Flappy Bird Physics Is Real Life?

via Today’s iPhone

If you don’t already know, Flappy Bird is the hot new mobile game right now. The premise is simple: navigate the bird through the gaps between the green pipes. Tapping the screen gives a slight upward impulse to the bird. Stop tapping and the bird plummets to the ground. Timing and reflexes are the key to Flappy Bird success.

This game is HARD. It took me at least 10 minutes before I even made it past the first pair of pipes. And it’s not just me who finds the game difficult. Other folks have taken to Twitter to complain about Flappy Bird. They say the game is so difficult, that the physics must be WRONG.

Somewhere Mr Bourne is telling some kid that the physics on Flappy Bird is all wrong

— Rohil Prathap (@RoPrathap56) January 30, 2014

Flappy bird doesn't obey any laws of physics!!

— kubobubo (@VaclavekJakub) January 30, 2014

Flappy Bird, the game where you think the physics in it are just plain trolling with ya T.T

— アキラー (@NurulAkiller) January 30, 2014

I swear to god, the physics of flappy bird doesn't make sense at all!

— Mads Elton Nilsen (@MadsEltonNilsen) January 30, 2014

https://twitter.com/ThatPuckBeaut/status/428781313433149440

The laws of physics and gravity are exaggerated way too much in flappy bird 😒

— Gary Scott (@garyscott_) January 30, 2014

The physics in flappy bird is extremely inaccurate.. Not to mention frustrating as crap 😒😠

— Latté☕ (@La_Tayy) January 30, 2014

I wish physics even slightly applied in flappy bird

— craig zeglen (@czegsmd) January 30, 2014

Flappy bird irks. The physics is all off. And im pissed

— Luchini (@Bella_Bonita_) January 30, 2014

https://twitter.com/maaddawwg/status/427833802140815361

Flappy bird defies physics

— Ꮳhrissy Ꭶchweninger⚓ (@pisssychrissy) January 27, 2014

Flappy bird physics is so unrealistic

— Deacon Tersteeg (@Freaky_Deacy13) January 27, 2014

Like on what planet does anything fall that fast?!!?!? Have you ever heard of physics flappy bird??

— Andrew Campos (@rpeacesignohhh) January 28, 2014

Take everything you know about the laws of physics and throw them out the window: that's flappy bird

— Tim Morris™ (@TIMtation_19) January 28, 2014

The law of Physics do not exist in the world of flappy bird

— Brett Bader (@184bader) January 29, 2014

The physics in flappy bird are just non existent.

— Iceburg Simpkins (@StonedChase) January 29, 2014

The physics of Flappy Bird is so bad which is why it's so difficult to play. It's not intuitive like most game mechanics. #sodumb

— Victor (@veeedoh) January 29, 2014

 

So, is the physics unrealistic in Flappy Bird?

Sounds like a job for Logger Pro video analysis! I used my phone to take a video of Flappy Bird on my iPad. To keep the phone steady, I placed it on top of a ring stand with the iPad underneath.

(I’ve uploaded several of the videos here if you’d like to use them yourself or with students: Flappy Bird Videos.)

Then I imported the videos into Logger Pro and did a typical video analysis by tracking Flappy’s vertical position in the video. Sure enough, the upside-down parabolic curves indicate Flappy is undergoing downward acceleration.

But do the numerical values represent normal Earth-like gravity or insanely hard Jupiter gravity? In order to do this, we need to (1) set a scale in the video so that Logger Pro knows how big each pixel is in real life and (2) determine the slope of Flappy’s velocity-time graph while in free fall, which is equal to the gravitational acceleration.

The only thing we could realistically assume is the size of Flappy Bird. If we assume he’s as long as a robin (24 cm), then the slope of the velocity-time graph is 9.75 m/s/s, which is really close to Earth’s gravitational acceleration of 9.8 m/s/s. Flappy Bird is REAL LIFE.

So then why is everyone complaining that the game is unrealistic when, in fact, it is very realistic? I blame Angry Birds and lots of other video games. Repeating the same video analysis on Angry Birds and assuming the red bird is the size of a robin (24 cm), we get a gravitational acceleration of 2.5 m/s/s, which only 25% of Earth’s gravitational pull.

In order to make Angry Birds more fun to play, the programmers had to make the physics less realistic. People have gotten  used to it, and when a game like Flappy Bird comes along with realistic physics, people exclaim that it must be wrong. As one of my students notes:

@fnoschese looks like those sorry folks need themselves some logger pro

— Sam Wolfson (@sam_wolfson) January 30, 2014

 

UPDATE 31 Jan 2014:
Inspired by a tweet from John Burk,

@fnoschese you know what would make an awesome demo, dropping a ball and watching it fall with same accel as flappy bird. +

— John Burk (@occam98) January 31, 2014

we made a video showing Flappy Bird falling at the same rate as a basketball:

Here’s what I did: We determined from the analysis above that Flappy Bird is about 24 cm across. Conveniently, basketballs are also about 24 cm across. So I had my physics teacher colleague Dan Longhurst drop a basketball so I could video it with my iPad. Dan just needed to be the right distance away from the camera so that the size of the basketball on the iPad screen was the same size as Flappy Bird on the screen (1.5 cm). Next, I played the basketball drop video and Flappy Bird on side-by-side iPads and recorded that with my phone’s camera. Once I got the timing right, I uploaded the video to YouTube, trimmed it, made a slow motion version in YouTube editor, then stitched the real-time and slow motion videos together to create the final video you see above.

UPDATE 1 Feb 2014: While the gravitational acceleration in Flappy Bird is realistic, the impulse provided by the taps are NOT realistic. Here’s a velocity-time graph showing many taps. When a tap happens, the velocity graph rises upward:

As you can see, no matter what the pre-tap velocity (the velocity right before the graph rises up), the post-tap velocity is always the same (a bit more than 2 m/s on this scale). This means that the impulses are not constant. In real life, the taps should produce equal impulses, which means that we would see that the differences between pre- and post-tap velocities are constant.

TL;DR: Is the physics in Flappy Bird realistic? Yes AND no.
YES: The gravitational pull is constant, producing a constant downward acceleration of 9.8 m/s/s (if we scale the bird to the size of a robin).
NO: The impulse provided by each tap is variable in order to produce the same post-tap velocity. In real life, the impulse from each tap would be constant and produce the same change in velocity.

UPDATE 1 Feb 2014 (2): Fellow physics teacher Jared Keester did his own independent analysis and shares his findings in this video:

 

Video Analysis of a Bouncing Ball

Nothing earth-shattering here. I just wanted to share the activity we worked on today, which was an introduction to quantitative energy conservation by doing a video analysis of a bouncing ball. (Up until now, we were only doing qualitative energy pie charts.) Here are the handouts and the video:

• PreLab: Energy of a Bouncing Ball 2013 (docx)
• Lab: Energy of a Bouncing Ball 2013 (docx)
• Ball Bounce Video (avi) — From Ball State’s Video Analysis: Real World Investigations for Physics and Mathematics

The graphs from the analysis are just beautiful:

Lots to talk about in those graphs!

Feel free to edit and reuse the handouts as you see fit. They’re not perfect, but I figure it’s better to share them than having them collect dust on my flash drive.

PS: I’ll sheepishly admit that I don’t do the whole suite of paradigm labs in the Modeling unit to mathematically derive the energy equations from experiments. But we do some simple qualitative demos/experiments to discover what variables would be in those energy equations. We start by talking about how the further a rubber band is stretched, the more energy it stores. Then we launch carts into a rubber band “bumper” (i.e., big rubber bands from Staples and two C-clamps) to qualitatively see the energy stored.

In doing so, we see that the cart’s kinetic energy depends on its speed and its mass. (Or is it weight? What would happen if we repeated the experiment on the moon?)

For gravitational energy, we can repeat the experiment, but have carts rolling down an incline. Or use the rubber band to launch the cart up the incline. I’ve also dropped balls into sand and looked at the depth to which they get buried. Either way, we see that gravitational energy depends on height and weight. (Or is it simply mass? What would happen on the moon?)

For elastic energy, we already know it depends on the distance the rubber band is stretched. Then, we can swap out the rubber band in the bumper with a stiffer/looser one to see the effects of the spring constant on energy stored.

Then, after we predict what the energy equations might look like, I just give them the actual energy equations, or have them look them up. (Gasp! See Schwartz’s A Time for Telling, aka Preparation for Future Learning.)

So, modelers, what am I missing by not doing the full-blown energy paradigm labs? How do you introduce the quantitative energy equations?

Going Beyond the Physics Textbook

I have the honor of being invited by Discovery Education to attend their second “Beyond the Textbook” forum to be held this Wednesday and Thursday at their headquarters in Silver Spring, Maryland. The event is spearheaded by Steve Dembo and, in exchange for travel expenses, he gets to pick my brain about digital textbooks, resources, and curriculum. There will be 18 other outstanding educators as well, including my edu-heroes  Christopher Danielson, Michael Doyle, Karl Fisch, and Tom Woodward.

In preparation for the event, I’m updating/remixing an old blog post I wrote called “My Vision for a Physics iBook” ….

~~~~~~

I keep thinking about what a physics iBook would look like. Not a book for consumption, as with a traditional text, but rather a book to enable exploration. So what would a student see when they first opened such a book?

It’s blank.

No content. No classical references like Feynman’s Lectures on Physics. No integration with Khan Academy’s video library.  Nothing.

Why?

Students should be learning to do science, not simply learning about science. They should be making observations, posing questions, conducting experiments, finding patterns, analyzing data, and sharing their conclusions.

In this sense, the iBook would function more like an electronic lab notebook. As with curricula like Modeling Instruction and ISLE, students would create the physics content from their own investigations and evidence, rather than deferring to authority.

Actually, the iBook wouldn’t be completely blank. While it would initially be empty of content, it would be chock-full of tools to help students collect and analyze experimental data. Software like Tracker for video analysis, VPython and GlowScript for computation and visualization, LoggerPro for graphing and electronic data collection, along with PhET simulations and Direct Measurement Physics Videos for conducting virtual experiments.

In the realm of traditional physics textbooks, only a few make it a priority to incorporate experiments into their storylines. Three that come to mind are:

The Manga Guide to Physics

Understanding Physics

FIGURE P-2  Electronic temperature sensors reveal that if equal amounts of hot and cold water mix the final temperature is the average of the initial temperatures.

and PSSC Physics.

Eugenia Etkina‘s upcoming College Physics text gets a step closer to my iBook vision. The text incorporates her work with video experiments in her ISLE and Physics Union Mathematics curriculula. In the text, there are QR codes which link to videos of the experiments to be analyzed.

For example, here’s a video of a momentum experiment, followed by the corresponding section of the text.

But, as you can see, the text does the analysis for the student. In my opinion, this would make a good reference only after the student has completed a similar activity on their own. Fortunately, her text also comes with a workbook that asks students to do this sort of scientific reasoning on their own:

Also taking the “experiments first” approach is Live Photo Physics Interactive Video Vignettes, a collaborative project by well-known physics education researchers Robert Teese, Priscilla Laws, and David Jackson. During a vignette, students are asked to make predictions and do video analysis on-the-fly. Here’s a preview:

Science is never done in isolation, however, so the iBook would come equipped with tools for sharing data, content, photos, videos, and resources among students and between teacher-student.

For me, going beyond the textbook means giving students a toolbox rather than an instruction manual.

What’s your vision for the future of textbooks?

You can follow along with us at the Beyond the Textbook forum this week by searching for the Twitter hashtag #BeyondTextbooks.

Bonus: 5 reasons why iPads won’t replace textbooks in science class.

Projectile Motion Assessment Task

You are a game designer for Rovio Entertainment, the company that makes Angry Birds.  The human resources department wants your input. They are hiring several programmers to build the physics engine for Rovio’s newest game. Here are the demo videos from the top four applicants. Which applicant(s) would you recommend for hire?

Applicant A

Applicant B

Applicant C

Applicant D

Download the original video files for analysis in Logger Pro or Tracker.

These videos were not created by me. I found them online several years ago, but I can’t remember where. If anyone knows, please tell me so I can give the creator proper credit. Thanks!

My TEDxNYED Session: Learning Science by Doing Science

Many thanks to the TEDxNYED 2012 crew, especially True Life Media, Basil Kolani, Karen Blumberg, and Matthew Moran for an awesome event. Be sure to check out the rest of the TEDxNYED 2012 talks.

Learn more about Modeling Instruction in Science.

My Vision for a Physics iBook

UPDATE 1/22/2012: Now with links and Apple’s iBook video!

Warning: This post is a brain dump of all thoughts and conversations I’ve been having about next generation textbooks since Apple’s iBook textbook announcement. Sorry this isn’t polished.

I keep thinking about what a physics iBook would look like. Not a book for consumption (like a traditional text) but rather a book to enable exploration. More like a text-journal-workbook-lab notebook combo, where students would create content from investigations (also pooling created content/data from classmates, etc) and also have reference text for afterwards in the same vein as the Minds-On-Physics text, the first edition of M&I, and the Physics by Inquiry texts.

Stuck on a problem? An intelligent tutor would be able to re-direct you back to a video or animation or even your own data from an exploration where you initially encountered the concept.

There would be these components:

• PeET sims
• Physlets
• Interactive Learning Demonstrations (ILDs) — real life and virtual
• Etkina’s video labs
• Mastering Physics/Andes/WebAssign type problems and tutors
• Van Heuvelen’s active physics problems and ALPS (Active Learning Problem Sheets — out of print)
• Wolfram alpha widgets / animations / investigations
• VPython
• Diagnoser / Formative Assessment Probes
• Data/content/photo/video sharing among students and between teacher-student
• Video Analysis for built in cameras
• Collaborative Whiteboard software
• Integrates with Facetime
• Clicker-type Peer Instruction questions for in-class and out-of-class use
• Leveled assessments — get question right, next one is harder, etc. — Better to gauge how well student has mastered a standard.
• SBG grading and reporting built in
• PSSC film clips
• Video demonstration library film clips
• Vernier sensor connections for data collection capability
• Mathematica/SAGE/etc.
• When students answer assessment probes or clicker-questions, can automatically sort kids into heterogeneous or homogeneous groups for discussion.
• Ability to connect to projector
• Abiltity to view teachers and classmates screens
• Ability for students to take video/audio of class meetings and file/tag them (along with other materials) by topic/unit/date/etc.
• YouTube video / Win-Fail / anyqs / wcydwt  / wqdyh type stuff
• Tools and content from Open Source Physics (Tracker, Easy Java Sims, etc.)

It’d be like an electronic version of the PSSC/Modeling/ISLE /PUM curricula on steroids. And I see this more as the teacher having these tools to deploy to the students, rather than the students following a linear path through text and activities. The class actually builds the text together, and each year the text is different.

The capabilities and content for this iBook already exist. No one has put them together in one package yet. I think it could even be web/cloud-based and platform independent if done with the proper tools.

What am I missing? What’s your vision?

Physics of Angry Birds Lesson on CUNY-TV

Many thanks to Ernabel Demillo and the crew of Science and U!

You can read more about how we use Angry Birds in class here:
Angry Birds in the Physics Classroom

Meet a Modeler: Colleen Megowan-Romanowicz

Today’s guest post is from Colleen Megowan-Romanowicz, the Executive Officer of the American Modeling Teachers’ Association. It is the fifth post in a series which shares the stories of teachers using Modeling Instruction.

Colleen writes:

I am a physics teacher. I have been teaching for 25 years, and I have taught many other subjects, but my identity as a physics teacher is as firmly grounded in the texture of my being as my identity as mother, “leftie”, and redhead.

I entered teaching through “the back door”, when my first choice career, medicine, was no longer an option. In elementary school, I wanted to be president of the United States, in high school I was hooked on marine biology, but when I entered college in 1969, I was committed to pre-medicine. Four years later, in classic overachiever fashion, I not only had a bachelor’s degree, but a husband and two children as well. By age 23, I had given birth to my third child and come to the realization that medical school was out of the question. I considered nursing, but thought it likely that I would harbor secret resentment toward the doctors with whom I worked. Teaching seemed the only other practical alternative for someone with a biology major and chemistry minor, so back to school I went. A year later, when I completed student teaching I knew I had, quite by accident, found my calling.

Twenty two years ago I began teaching physics—not a trivial task for someone who had completed college physics 18 years earlier. But how hard could it be, to stay ahead of 12 seventeen year old girls in one section of high school physics? (I taught at a girls’ Catholic high school in Sacramento) I unearthed my old physics books, bought some new ones, and discovered what I had missed completely the first time around. Physics is the foundation. It is why chemistry and biology exist. It is both a context and a rationale for mathematics.

It was a life changing realization—my kids joked that it was like God’s voice from the burning bush. From then on, I wanted to become the best physics teacher I could be. I took classes and workshops. I gave classes and workshops. I discovered that to be a good physics teacher I needed to be a good mathematics teacher, a good cognitive scientist, a good linguist and discourse analyst, even a good philosopher. And by all accounts I was good. I had plaques and certificates to prove it. I grew the physics program at my high school and converted it to physics-first. We went from 12 students to over 170 (in a school with just under 500 students—all girls). But I knew deep down I wasn’t really that good. My students learned to solve tricky physics problems and they could get into good colleges, but they never did that well on the FCI.

In 1998 I discovered Modeling Instruction…another life changing experience. After my first Modeling Workshop at UC Davis (led by Don Yost and Wayne Finkbeiner…Mark Schober, our current AMTA president, and I were classmates in that workshop) I went back into my classroom thinking I finally had the key to really helping my students learn physics. Unfortunately things didn’t unfold quite as I had imagined. I was not brilliant. I struggled and so did my students, but even inexpertly implemented, I could see how much better modeling was at revealing what my students were thinking. The following summer I went back to Davis for my second Modeling Workshop and the next school year I did better (and so did my students). By year 3, I finally felt like I knew what I was doing. I became intensely curious about how and why modeling worked for my students. I read whatever I could get my hands on, but finally decided that if I was going to figure modeling out, I’d have to be systematic about studying it. I needed someone to guide my studies, and since I had met David Hestenes while I was at UC Davis and he encouraged me to look into a program in physics education research, I contacted him and asked if I could be his graduate student. He agreed.

Although I loved teaching at Loretto High School for Girls in Sacramento, ten years ago I moved to Phoenix, took the job of designing the mathematics and science program for the new Jewish high school (a physics first integrated science and mathematics curriculum), and began my graduate studies at ASU. My research interest was in the integration of physics and mathematics, the physics first sequence of instruction, and the ways in which student discourse shapes thinking and reasoning in physics. I completed the Physics Department’s Master of Natural Science (MNS) degree program in 2004, along the way engaging in the first of many classroom research projects in collaboration with three other teachers. We designed and tested a modeling instruction unit in special relativity. During this period I also began teaching the Leadership Workshop course and coordinating the action research component of the MNS program. Over the years I have mentored over 40 teacher action researchers through their required MNS research experience. In fact it was during a Leadership Workshop meeting one day I heard that a handful of teachers in the Advanced Modeling course who were concerned about the future of modeling instruction, had invented AMTA the night before over a pitcher of beer (or 2). I immediately took out my checkbook and wrote Patrick Daisley (another UC Davis modeling classmate, who still serves AMTA as treasurer) a check for $25 to become one of the charter members of the organization.

In 2007, under the guidance of David Hestenes, I earned my PhD in Physics Education Research from ASU. My research was a study of whiteboard mediated cognition in four different modeling classrooms. After doing a year of postdoctoral research on embodied cognition in science education for ASU’s Arts, Media and Engineering program I took a faculty position in one of ASU’s colleges of education (we had 3 of them at the time) teaching elementary science methods. I secured funding for the Modeling Institute—a middle school STEM Modeling MNS degree program. Last summer I gave an invited talk and a demonstration of modeling instruction in Beijing. (They loved it. Chinese teachers want to learn modeling instruction.) In the fall I started writing grants in earnest to obtain funds to help scale AMTA up. To date I have written four grants. None have been awarded yet—I think perhaps the NSF reviewers are having a hard time wrapping their brains around a grassroots organization of this type. This spring I offered my services to the AMTA executive board as executive officer. When they took me up on it, I resigned my faculty position at ASU and accepted a part-time research position so that I could devote as much time as possible to helping AMTA “go big”. (I am fortunate to have the support of a loving husband who tells me I should do what makes me happy.) My AMTA position will not be salaried until I can land us some external funding.

Pedagogically, I approach teaching via modeling theory, and cognitively I am particularly interested in the phenomenon of distributed cognition and how a situated group learning experience ultimately distills into individual student understanding. I am also convinced that mathematics and science instruction can and should be integrated. I undertook this with good results for three years at the Jewish high school, and I built this curriculum design into the NSF-funded master’s degree program for middle school teachers. I hope that my work will enable modeling instruction to become self-sustaining and I would like contribute to large-scale curriculum integration in mathematics and science. At the very least, I hope that by having a foot in both the mathematics education and physics education camps, I can foster a dialogue and an ongoing relationship between the two communities that ultimately enriches both.

Meet a Modeler: Fran Poodry

Today’s guest post is from Fran Poodry, the president-elect of the American Modeling Teachers’ Association. Fran teaches high school physics in Pennsylvania. It is the fourth post in a series which shares the stories of teachers using Modeling Instruction. Fran writes:

I was a physics major in college and I knew all along that I wanted to become a teacher.  I took all my undergraduate education courses at a small private liberal-arts college, where I learned many things that are now called “21st century education” which I find humorous. Since I planned to teach, a professor I knew (but not at my school) suggested I join the physics teaching mailing list, PHYS-L, and from there I learned about Physics Education Research.  I also got to know (virtually) Joe Redish, Dewey Dykstra, Priscilla Laws, and others.  I wound up working for Priscilla Laws for two summers, learning about Workshop Physics, Vernier probes and interfaces (remember the ULI?) and analyzing data from student surveys pre- and post-instruction.

I graduated with a BA in Physics and a Pennsylvania teaching certificate in 1992, and I have been teaching physics since January, 1993.  I taught for five and a half years in Philadelphia public schools. Jane Jackson recruited me for a modeling workshop when I attended a summer AAPT meeting at University of Maryland (having known me from my online presence), and  I took modeling workshops in 1997 and 1998. These workshops were at University of Wisconsin-River Falls and were led by Rex Rice and Dave Braunschweig. I still make Rex’s guacamole recipe—yum!

As with many, my life was changed by Modeling Instruction.  I felt like I had discovered the way I wanted to teach, I just hadn’t figured it out before.  Also, I was amazed by how much physics I learned at the workshops! Though I loved using Modeling Instruction, the situation in my school was taking its toll.  The large class sizes, under-prepared students, tragic events, and the bars on the windows were all hard to deal with.  I decided I had to leave Philadelphia or leave teaching.  I left the School District of Philadelphia in 1998.

After leaving Philadelphia schools, I have been teaching in various suburban districts in New Jersey and Pennsylvania.  I love my current school (where I am starting my 10th year), and I have great colleagues, but only one of my colleagues is also a Modeler (though we have four full-time physics teachers in my building).  I have used Modeling Instruction with kids in conceptual classes, honors classes, and in-between, and from a variety of socio-economic levels.  I have struggled to use Modeling with my AP students, since they have already (mostly) had a year of Modeling Instruction in their first-year physics class with my colleague. While I have enjoyed teaching mostly conceptual-level classes and AP classes for the past 8 years, I am looking forward to teaching honors-level and AP classes this school year, and trying out Standards-Based Grading.

I joined the AMTA board last year as Vice President, so am currently the President-Elect and I will be President next year.  I feel very strongly that the work of AMTA is vital for keeping Modeling Instruction alive and growing and funded, unlike previous worthy programs that were not self-sustaining (IPS, PSSC, Project Physics, etc). One way that to help this happen is through greater publicity.  Most science teachers in my district have no idea what Modeling is, and when offered a 2-hour introduction on an inservice day, only two teachers (out of over 40 high school science teachers) came to the session – the rest chose other sessions.  Not only teachers need to know about Modeling Instruction, the word also needs to get out to the politicians, the parents, and the voting public.

You can follow Fran Poodry on Twitter: @MsPoodry.

A Demonstration of the Ineffectiveness of Traditional Instruction

First, answer this question:

A student in a lab holds a brick of weight W in her outstretched horizontal palm and lifts the brick vertically upward at a constant speed. The force of the student’s hand on the brick is:
     A. constant in time and equal to zero.
     B. constant in time, greater than zero, but less than W.
     C. constant in time and equal to W.
     D. constant in time and greater than W.
     E. decreasing in time but always greater than W.

Now watch this video. Feel free to pause, rewind, and rewatch as needed.

Finally, answer this question again:

A student in a lab holds a brick of weight W in her outstretched horizontal palm and lifts the brick vertically upward at a constant speed. The force of the student’s hand on the brick is:
     A. constant in time and equal to zero.
     B. constant in time, greater than zero, but less than W.
     C. constant in time and equal to W.
     D. constant in time and greater than W.
     E. decreasing in time but always greater than W.

Believe it or not, the concept needed to reach the correct answer is given in Khan’s video. Highlight below to reveal:
C. constant in time and W. Why? Since the brick moves at a constant velocity, the forces on the brick (you and gravity) must be balanced.