i need a decompose the vector video where I show first someone walking a displacement, then I show someone pulling a sled.

***************Below is from Winter 2020********************

Write 4.8 to go with big picture rotation, continuation of 1.8 and 2.8 to include rotation.

I need to make a friction video explaining what friction is and what the coefficient of friction is… and what the limits are. AND I need to make the dragster video longer and slower, and maybe provide more comments. Maybe add a problem in the text calculating the necessary coefficient of friction for 0-60 in less than 2 s…. advertised Tesla Roadster.

Short Survey #1 deals with a “low friction” sled… but it’s not no friction. This screws things up. I need to take this into space, with really no friction.

Consider adding this statement to the syllabus:

I wanted to begin by profusely thanking you for this “lens” teaching style, But I won’t lie it took awhile to get used to. In The first few weeks I felt like I was learning stuff I already knew but with this “lens” bullcrap, however I’d say about 2 weeks ago it finally hit me how incredibly useful this mindset was when you start getting into more complicated problems. I think I first saw this when you showed us why we never would need to use the 2 main kinematics equations. And truthfully these two equations I worshiped at the start of the quarter I don’t think i ever will use again. So to that, I say thank you for the lessons you taught me, and sorry for my reluctance at first to embrace your teaching style.

Section in text about the value of “centrifugal force”, and “centripetal force” and how we can compassionately respond to people using these terms and try to understand what they are trying to say and how to interpret it.

Don’t have assessments be more than 20 minutes. It just seems like an inordinate amount of class time.

Rewrite text:

Provide small spaces after examples for students to work them.

Rewrite 1.8, 2.8 and force discussion…. and a 5.8

Fist class: Appropriate Video Watching… write something in the text about it.

For first assessment, form a scaffold for picture and lens and motivation.

We need to have the project #2 proposal due a week earlier so they have more time to do it.

We need a chapter 4.8: applying the full rotation lenses, Probably a chapter 6.8 for applying systems, and maybe something in chapter 7 too for angles.

We should move more in a parallel direction: We should move many interesting problems such as the painter connected to the pulley and the block and tackle to chapter “8” that employs everything we’ve learned and thereby revisits the material… in the “spiral” method.

add “advice to future students” to the course surveys. I could give this information to future students along with outside time required for this class.

End of week 4: separate moment of inertia video into two and move integration into next day (next week). Make a Force, Torque, Power video.

A truck and car collide. The drivers have the same mass. How do the forces on them compare? This was already added to the survey.

I got this link from Joy with study tips: https://www.mydegreeguide.com/how-to-study-tips/

From Student Evals, 121 W2019:

If I had to give any suggestions for improving the class, I would recommend creating a trig review video for comparing triangles and their correlating angles. Learning about vector diagrams and 2D components was a bit overwhelming for me when it came to incorporating trig. But I feel like if I had a review video of this material, I would feel more confident with creating vector diagrams.

Students need to do a better job with their drawings, especially if they don’t use trig!

“There are no outside forces/torques.” I have to address this more explicitly in class over and over again.

A student told me today that she watched the precession video again after the activity and thereby came to understand the concept much better. She thinks that I should assign the video twice.

I need a video on how to use the quadratic displacement equation for a rock thrown upwards, and then I need a video to solve the parabolic projectile problem.

If I make a countersteering video. I can use these videos: (5:47, https://www.youtube.com/watch?v=ljywO-B_yew pushing with one finger), (2:35 https://www.youtube.com/watch?v=upAI5rb_pFY bicycling), (4:47 at https://www.youtube.com/watch?v=iIaUQPASi9c motorcycle racing).

I dropped the following from the winter 121 curriculum:

- Please Watch Universal Gravitational Potential Energy
- Please read 5.4 Gravitational Potential Wells, and Escape Speed that you can find in our textbook.
- Please Watch Universal Potential Energy Graph. this is short and I think you’ll like it.

I failed to act on the following message to myself, so this still needs to be done.

- Centripetal Force Video should be cut into 3… and I need to change it so that it is appropriate for the class now. I can use omega in the formula, and I shouldn’t use the 2D yet.

Week 5 Thursday, W19, I need to break this into two classes. This is too much material in too short a time… rolling objects uphill, angular momentum, AND statics.

I deleted the following from the 121 W19 class at the end of week 5:

we will examine an object that circulates into a circular path… like how the moon doesn’t travel in a straight line because the attractive force of gravity between the earth pulls the moon into a circular path.

**Thursday**

__Conserving Angular Momentum, when Sum of the Torque = zero__

**Before Class**

**In Class:**

Revisiting the “inertia wand”

Dropping kids on merry-go-round, barbell spinning in space.

Ignore below this line***************

- The Coriolis Effect video needs to be fixed. I need to voice it over or drop it completely. Students find it confusing.
- If we look at the earth spinning in space, we might notice that there’s nothing making it turn… that it is free of external torques. We might consider that we’d then look at the earth through the lens of
*angular momentum.*What could we learn? Please see video on Coriolis Effect made by students from Fall, 2014. Look for a number of things:- Do we understand the Coriolis Effect?
- Do we see the value in looking through the angular momentum lens?
- Are we getting ideas for how we’d like to make our final video project?

****************end of deleted material**********

- I need to break the moment of inertia video into three videos: defining, multiple masses, solid bodies. – each 4-5 minutes

Put the diversity statement in the syllabus video. And maybe add people who just want to pass the class. “My commitment is to serve you regardless of who you are and how “good” you are in physics. If you just want to pass, I am committed to support you to do that and make it as enjoyable as possible.”

**Diversity, Inclusivity, Sustainability:** Cal Poly’s mission statement includes “…Cal Poly values free inquiry, cultural and intellectual diversity, mutual respect, civic engagement, and social and environmental responsibility.” Diversity, inclusivity, and environmental responsibility have recently taken on great importance, globally as well as at Cal Poly. As an instructor, I wish to nurture awareness of how our actions affect others, near and far. I strive to maintain a classroom environment in which meaningful dialogue and debate is encouraged. I welcome individuals of all ages, backgrounds, beliefs, ethnicities, sexual orientations, gender identities, national origins, religious affiliations, abilities—and any other visible and non-visible differences. In any decision-making process, we will remind ourselves that our knowledge is not complete and that we can benefit from other perspectives that contrast our own. I believe that good problem solving is inclusive, requiring application of empathy, critical thinking, and ethics to all aspects of the problem-solving process. Lastly, I think it’s our responsibility to make the world a happier place – all of us, all the time.

- I deleted the The Ballistics Pendulum video…. has at least two math mistakes in it. I should drop out this video from the curriculum. It doesn’t help the students because they didn’t even get the concepts because I’m all over the place. I could make a new one that is simpler and with no math.
- Solutions for PS#2 sliding down a curved ramp question. I also go over some calculus that may be interesting here. This is from a past class, so the numbers are different.

For momentum lens and angular momentum lens, the reason is NOT “there is no outside forces.” I need to change that in the text and in my narrative.

~~Students do not identify “torque = dL/dt” for precession. I need to put something in the text and maybe have another exercise in class…~~ **maybe for linear momentum too?**

Difficulty with conical pendulum. Need exercise in class on estimating speeds, normal forces.

Making Stress your friend. Before the first MT

I need to add a part to the text about what conservation is and isn’t!!

2D momentum video at the end of the quarter is confusing because of wrong numbers. Fix it or dump it.

If I make a countersteering video. I can use these videos: (5:47, https://www.youtube.com/watch?v=ljywO-B_yew pushing with one finger), (2:35 https://www.youtube.com/watch?v=upAI5rb_pFY bicycling), (4:47 at https://www.youtube.com/watch?v=iIaUQPASi9c motorcycle racing).

The toy car video is really good, and maybe should be shown sooner with springs as an example of what the second project can be.

Make a better Trebuchet video for final week, by merging our two videos.

Change the gyroscopic stabilization videos to rotate about the axis from rotate “left to right”

Move each of the gyroscopic stabilization videos to one day earlier.

Possibly check slack lining video. Does it get confusing near the end?

The Statics Video should be simplified. We don’t need something this difficult… it would be better to just redesign the diving board problem.

My “which way does the wheel turn when I pull the string” lecture should be greatly shortened so I could get on with other things.

Parallel Axis video needs to be looked at. See message from Harry about student comments.

I should add the video about estimating the speed of rockets to the 141 curriculum.

I could make a video for center of mass.

#1 Spring Energy Conversion video from the Midterms corrections. This has been moved to week 10 for 141. However, it should be part of the review before MT#1.

Centripetal Force Video should be cut into 3… and I need to change it so that it is appropriate for the class now. I can use omega in the formula, and I shouldn’t use the 2D yet.

The Coriolis Effect video needs to be fixed. I need to voice it over or drop it completely. Students find it confusing.

I need to make a new video for the “Torque and the Lever Arm.” or just delete it. I an also look at the diving board problem as to if I want to change something.

I need to break the moment of inertia video into three videos: defining, multiple masses, solid bodies. – each 4-5 minutes

The Ballistics Pendulum video has at least two math mistakes in it. I should drop out this video from the curriculum. It doesn’t help the students because they didn’t even get the concepts because I’m all over the place. I could make a new one that is simpler and with no math.

There’s a mistake in the *springs!* video. I should fix this.

I should rework the students’ ballistics Pendulum video.

We should end the vectors and momentum video at 11:45 because we don’t need the second dimension.

If students do poorly on a test, let them have a week to prepare for a retest. While students work problems, I should be doing “a lap” to see each group.

Below from Winter 2018

I made solutions for MT#1, Winter 2018. I could present them to students before MT#1, ( Question 1, Question 2, Question 3, Question 4 ), but I already have solutions for Fall 2017.

I should make a study guide for each exam including the big exams

I think I need an Energy(initial) = Energy(final) in the energy chapter… for protocol.

In text, I need to add a section about adding vectors in 2D. I did that in chapter 2.4 with the last three exercises, and then in 3.0 with an extra exercise, I can add it in chpater 5 (when I do that), and 7.0?

Angular momentum of a point mass video is ineffective. I should make another one. Also, students are confusing angular momentum with momentum. Students think that momentum can be converted to angular momentum. They also mix them up with each other in calculations. Also they leave out the “angular” in their lens identification. This should definitely be inserted into the text.

On survey monkey, I should move the “hitting the tennis ball” problem from the same section as “throwing the ball upward” as they both deal with an imaginary residual force.

Students didn’t appreciate explicit solution videos for the midterm. I should not do them any more.

In studying for MT #1, I should introduce just one midterm per day. The last should be spring 2017 because I have videos for the solutions.

I should introduce the concept of *relative* motion in the first chapter on kinematics.

I should work into the video somehow on potential energy diagrams that the zero is arbitrary.

OMG… what a train wreck the ballistics pendulum problem was on PS #3. Students were so bewildered… I have to start with a simpler one (no spring constant question), and I should make a video for it highlighting the need for two lenses – I should do this for class #4 – using the four lenses and add the problem to 1.8. It never occurred to most students that using two lenses was ever necessary.

PS#1 could use some simplification. I should reduce the complexity in the “falling off the cliff”… I should look at the solution set to see what students are seeing and thinking.

Move the rocket video from week two to week One.

Below from Fall 2017

Drop last question from last survey (5th) about chair sitting on the ground. Done

Move boat stabilization video to day after precession. Done

Move the centripetal acceleration / playground carousel video to earlier in the quarter when we do centripetal acceleration. Done

For the Big Exam question of the girl running at the carousel, I should simply the math, provide the moment of inertia of the disk? Done

I should have the first 10-question survey before MT#2. Done

What force pushes the mass off the turntable? Should be the first question we ask. Done

In the “which way does the bike accelerate?” problem, I should start with, “you are sitting on the bike” and discuss the problem. THEN, I can pull it from the outside.

I need to change the wording in the text and the video for dynamics… support statement should read, “I pick the dynamics lens because forces on a body are causing it to accelerate”.

Elon Musk just uses simple basic concepts: Quartz Media Story

I need a simple video as to why the scale reads my weight.

__Below is from Spring 2017__

I took this out of the text, so I should put it in the website or in the video or on the syllabus:

“Your responsibility in this class is to develop working relationships with other students. Our class is a social environment, and we will work together solving problems, arguing about concepts, studying for exams and doing projects. Many students enjoy office hours, because you can sit at a table together outside my office and call me over when you want to. Because I won’t always be there in front of you, you will need to work with your peers, and you will also need to take the initiative to say, “Pete, we have a question.” Lastly, you don’t need to wait until office hours to get together for study or group, and the working area outside my office is always there.”

From student evaluations:

I should have students switch groups.

I should make clearer that students should ask me questions during office hours. I really should be out there during office hours.

I should improve the videos – shorter, better, subtitles.

Take out the statement in the syllabus regarding half a letter grade of extra credit for the videos.

Dynamics Protocol: They HAVE to start with “vector sum of forces = ma… then identify forces and acceleration in a FBD, then show them adding.

**We need to have a Big Exam! every week that doesn’t have a midterm. I also need to provide the scaffolding for answering the questions correctly in the first and second week. Additionally, I may need to be more demanding on the first problem sets and homework.**

I have to be more vigilant about evaluating the projects. I think we should have projects due the end of week 2, 4, 6, 8. The end of week 8 should be the video, and students should not be allowed to delete any videos.

**First big exam and homework assignments need to spell out the process of lens identification, motivation, approach. There should be a quiz explicitly on each lens, the motivation, and the approach.**

For the first 2D momentum collision, I should start with qualitative questions like… what direction did the car go off? How do you know? If they sticked together, could they both have gone off in this direction? Why?

For the short conceptual exam questions, I should read through them and simplify the wording. Some of the wording is so confusing that it’s not the physics that’s being answered. In particular the sled on a hill. I also think I should make the pushing the sled problem more obviously frictionless.

Very important! – when we start components, no one understood how to do the “find the coefficient of friction” problem that I introduced. I need to start more gently with a frictionless inclined plane… for instance, if I put up the one end of the frictionless plane 1/11 the length, I could compare it to the level plane with a 1/10 ratio of masses on a string!

I should be mindful that physics students may not know that PHYS 141 is “introductory mechanics”.

I should take the numbers out of the curriculum all together for the first week or two and students can describe what they see with a narrative and draw pictures especially free body diagrams. In particular,

The bottle full of water should be moved forward to the first week, and the broken string should be moved back to week 5 or so.

From the start, I need to consistently refer to problems in the text for the problem sets.

__Below is from Fall 2016__

I should make HW problems easier or at least simpler.

Early on, I should have a midterm or BE question on like the elevator problem… multiple choice with explain. Is the tension =, <, >, mg, +/-.

In breaking the strings connected to the inertial ball, I should start by affirming what the students say, and then challenge them to find a way to break the top string:

1. In class, I was able to pull string connected to the ball differently, resulting in different outcomes. Using a FBD with the proper dynamics protocol, please explain the different ways I could break the different strings. I think that the last one is the easiest, so you might start with d) first and go backwards.

a) How did I make the string at the bottom break?

b) How did I make the string at the top break?

c) How did I make the string at the bottom break even if there was no string connected to the top?

d) How did I make the string at the top break even if there was no string connected to the bottom?

Build better motivate and apply lens in syllabus for grade.

Make a better “calculate the torque on the wheel” question where there is all the same forces and the students just rank them for strongest to smallest.

Recheck questions for 6.1 Rotational Systems

I should think about where I put the solving a system with forces video.

I think that when we do a day at the races, rolling or sliding things down the ramp, I should do it over a number of days. I should introduce the different objects one at a time.

**I need to redo the dynamics video. I get my x and y mixed up, I say “I’m going” all the time, and I have some glitches in the editing.**

**I need to make a new centripetal acceleration video… Or, I need to make 3 videos out of the present 12 minute video.**

**I need to make a new universal gravity, inverse square law video. It’s painfully slow to listen to.**

Below, comments are from 141 Spring 2016

Student evaluations were OK, but lower than I expected and lower than in Fall or Winter. I think that students don’t like being told what to do. I think evaluations will decrease with increased course requirements. In particular, instituting the grade decrease for not doing either project was a glorious marketing failure. Likely, the same is to be said for class participation… Likely, I should make this extra credit, because this is what it was in the end anyway. Grades were so low when the non-participation policy penalty was included, that I just raised everyone’s grades.

2-D momentum problems – good understanding here.

Precession: Even after one week dedicated to torque being the rate of change of angular momentum, students don’t distinguish angular momentum from torque: “There is some torque from the wheel spinning”.

Ratios and inverse square law, students are not doing well. We didn’t spend time reviewing them.

Students didn’t learn conical pendulum… so for MT#2, problem #2, there was like absolutely no retention. There needs to be a recognition in this problem of the *direction* of the acceleration and how the axis should be drawn. I think that this is the result of many system problems where we *automatically* decompose gravity into a parallel and perpendicular component. This __ must__ change. From now on, we need to consider when we do this, what is the preferred axis and why did we pick a parallel and perpendicular.

In the final exam, I introduced questions that didn’t ask for numerical answers. I think that this was a great idea. I will increase this and extend it to the midterms. In fact, maybe the first midterm should have almost no numerical answers.

The video projects lack confirmation: Students do a calculation such as what the speed is when they drop something. However, they often do not verify this speed by a direct measurement, so they simply assert at the end that either mass didn’t matter or that energy was conserved because they asserted it in the very process they used to calculate it.

Put a question in the Atwood machine about, “hey, this is the general formula for a system!”

Put a statement in the “syllabus” video about accessing the links from the webpage every day – not PlayPosit.

I should introduce during the elevator discussion: the idea of “how do I keep something in contact with a surface when it is upside down?”

it is amazing to me that students will *not* proceed with the dynamics protocol until they know how it’s going to turn out… or at least this is how it seems to me. I think I have to slow down and take them through it step by step when I introduce it. After a discussion with a student – who told me that they will *not* use the protocol because they just don’t imagine it helping them, even though they may *know* otherwise. This student suggested that I have some quizzes after the first video requiring it step by step:

Is this a dynamics lens – why?

What is the formula you know will work for dynamics?

Make a good drawing and/or Draw a FBD labeling only the forces

Is this in equilibrium? If not, what is the direction of acceleration?

Draw a sum of the forces diagram indicating where is the acceleration.

Use the dynamics formula to find the force (or acceleration).

We should adopt a grading rubric for the problem sets and class work that is roughly consistent with exams.

I should have the vectors force and momentum *before* the elevatory dynamics problem introducing “the protocol”

The videos on vectors should be changed. It seems a waste of time to introduce vectors in one dimension at all. I think next quarter we should do one dimension without vectors, then rotational motion without vectors, then do gravity, vectors, projectile motion, centripetal acceleration, and systems.

We will grade Big Exams and Problem Sets just as we presently grade in-class work: for participation only.

I need to decide about how what to do on days I collect problem sets: If I have new material on videos for these days, then it will distract students from finishing the problems. However, if I don’t have new material, then I will not have anything to work on during class… I think that this second point is more important. We’re supposed to do most of the problems in class anyway. (?)

I think that the videos are not an adequate way to introduce the material. It seems that students have no idea of how to handle rotational directions and in particular what precession is. I counter suggestion is to introduce the physical systems in class, *then* have students watch the videos, *then* have examples in class… The spiral method. For instance, I could have had the wheels with the students on the first day we did rotational motion. Then I could have had the video for precession, then we… I don’t know. For the “day at the races”, I will add a 1 minute video with the ppt. slides before the systems, so that students have an idea of what’s coming.

Separately, I need to edit the precession video because students have no idea what precession is… they really can’t see it from the video as it is either. So I need to have some questions asking precession is…., and I also need to improve the video. It may also be worth noting that a few other things came out… like when gravity pulls on a rock thrown horizontally, the force is the rate of change of linear momentum and it slowly adds momentum to the rock, changing it’s direction.

Below, comments are from 141 Winter 2016

We need to leave the computations out of some of the problems on a test – most of the problems on the first midterm and ~ half the problems on the second one.

I need to make a video to tell students about the syllabus and how they should learn. That videos are their lectures and they are responsible for learning the material.

For full credit on the project, there must be 3 or 4 people. 2 or 5 people are allowed in extreme situations if you consult me. For full credit, they should make appropriate use of units and significant figures.

We should try to give a few questions before the videos that a student should be able to answer after the video.

I should have an explicit statement on the syllabus that I do not use PolyLearn and what my philosophy is about PolyLearn.

For project, we should state that they need to actually do something novel, not just carry out a standard calculation. They should figure out a way to hold the camera motionless, not in someone’s hands, and the sound quality should be observed.

I should reassign grades next quarter so a D is achieved with addressing a lens, and a C is for a description of that lens onto the physical system in question.

In the __ system of masses__ using energy video, I give a system direction that I really shouldn’t. It’s not necessary.

I also think that I should start with Energy, which I do, but save the tug-o-war question until the second day of dynamics with systems.

Instead of making an extra long PS#4, I should have just collected #4 the Monday after MT#2 and made PS#5 the second half.

I need to reinforce “just see the page every day”. Maybe by putting it on the PPT for the first week?

I need to explain the elevator dynamics problem shorter and simpler in the video.

In the marble on roller coaster demo, I should ask the students to close their eyes and *watch* a simple race happen between just two marbles.

Below, comments are from 141 Fall 2015

I need to make another (different) video on torque, stability, and precession. I should also trim down the wheel kick video.

There should be a qualitative worksheet for trigonometry… like estimate the acceleration of the sled when the rope is pulled at different angles.

I need to make a concerted effort to bring the students to commit to an answer. I think otherwise, many students will simply watch the solutions in a “watching a movie” attitude without augmenting their understanding. For example, in the three Veritassium videos regarding a bullet hitting an object off center, I could have the students during class comment on what they think will happen. Also when we do “where do you weigh more?”, I should ask the students to consider this the night before. I should put it on a video or on the problem set. Also, in class, I need to find a way to get students to open a notebook during discussions.

In when we do gravity and satellite equation, I need a video on how to do ratios.

I will change the syllabus indicating that it is not enough to identify a lens to get a “C”. One must support this statement and/or outline how it will work. Also, I need to redefine how grades are “averaged”. For instance, if a student takes a test with four questions and doesn’t correctly identify the lens for two of them, then they should get a “D” on the exam because “C” means consistently identifies the lens and supports it. This needs to be more clearly stated in the syllabus.

Below, comments are from the mixed SUSTAIN class (waves, thermal, optics) of Spring 2015

April 16, 2015. Some interesting additions to the class and lab: 10 minutes of reflection in each group with a short report of what they are talking about. It is sometimes helpful to the group. For lab, I have dropped a lot of the “cookbook” protocol from the lab report, dropping about half the content. Then I am running around trying to Socratically asking questions to get everyone to do the lab right…. “right” is something I realize is my opinion, and that if I don’t do anything to help them, they all do the lab differently, and explore something interesting. Yesterday in lab, we spent 10 minutes visiting other peoples’ tables to explore what they were doing differently. Students indicated this was a positive experience. Also, I took some time to talk to a few students who wanted to have the wave function explained… we explored it slowly in an exploratory way, although I spoke and they listened. I presumed they knew nothing and I asked only some simple questions.

Today, I explained the two slit experiment although it felt rough, and that few understood me. 28% of the students had watched the video. I think very few had done the reading. When I think about the differences between yesterday’s “successful” explanation, and today’s “unsuccessful” explanation, this is what I might learn:

1. Yesterday, the students had struggled with something for a while before I explained it to them. We had done some questions in class and on practice exams.

2. When I explained it today, my intention was to get it done. Yesterday, my intention was to communicate and explore with them. I was more patient yesterday.

3. Yesterday, only the students who didn’t understand were watching. Today it was the whole class.

4. When I explain something, I could draw explicitly on material from our resources. For instance, my explanation centered around a diagram that exists as a figure in the text. I should have taken this text and caption from the book, so I’m inherently referring students to their text. I think it’s important that I have contingency for people who don’t understand… that I can refer to some resource.

5. I pointed out that few students watched the video. I think that doing so has an adverse effect on the moral. If I am not going to grade on watching videos, I don’t know if I should teach as though people did.

May 27 – Lab. Students are retaking the second midterm because the first go around didn’t go well. As a result, very little new material was studied in the 2 weeks between the midterm and retake. I think that there needs to be a better way to do this. MT#1 had a better model – students approached me when they were ready to retake the material and I provided them with another question. Another option would be to just have the final exam replace questions they didn’t get right.

June 3

There’s a CPE Professor, Clinton Staley teaching with a flipped classroom: http://users.csc.calpoly.edu/~kmammen/357/

He provides transcripts (notes) and another resource like mastering physics. This may be a good idea. I met with a student from Fall who didn’t benefit from the way I invoked the flipped classroom teaching style. However, he also recognizes that if he *had* convinced himself that this would work well for him, it would have. He said that if he had been invested in it, it would have worked. I asked him to write a statement to give students so that they will opt out of the class if they think it won’t work for them, and to encourage them to have a different mindset if they are “stuck” in the class.

Below, comments are from the mixed SUSTAIN class (mechanics) of Winter 2015

0) I should have the elevator cable pulling downward for one elevator example.

1) I should have a simple ballistics pendulum problem in week 2 problem set.

2) Trouble with Tracker again – I assigned a simple way to graph the grasshopper without using tracker.

Tracker and kinematics. I should have the grasshopper assignment the week before the personal kinematics assignment. Now that I have shown how to do the grasshopper video with just a ruler, then we should be able to do it at the end of the first week, and then go out to the track on the second week. I should provide my Excel file as a resource for doing the tracker assignment.

Videos:

1) I need to repost the pushing the box problem in week 2. It has a black spot at ~4:30 and in general can be improved.

2) I derive the proof for gravitational potential energy twice: in the dedicated video as well as in the video on forces and energy.

We would do better to keep things in one dimension (no vectors) until after the first midterm. The midterm would cover energy diagrams and springs.

When we introduce 2D vectors, such as inclined plane (after midterm #1), we should do it without trigonometry, but rather by visually inspecting the size of the vectors and angles. We can add trigonometry the next week or so. This will get rid of the perceived requirement of a calculator.

Improve the slackliner video. Remove the reference to it being a spring.

Before the Veyron problem, provide a video about changing units for energy from kWh to Joules… or just provide some additional guidance. Or provide website.

The fire hose / coal protester problem should be during the second week when we do the big picture of mechanics.

I should break up the rotational videos to have smaller amount of material in them. Then I could introduce the topics one at a time.

I should make a video on Centrifugal Force.

For my demonstration of torque, I should get a model of the human arm to show how you get no torque on a straight arm.

When I switch to rotational motion, it may be a good idea to spend a day on identification of lenses without getting involved with the actual computation… maybe not.

It may be a good idea to introduce rotational coordinates and centripetal acceleration earlier, like after MT 1, before systems of masses and pulleys. The extra time for another iteration may improve students’ understanding. I need to write a simple circular dynamics problem for them with three scenarios: I’m at the top of the loop with speed v, bottom of the loop, and top of the loop on top, so they can practice writing the vector sum of the forces = ma. Also, I should put one of these on a “big exam”.

In general, I should provide more short questions. Also, In order to get a “C”, students must identify the concept and take one additional step. So for instance, if they identify “statics” they must have sum of the forces = sum of the torques = zero. Otherwise, they get a C-

Below, comments are from the two 141 classes of Fall 2014

Students still default to the kinematic equations, even if I haven’t taught them. They also receive help from each other or tutors that use them. In the future, students will lose credit for using formulas that I haven’t introduced in class. Additionally, rather than expect the students to pick the conceptual approach that I want, I should guide them to it: “explain why energy conservation is the best way to solve this problem.”

The tracker and the car problem on the first problem set were kind of challenging. I may want to not do them in the future, or at least provide for more support that tracker may not work.

“no calculators” should be extra credit – on problem sets and on exams.

I’m not sure it was a good idea to introduce trig in the beginning of week 3. It might be a better idea to keep things one dimensional until MT1, and then introduce components and trig. I could add friction instead. It would simplify the FBD. The first three weeks could contain energy diagrams and force = – gradient of potential energy.

Should students read section 7.9 (world energy use) in the first week of class? I think so

The syllabus states that I will provide MT answers and also a week for the students to do the problems and hand them back. I shortened this time to 1 day and didn’t provide answers. When I realized that this was contrary to the syllabus, I changed it, but in the future, I have to comply with the syllabus, so I need to decide if i should change the syllabus or go with the answers and longer time. I think the latter may be better, as student tension is high after an exam as it is.

I think that the fire hose momentum problem could have been in the first week with more guidance.

**Problems with the Text**:

Acknowledges the existence of “centripetal force”

Uses the term “escape velocity” to incorrectly refer to the orbital velocity.

Section 3.5 nicely discusses relative velocity. I just taught this by making it a problem in PS #3. I should have recommended that students read this section at least with the problem set.

I’m considering having two tiers of questions on a problem set: 1 tier for students who are seeking an “A”, and another tier for everyone else. I think that this would likely take some of the pressure off those that are struggling to understand basic concepts and can feel overwhelmed by the problems that are meant to challenge students who have already mastered the concepts and find the challenge exciting.

Deleted from the websites, but not irrelevant.

__Post this before the first midterm. This is the TED talk I referred to in class today about how body language affects your performance.__ Body Language TED talk__. Please see it if you like. I find it informative and entertaining.__

In solving systems of masses, it seems some students don’t get that tension is an internal force and therefore can’t be found by looking at the system as a whole. Maybe I should start more systematically in deriving the system of masses by *first* using the dynamics of each mass simultaneous equations and *then* show them how to do it as a system.

Even after the second midterm, some students are leaving answers in fractional or radical form expecting to get extra credit for not using a calculator. I need to state more explicitly that answers must be in decimal form, and without a calculator, these answers need to be estimated. I could also recommend that they memorize few numbers such as sin of 30, 45, 60 as well as the angles 53 degrees and 37 degrees for a 3-4-5 right triangle.

We need a quiz in week 1 defining each of the 4 concepts, providing an example, and stating how you know it is one of these.

I wonder if I should use this Veritassium video at the beginning of class:

https://www.youtube.com/watch?v=AcX3IW00nuk

The SuperQuiz 3 is not looking good. I’m thinking that students may benefit better from daily challenges in groups that solve short problems. These problems can be collected, and we can go over them each day. This was the protocol that worked so well in fall 2012.

Even the last week of class, on the last quiz, probably less than half the students started a problem by identifying a concept. I think that I need to have a few quizzes in the first and second week requiring students to identify the concept at play. Then, I should continue to require this identification. In short, I need to set up a stronger structure for students to initially identify concepts. At 18 years old, most students have many years of conditioning that has them immediately seek a formula. The 1:00 PM class is much more restless/energetic than the 10 AM class (exams at the same time), asking many 4 times as many questions for clarification and visiting the restroom 4 times as often. They ate fewer bagels and more cream cheese. two cream cheeses is not quite enough for one class.

Also it would be a lot easier if students would put their name in the upper right hand corner of every page that is theirs.

Final Exam:

1) Students did stupendously well on kinematics and dynamics! Interesting because we spent less time on this part of the curriculum than ever before.

2) Students sometimes start a rotational dynamics with a formula: F = mr(alpha), by making the substitution of tangential acceleration = alpha*r. This would only work for a pt. mass at some radius r. The rotational dynamics formula to start with is Torque = I*alpha.

3) Students are not manifesting an understanding of what happens when you change the moment of inertia to a rotating, falling object. I think that the video that the yo-yo group did would have been very helpful if it had not been so poorly executed.

4) Students are failing to distinguish momentum from angular momentum