      • Adequate (2 points): Actively engaged in discussion throughout tutorial.
      • Needs improvement (1 point):  Multiple periods not engaged in discussion during tutorial.
      • Missing (0 points): Did not attend any tutorial section.
    • If you cannot attend your tutorial section in a given week, you can attend another section.  A schedule of tutorials with their Zoom links can be found here (select "12x" then select "121 Tutorial Schedule").  Be sure to contact your TA to let them know.
    • Your lowest tutorial in-class score will be automatically dropped.  However, you are still responsible for submitting the associated tutorial homework on time.
    • If you miss more than one tutorial in-class due to a valid reason (family and medical emergency etc.), please contact us.   
  • Tutorial homework (8% of grade):
    • Each tutorial has homework that is due at 11:59 pm the Monday after you have worked through the tutorial.
    • For each homework, you need to upload a scanned pdf file to the Canvas tutorial homework assignment. For instruction on how to create and upload a pdf, see the Tutorial Information.
    • Only part of the tutorial homework is graded completely (8 pts); the rest is examined for completeness (2 pts).
    • If you submit your tutorial homework after it is due, there is a penalty of 1% deduction of the score for every hour that it is late.
    • If you need to submit tutorial homework late due to a valid reason (family and medical emergency etc.), please contact us.
    • Your lowest tutorial homework score will be automatically dropped.

All important tutorial information can be found under the Tutorial Information.  Once at the tutorial website select "12x" for information general to all courses in the Phys 121-122-123 sequence.  Select the link for section A, B or C under "PHYS 121" to get the schedule for all assignments specific to your class.


Exams will be done online.  The exam procedure is described here.

The following dates are preliminary and may change.

  • Midterm exam 1 on Tuesday July 13th starting between 10:45 and 10:55 am (PDT). If you start the exam between these times, you will have the full 90 minutes to complete it.
  • Midterm exam 2 on Tuesday August 3rd starting between 10:45 and 10:55 am (PDT). If you start the exam between these times, you will have the full 90 minutes to complete it.
  • Final exam on Thursday August 19th starting between 10:45 and 10:55 am (PDT). If you start the exam between these times, you will have the full 90 minutes to complete it.


Note that there are no make-up exams.  So, students with outside professional, service, or career commitments (i.e. military service, ROTC, professional conference presentation, NCAA sports, etc.) conflicting with the exam dates must contact us early in the quarter to establish alternate examination procedures.  Exam scores for students who miss an exam without making prior arrangements will be zero.

Each exam is out of 100 points, and have three components:

  • 70 points on lecture material
  • 15 points on tutorial material
  • 15 points on lab material

Exams will count for 60% of your grade.  Your overall exam score will be based on the best of the following two methods:

  • Method 1: 20% from each of your midterms scores and 20% from your final exam score
  • Method 2: 30% from your best midterm score and 30% from your final exam score

We will design the exams such that a student who understands some of the material very well but needs some improvement in the remaining material should get a score around 65%.  If the class average on a given exam is less than 65%, then all the scores for that exam will be adjusted upward so that the average is 65%. Scores will not be adjusted downward even if the class average is higher than 65%.

If a student is found responsible for misconduct during an exam, a score of zero will be given for that exam for this student.  If the misconduct occurs during a midterm, only Method 1 is used to calculate the final grade, and Method 2 is not used.


You will get a grade of 0 for the entire course if you receive less than 18 out of the 27 points possible on the lab assignments.

Otherwise your final weighted percentage is converted to a grade point using the following thresholds.

grade point course score   grade point course score   grade point course score   grade point course score
4.0 92.0 3.0 76.0 2.0 60.0 1.0 44.0
3.9 90.4 2.9 74.4 1.9 58.4 0.9 42.4
3.8 88.8 2.8 72.8 1.8 56.8 0.8 40.8
3.7 87.2 2.7 71.2 1.7 55.2 0.7 39.2
3.6 85.6 2.6 69.6 1.6 53.6    
3.5 84.0 2.5 68.0 1.5 52.0    
3.4 82.4 2.4 66.4 1.4 50.4    
3.3 80.8 2.3 64.8 1.3 48.8    
3.2 79.2 2.2 63.2 1.2 47.2    
3.1 77.6 2.1 61.6 1.1 45.6  

Reading schedule

**The timing of the reading & lecture topics will likely be adjusted as the quarter goes on. The schedule listed in the following table is only approximate. Use the Assignments tab for the official due dates.

Week Day Date Reading** Topic** Tutorial Lab
Mon Jun 21 1.5, 1.6, 2.1 Lec 1: Intro/Foundations Watch the Tutorial Introduction video Lab 1:  Intro - Hill Runner (feat. Jessie Diggins)
Tue Jun 22 2.2–2.4 Lec 2: 1D motion
Wed Jun 23 2.5–2.7 Lec 3: 1D motion
Thu Jun 24 2.8–3.2 Lec 4: Change in velocity
Fri Jun 25 3.3–3.5 Lec 5: Constant acceleration
Mon Jun 28 3.6–3.8 Lec 6: Constant & non-constant acceleration Tutorial 1: Acceleration in One Dimension Lab 2-1:  An Introduction to Studying Motion: The Ping-Pong Ball Bazooka and Lab 2-2:  Motion Graphing a Dry Ice Puck on a Ramp
Tue Jun 29 4.1–4.3 Lec 7: Inertia
Wed Jun 30 4.4–4.6 Lec 8: Systems & momentum
Thu Jul 1 4.7–4.8 Lec 9: Conservation of momentum
Fri Jul 2 5.1–5.2 Lec 10: Kinetic energy
Mon Jul 5 No classes — Observed Independence Day Tutorial 2: Systems and Momentum  Lab 3-1: Blowdart Cart Collision and Lab 3-2: Boy on a Surfboard 
Tue Jul 6 5.3–5.5 Lec 11: Elastic collisions
Wed Jul 7 5.6–5.8 Lec 12: Conservation of energy
Thu Jul 8 6.1–6.3 Lec 13: Inertial reference frame
Fri Jul 9 6.4–6.5 Lec 14: Galilean relativity
Mon Jul 12 6.6–6.8 Lec 15: Center of mass Tutorial 3: Kinetic and Internal Energy Lab 4-1: Mathematical Modeling: Height vs Velocity for a Puck on a Ramp and Lab 4-2:  Toy Car Investigation
Tue Jul 13 Midterm 1 @ 10:50 AM
Wed Jul 14 7.1–7.4 Lec 16: Coherent & incoherent energy
Thu Jul 15 7.5–7.7 Lec 17: Fundamentals of interactions
Fri Jul 16 7.8–7.10 Lec 18: Energy & interactions
Mon Jul 19 8.1–8.2 Lec 19: Momentum & forces Tutorial 4: Forces and Newton's Laws Lab 5-1:  Force and Motion During a Hockey Slapshot and Lab 5-2:  Spring Force
Tue Jul 20 8.3–8.6 Lec 20: Free-body diagrams
Wed Jul 21 8.7–8.9 Lec 21: Equation of motion
Thu Jul 22 8.10–8.12 Lec 22: Impulse & systems
Fri Jul 23 9.1–9.4 Lec 23: Work and systems
Mon Jul 26 9.5–9.6 Lec 24: Calculating work Tutorial 5: Work and Conservation of Energy Lab 6-1: Energy Conservation for a Spring and a Cart and Lab 6-2:  Forces on Objects on a Ramp
Tue Jul 27 9.7–9.8 Lec 25: Power
Wed Jul 28 10.1–10.3 Lec 26: 2D motion
Thu Jul 29 10.4–10.6 Lec 27: Vector algebra
Fri Jul 30 10.7–10.8 Lec 28: Projectiles
Mon Aug 2 10.9–10.10 Lec 29: Friction Tutorial 6: Motion in Two Dimensions Lab 7:  Friction: sliding on an inclined plane
Tue Aug 3 Midterm 2 @ 10:50 AM
Wed Aug 4 11.1–11.2 Lec 30: Circular motion
Thu Aug 5 11.3–11.4 Lec 31: Rotational kinematics
Fri Aug 6 11.5–11.6 Lec 32: Angular momentum
Mon Aug 9 12.1–12.3 Lec 33: Torque Tutorial 7: Dynamics of Rigid Bodies Lab 8: Rotational collision:  Dart collides with wooden stick (due on Mon)
Tue Aug 10 12.4–12.5 Lec 34: Conservation of angular momentum
Wed Aug 11 12.6–12.7 Lec 35: Rolling motion
Thu Aug 12 12.8 Lec 36: Rotating vectors
Fri Aug 13 13.1–13.3 Lec 37: Gravity and weight
Mon Aug 16 13.4–13.5 Lec 38: Equivalence and force
Tue Aug 17 13.6–13.7 Lec 39: Gravitational potential energy
Wed Aug 18 N/A Extra office hours
Thu Aug 19 Final Exam @ 10:50 AM
Fri Aug 20 Done!



Research Study Information

This course is part of a research project  examining student reasoning ability and attitudes about physics with the goal of  improving physics teaching.  By enrolling in this course you are automatically included in the study. Early in the quarter, students will have an opportunity to learn about the study and to remove themselves from the study if they wish. Your instructor will not know whether or not you participate. Later in the quarter, this link will become active and allow you to review the details of the study, contact a member of the research team, or remove yourself from the study.

Access and accommodation

Your experience in this class is important to us, so if you have a temporary health condition or permanent disability that requires accommodations (conditions include but are not limited to: mental health, attention-related, learning, vision, hearing, physical), please contact DRS to arrange accommodations.

Safe campus

We are committed to ensuring a safe environment on campus.  We encourage you to check out the resources available here.

Religious Accommodations

Washington state law requires that UW develop a policy for accommodation of student absences or significant hardship due to reasons of faith or conscience, or for organized religious activities. The UW’s policy, including more information about how to request an accommodation, is available at Religious Accommodations Policy ( Accommodations must be requested within the first two weeks of this course using the Religious Accommodations Request form (

Academic integrity and student conduct

The University takes academic integrity and student conduct very seriously.  Behaving with integrity and respect is part of our responsibility to our shared learning community.  Acts of academic misconduct may include, but are not limited to, cheating by working with others or sharing answers on exams.

Please note that screenshots or recordings of instructors, other students, and course materials during active video (Zoom) participation sessions are strictly forbidden.  Streaming or posting inappropriate materials on any course platform is also not allowed. 

All the course materials including exam and quiz questions, lecture notes, lecture videos are intellectual properties of the instructor and the University of Washington. Distributing them in any form without permission is forbidden.  

The University of Washington Student Conduct Code (WAC 478-121) defines prohibited academic and behavioral conduct and describes how the University holds students accountable as they pursue their academic goals.  Allegations of misconduct by students may be referred to the appropriate campus office for investigation and resolution.  More information can be found online at

If you’re uncertain about if something is academic or behavioral misconduct, ask us.  we are willing to discuss questions you might have.

Catalog Description: 
Basic principles of mechanics and experiments in mechanics for physical science and engineering majors. Lecture tutorial and lab components must all be taken to receive credit. Maximum 5 credits allowed for any combination of PHYS 114, PHYS 117, PHYS 121, and PHYS 141. Prerequisite: either MATH 124 or MATH 134, which may be taken concurrently. Offered: AWSpS.
GE Requirements: 
Natural Sciences (NSc)
Quantitative and Symbolic Reasoning (QSR)
Section Type: 
Last updated: 
August 16, 2021 - 4:23pm