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  1. baseball00
    Latest Entry

    Our last unit in AP physics c was rotational motion. In this unit we learned about rotational kinematics, dynamics and momentum. Rotational kinematic is very similar to translational kinematics because the same kinematic equations are used. The difference is that instead of displacement roation has the change in the angle. Instead of translational velocity and acceleration, rotational motion is calculated with angular velocity and acceleration.

    As far as dynamics go, rotational motion has a very significant concept that separates it from translational motion. It's moment of inertia. Moment of inertia is the measure of an objects abilty to resist rotational motion. It could be compared to inertial mass or just mass. The other importance to rotational dynamics is the concept of torque which is a force that causes rotation mesured in Newton*meters. Torque is equal to the moment of inertia of the rotating object times its angular acceleration. Torque is also equal to the cross product of force and the distance from the axis of rotation that force is applied. Rotational dynamics is important for solving many different problems involving rotation.

    Rotational or angular momentum is the measure of how difficult it is to stop a rotating object. It can be calculated using the equation L = moment of inertia * angular velocity. Angular momentum is also equal to the cross product of the objects radius and its translational momentum. It is important to know that angular momentum is always conserved, so in a closed system the intitial angular momentum is equal to the final angular momentum. 

    Rotation is a very important topic because it is so useful in the world of science and engineering because not everything moves in linear motion. For instance our solar system can be studied using rotation since our planets move in rotational paths.

  2. HegelBot153
    Latest Entry

     I purchased a bike with the money I made last summer at my dreadful waitstaff job. Anyways despite the working conditions, I now had a used bicycle with several neat gears and a chain. Now I believe that these gears have some relation to my cycles per unit-of-time which I believe is similar to a 'frequency'  or cadence of turns on the main gear, perhaps similar to rotational velocity. A second gear operates the driver wheel which lends it similar amounts of speed if I could be so inclined to say so. I am terribly hesitant to draw conclusions, I know. Please forgive my tone but I digress. Anyways the real exciting part was the possible gear ratios, probably around twelve combinations, that all have a part to play in the torque and speed of the driver wheel which is coaxial with the driven gear. The translational speed of one gear is the same as the other however the rub is that the force and rotational speed of this combination depends on the gear ratio and radius. Essentially the driven gear receives from the input gear, the one I peddle, its speed and then a certain gear reduction arises from the quantity; gear ratio. A smaller gear operating on a large gear produces higher torque and lower angular speed while a larger gear operating on a smaller gear has lower torque and higher speed. 

  3. MyloXyloto
    Latest Entry

    On Monday we were given a problem: Make a spinning top.  We had two paper plates, six pennies, a sharpened pencil, and some tape.  With no further instructions given, we were left to our own devices to solve the problem.  Though I cannot speak for my partner, I can say that I was not thinking of the engineering design process at the time.  However, the engineering design process was precisely how we were going about our task.  We had a problem to solve and we began by constructing our solution.  We taped the six evenly spaced pennies to the outside of one plate, then put the other plate on top.  We poked the pencil through (roughly) the center of the plates.  Then, we tried testing our results.  When it didn't work perfectly the first time, we made adjustments.  We would try placing our mass at different heights on the pencil.  We found that it worked the best when it was lower.  However, we did not pick up that we should have snapped the pencil in half to make the top more stable.  We learned this after.  Moment of inertia was crucial in this lab because a higher moment of inertia would mean the top would have greater angular momentum.  Increased angular momentum would mean that the top would be more resistant to change in its rotational motion and stay spinning longer.  We tried to maximize the moment of inertia of the top by placing the mass (the pennies) by the edge of the plate.  This way, the radius was greater.

  4. On Monday during physics class, we were asked to create a “top” that would spin for a long period of time. The materials we were given included two small paper plates, a pencil, six pennies, and tape. At the end of the lab experiment, we were asked to answer the following questions in a blog post:

    How did today's opening activity relate to the engineering design process?

    The engineering design process involves designing, building, and testing something. This relates to what we did in class because we had to brainstorm solutions to the given problem, and then we built, tested, and redesigned various models. For example, we tried moving the pennies closer to the center of the plate, and then we tried moving them farther to the outsides. We also experimented with moving the plates farther up and down the pencil. Unfortunately I carelessly poked a hole through the plates that was off-center and this impacted our results. Oops!In the end, we learned that the task would've been much easier if we had snapped the pencil in half.

    How did today's opening activity relate to moment of inertia and angular momentum?

    If friction did not exist, the top could keep spinning forever. But because there is friction, you want to maximize the angular momentum of the top so that it takes longer for friction to stop the top. You can increase angular momentum by increasing pieces of rotational inertia such as mass and how far away the mass is from the center (or the radius). We did this by putting all six pennies evenly spaced on the outside edges of the plate.

  5. The Engineering Design Process:

    Image result for engineering design process

    The Engineering Design Process is designed itself to help outline how engineers (or anyone really) can solve a problem. We used this process when making the spinning tops in class, even if we did not know it at the time. Now let's go through it using the example of creating a spinning top, like we did in class. 

    We Defined the Problem when we were given instructions: make a top.

    We had already done Background Research when we were working on understanding moments of inertia, it is determined by different equations for different objects, mostly relating to the radius of the object, or the length from where the object is revolving around.

    Our Specified Requirements were that it stood up long enough to be considered a top and that it was made only from the limited materials we were given.

    As a team, we Brainstormed and chose a solution that we put the pennies on the plate, and put the pencil in the middle, so that it would allow the pencil to stay upright. We then used that solution to develop a prototype, and we went through testing our solutions and based on our results, we made changes to our design. We found that moving the pennies closer to the base of the pencil allowed it to stay upright a lot longer.

    This process was repeated until we finally found a suitable final product, however, any design could always be better.


    The Engineering Design Process does not ensure a positive result every time, perhaps your results find that there is not a possible solution with the limited resources or knowledge that you  have, in that case you would still communicate your results so others can see what you did and possibly come up with a better result. For example, we made a top that worked well, but another group found something that we didn't, if you cut the pencil down to make it shorter, it would stay up even longer, this is because the pencil tends to fall less when the radius is shorter (the pencil moved more about the top than the bottom, so making it shorter solved this problem).

  6. jrv12
    Latest Entry

    In physics class earlier this week, we were presented with a task to make a top out of two mini paper plates, a pencil, six pennies, and tape. Without any instruction, we had to create a top and make it spin for a decent amount of time using these materials.

    The engineering design process played a big part in our creation of a top, even though we didn't know it at the time. The steps of the engineering design process are: define the problem, do background research, specify requirements, brainstorm and choose a solution, develop and prototype a solution, test solution, solution meets requirements, and communicate results. The problem was to create a top and the background we had was we saw one working before we started to design our own. The brainstorming area had to be cut short based on time, so we went right into making our solution. Once our first solution didn't work out as we were testing it, we mostly resorted to trial and error. While we were never successful in getting the top to spin for more than a couple seconds, some of our classmates were.

    A top relates to moment of inertia and angular momentum because the moment of inertia depends on mass and radius, so including all of the pennies spaced out to the edges of the paper plates created the most inertia. Angular momentum depends on the moment of inertia and angular velocity, so the greater the inertia and angular velocity, the greater the angular momentum, and therefore the time the top will spin. I now understand the difficulty of the engineering design process and how many tries it takes to finally come up with a perfect solution based on the proper equations.

  7. The objective of the lab TheNightKing and I performed this week was to create a functioning top with the given materials of a pencil, 2 paper plates, 6 pennies, and tape. In relation to the engineering design process this would be the problem or objective we need to focus our ideas around.

    Our next step would be research, but , due to our lack of time, we pulled from our knowledge gained throughout this past unit and our previous year physics. One of the main principles to keep a top up is angular momentum. The equation for spinning angular momentum is rotational inertia x angular velocity. So we need to spin it as fast as possible and, most importantly, we need to give it the largest quantity of rotational inertia possible. So, ignoring the pencil rod at the moment and plates, we knew we needed to get the pennies as far away from the center as possible since the equation of a mass away from the axis of rotation for a given mass is mr^2.  So, by increasing the radius, we could get a larger quantity of spinning angular momentum.

    Stating and listing the requirements would be the next step in the engineering process, but we were already given them in the objective.

    The next step is to brainstorm, evaluate, and choose solution. We chose to use the pencil as our main post and then centered and poked it through the two plates. We then taped the pennies to the outskirts of the plate as this would put their mass at the farthest points away from the center of mass as possible.

    Our prototype was created and now we began testing. The top originally wobbled so much that it wouldn’t spin so we adjusted the pennies. We Adjusted until we had the top balanced which decreased the wobble dramatically.  That being said, it was not as stable as we ideally would like. This is when FizziksGuy gave us a nudge in the right direction by asking which part was the most unstable. We both noticed that it was the very top of the pencil. In our efforts to make the top more stable, we broke the pencil to a fourth of the size and therefore dramatically lowering the center of mass. Now the top was much more stable as the distance of the center of mass from the ground is substantially less than before.  

    After all this testing, we felt our top was substantially more stable and adequately addressed the problem, being able to spin for longer than 30 seconds at a time. The last step in the engineering design process is communicating our results which coincidentally are all explained above. Engineers are used not only to create solutions, but to improve on the efficiency of current ones, so to this effect, had we had a longer time frame I am sure the results could have been even better.

    As always thanks for reading! - ThePeculiarParticle

  8. This past week, we did a small partner lab. Our mission was to make a top out of the following materials: 2 paper plates, a plain wood pencil, 6 pennies, and tape. The top also had to be able to spin for more than only a few seconds. However, there were no instructions other than to make a top. Immediately, each student in the room with his or her partner immediately began undergoing the engineering process, whether they knew it or not.

    The engineering process has steps to be done in this order -- Define the problem, do background research, specify requirements, brainstorm solutions, choose the best solution, do development work, build a prototype, test and redesign. We already knew the problem, and we were presented with a top to look at in the back of the room, so we already defined the problem and did a little research on tops. The requirements were to make the top with the materials provided, and the top must spin for more than only a few seconds. We brainstormed quickly and then talked about our ideas on how to make the top. We then chose to mix our ideas together to get the best solution possible and we discussed who was to make it and walked through it together. Soon, we had a prototype and we were able to test that design. If it did not work that well, we tried something new. This lab, in a nutshell, was a little simulation of the engineering process!

    This lab also shows a relationship between tops, angular momentum and moment of inertia. As the top spins, the angular momentum generated points straight up into the air, and if there were no friction, the top would spin forever because the momentum that holds the top up is forever conserved unless acted on by an outside force. The moment of inertia of the top is the rotational analog of the mass of the top. The angular momentum discussed above is the result of the top's moment of inertia times the rotational velocity.

  9. crazycrochet20
    Latest Entry

    Wow! It is already December and we are working on rotation in class! Last year, this unit was one of the worst for me because I truly did not understand any of the concepts. I have started to figure out some of the equations and concepts but, I am going to have to work hard all this week in order to really understand the unit.

    In class last week, Mr. Fullerton gave us a challenge to solve. He gave us a pencil, two small paper plates and six pennies. Our task was to make a top that would spin for a longer period of time from those materials. For the blog post this week, we have to explain how this activity relates to the engineering design process. If I am being honest, I had no idea what it was and typed it right into the handy dandy Google. I found a website (sciencebuddies.org) which gave me the steps to the engineering process. 

    Those steps are:

    • Define the Problem
    • Do Background Research
    • Specify Requirements
    • Brainstorm Solutions
    • Choose the Best Solution
    • Do Development Work
    • Build a Prototype
    • Test and Redesign

    I definitely think that all of these were used in the activity with some of them slightly combined and happening all at once. Our problem was creating the top that would stay spinning for more than just a few seconds. Our research came from the information that we could see coming from the actual top and our background knowledge from the physics we had been learning. The requirements came in the form of the items we could use to make the spinning top which were the pencil, paper plates and pennies. The next few steps were combined because of time and we began to use trial and error to try and build the top. Brandon and I immediately knew that the the plates would have to have the pencil going through the center. We tested out where the plates would have to go on the pencil and eventually found that it had to be placed towards the bottom of the pencil. On the plates we tested the different distances of where to put the pennies and ended up putting the pennies at about an even distance towards the outside of the plates. Our final aspect that we fixed to make the top spin longer was put a small piece of tape at the tip of the pencil to keep it from spinning around all over the table. After that, we had created a top that spun for a decent amount of time with the many aspects we changed and tested.

    The next question we have to answer is relating this activity to moment of inertia and angular momentum. For the moment of inertia, the mass and radius are the factors that change moment of inertia. Since we could not really change the mass of the object, spreading out the pennies to create a larger radius impacted the moment of inertia for our top. For the angular momentum of the top, the moment of inertia and angular velocity impacted the top and allowed it to spin for a longer period of time. These two concepts combined created the top with lots of trial and error for the perfect one.

    Until next time,


  10. Did you know that if you run really fast, you gain weight? Don't freak out, it's not permanent nor a noticeable amount. But say you ran as fast as the speed of light, the speed limit of the universe, and someone gave you a push. You wouldn't be able to go any faster, but you gain extra energy, and it's got to go somewhere. Where else but mass? Due to relativity, mass and energy are equivalent. This is highlighted by the universal equation of E=mc2. The more energy you put in, the greater the mass becomes. Unfortunately, this is basically negligible at human speeds, so Usain Bolt isn't noticeable heavier when running than when still. However, once you reach a decent chunk as a fraction of the speed of light, your mass will start to increase rapidly. Thanks, Einstein!

    Gotta go feast

    I'm not sure if you will get this meme but it's sonic the hedgehog, notorious for being fast, clearly enthralled by this knowledge. I found it pretty amusing.

    And thank you, for tuning in. 

  11. Bogart
    Latest Entry

    Guns have vastly improved since their invention, but typically still use a chemical reaction to produce a rapidly expanding gas that shoot a projectile wherever it's pointed. What's the issue with this? Currently, nothing. They're still some of the best weapons in our arsenal. But in the near future, there could be better alternatives: railguns.

    A railgun is, as it's called, a gun. The main difference with it is that the force it uses to fire projectiles comes entirely from electricity rather than a chemical such as gunpowder. How does it work, you ask? Simple: Electromagnets.

    A railgun consists of 2 parallel rails that connect to opposite ends of a power supply, so one is positive and the other is negative. When a projectile is inserted, it completes the circuit, which generates a magnetic field. When using a large enough power supply, this magnetic field can easily launch projectiles to incredibly high velocities. A turret mounted on the top of some tanks can fire a projectile at over 1.5 km/s, while a railgun could fire a projectile at over 2.5 km/s, giving it a much farther range and a much quicker travel time.

    What other advantages do railguns have? Since ammunition in a railgun doesn't require any chemicals to propel it, the manufacturing could be much easier, and ammunition for a railgun could be much smaller than a normal bullet. They'd also be safer to transport because of the lack of explosives and easier to transport due to their reduced weight and size. 

    Am I trying to convince you that railguns are superior in every way? No. I haven't done too much research, I just think that they're really freaking cool. Especially since the US Navy currently has an experimental railgun prototype.

    There's just something about explosions that make me happy.

    Now if you watched the video, you'd notice that the ammunition in the railgun were definitely NOT small. That's because this is a US Navy prototype. This is designed to be shot at big, tough objects, such as a building or a battleship. And from the looks of it, the railgun would win.

    A handheld prototype would definitely be much less powerful, and would probably require many technological advancements before they're practical enough to replace modern firearms. Still, they're pretty cool.

  12. Yankees catcher,  Gary Sanchez, takes some abuse at his position. Not only from public criticism of his struggles blocking pass balls, but also the constant force of catching baseballs for 9 innings of play. In this blog I will examine the force that Sanchez has felt while catching Chapman.

    First, Aroldis Chapman can throw 105 mph (47 m/s) fastballs at Sanchez.


    p= (.145 kg)(47m/s)

    p= 6.8 kg*m/s

    Say the time it takes for Sanchez to stop the ball is .1s

    F= p/t

    F = (6.8kg*m/s)/(.1s)

    F= 6.8 N 


  13. A partial derivative uses this nice formula. (f)/(x), where f:R^2->R is lim h->0 (f(x+h,y)-f(x,y))/h. Physics is everywhere, waiting, watching. 

  14. Hey y'all,

    Chris, a student at Cornell, wakes up at 8:59am for his 9:05 class. If the class is 1.5 km away, at what constant velocity does he need to travel in order to make it to class at 9:05? Neglect air resistance.

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    Recently in an MLB game a fan was struck by a foul ball. This person was severely injured from the baseball. My initial question was why didn't this person just move out of the way. Well, easier said than done. An official league baseball has a mass of .145 kg, and the average velocity of a major league fastball is 40.3 m/s. this means that when the ball hits the bat, if the batter perfectly squares up the baseball, the ball can leave the bat at approximately 49 m/s which is equivalent to 110 mph. The individual that was hit by the ball was on the third base side, first row. This means that there was a distance of 50 meters between the batter and the person hit. The time it took for the ball to reach the fan was 0.92 seconds. Would you be able to react that fast?


  15. madyrice419
    Latest Entry

    I was scrolling through Instagram and found this hilarious meme of someone's Tinder profile. It reminded me of earlier this week when Mr. Fullerton said that if a girl had the quadratic formula tattooed on her forehead, she wouldn't get a date. I guess nerds don't need love. Anyways, I entitled this blog "Dying" because, first of all, that meme made me die of laughter and, second of all, the first AP Physics C test killed me. With reflection I realized that this year is going to be a lot harder than I even first anticipated. I am not the smartest student on Earth, but I have an ambition and unwavering optimism in everything I do. Seeing that I "failed" a test really killed my spirits, and I am hoping that this class will not be the death of me. But deep down I know I can do it. AND YOU CAN TOO. We've just got to keep up with the work and keep trying. I learned that if I get slapped in the face by physics problems, I need to slap them back twice as hard. 


  16. So, in economics, we read this thing about someone who took all  the mints from a restaurant cashier. He was subtle at first, but eventually he just shoved them all in his pocket and left. So that was pretty funny, I'd like to dare one of my friends to try it some time.

    So I just finished that, and then I remembered I had to do a blog post (whoa, bye fourth wall), and it got me thinking about something I learned not to long ago. It's about napkin rings - more technically, spherical rings. I thought about them because, well, mints are toruses, as are napkin rings. That's about it.

    A napkin ring is an object that's the result of taking a solid sphere, and cutting out a cylinder from the center of it, all the way through the sphere. They look like, well, napkin rings. Now, there's a pretty interesting property of napkin rings, that is kinda physics-y, but it's more just mathematical. Although I'm sure there's some interesting physics going along with these, maybe some cool rotational inertia properties. Anyway, the property I'm talking about has to do with the volume of the ring. You see, if you have two napkin rings that are the same height - that being measure one the same axis along which the cylindrical hole was cut - they will always have the exact same volume. Isn't that kinda cool? You could take an orange (well, a spherically perfect orange, in the shape of a perfect sphere), and the Earth (again, a spherically perfect Earth - ours is actually fairly eccentric) and you cut them into napkin rings of the same exact height, they will have the same exact volume.

    Here's a video Vsauce made on the topic (I'll admit, it's not a very exciting video, it's just him going through some basic algebra, and proving this equal-volume property):

    So yeah, there. Something kinda (probably not really for most people, but whatever, I think it's cool) cool about a physical object. See what I did there? It's totally physics related.

    Hey! The first legitimate post, on what's sure to become a pretty cringey blog. See you next week!

  17. Dr. Chew was very helpful in giving me strategies for studying. I have turned in my questions to the videos on a separate sheet of paper in class. 

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    Latest Entry

    I am a student at IHS. As I dive into my senior year I hope to discover new opportunities and interests. I play baseball in the spring and summer. During my free time I like to watch sports or read; however, one of my greatest interests has always been science. I am taking AP physics C this year to further my understanding of the universe. I always knew I liked science, but taking AP physics 1 last year helped me find out that I have a specific passion for physics. In the future I would like to continue my interest in physics by taking it in college and having a career in the engineering field. This year in physics I would like to become more skillful in becoming self taught. This will give me opportunities to become a more innovative person. This year I am most excited about the independence that comes with being a senior. I am anxious for my college research process to come to an end so I can finally apply to the schools and decide where I want to go.

  18. So, it’s been a few years since I’ve detailed how I make my screencasts, and my workflow and equipment have evolved as I’ve added a few bells and whistles in an attempt to make the screencasts look a touch more professional (and more fun).  Some things have stayed the same, and others, well, not so much.  Here’s the basic workflow.

    The Computer

    27" iMac27″ iMac

    I’m still working on a Mac platform, doing most of my work on a 27-inch 2013-vintage iMac.  I try to keep up to date with the latest version of the operating system, which is currently OS X Sierra.  The iMac includes the higher-end graphics card (NVIDIA GeForce GTX 780M 4096 MB), has an i7 processor, and I’ve installed 32 GB of RAM.  Typically when I purchase a computer I shoot for a five to six year productive life span, at which point I’ll upgrade to a newer model.  This has worked pretty well for me with respect to my Mac laptops (a MacBook Pro), as the last one was in service for about six years, but I’m anticipating this iMac may continue well past that mark.  It still looks beautiful, runs quickly, and with the amount of RAM and the built-in Fusion Drive, its performance doesn’t appear to be in any danger of slowing down in the near future.

    Pen Displays

    Wacom Cintiq 22HDWacom Cintiq 22HD

    Attached to the iMac I have a Wacom Cintiq 22HD pen display unit, which is basically an external monitor that I can “write on” with a special pen, allowing me to annotate the screen as I talk through the video.  I’ve previously used a Wacom DTU-1631, and am looking forward to trying out the newly-released Wacom Cintiq Pro 16 with a USB-C enabled MacBook Pro.  Though the Wacom pen displays are a very significant investment, I’ve been very impressed with their quality and longevity.  The DTU-1631 has lasted five years in the classroom with heavy daily use, and the Cintiq 22HD is just shy of five years of service (though a much lighter workload) and could easily pass for brand new.  These monitors also hold their value extremely well over time.

    Audio & Video

    Blue Yeti MicrophoneBlue Yeti Microphone

    I’ve gotten a ton of mileage out of my Blue Yeti USB microphone… I’ve tried a number of other mics, including lapel mics, and microphones that cost more than three or four Blue Yeti’s, but I haven’t found anything that compares to the quality of the Blue Yeti, especially at its very reasonable price point.  If you want to upgrade your audio from the built-in microphones, this is a very solid choice, and another piece of electronics that has held up well for more than five years of service.

    Canon Vixia HF G20Canon Vixia HF G20

    I’ve put together a small office in my basement to allow for a fairly quick and seamless transition to video creation mode, which includes a foam green screen (and stand).  Especially if you’re just getting started, something as simple as a green flannel blanket can work, though I have to admit, the foam green screen has held up extremely well these past few years (even with the dog sleeping on the portion that sits on the floor at least daily).  They sell rather expensive lighting clips to hold the green screen to the stand, but I found quality clips at a much more reasonable price at the local hardware store.

    Genaray SpectroLEDGenaray SpectroLED

    For illumination, I use a couple of super-cheap reflector work lights coupled with a Utilitech Pro floor LED and a Genaray SpectroLED SP-E-240D mounted on the ceiling.  With a little bit of playing, I can obtain pretty reasonable uniform green screen illumination.  I also use a couple of desktop clip-on lamps to illuminate the foreground (i.e. — my face) in the videos.

    To record my face in the videos, I’m using a Canon Vixia HF G20, saving the digital video file onto an SD card.  Most any digital camcorder or webcam can do the job, however.  While the Canon is recording my face, I’m separately using the iMac and Telestream’s Screenflow 6 (Telestream JUST released Screenflow 7, but I haven’t tried it out yet) to record the Wacom Cintiq screen, as well as recording the input from the Blue Yeti microphone.


    Prior to any recording, however, I create my “slides” for the screencasts using Apple’s Keynote software, and export those slides as a PDF.  I then open the PDF using Zengobi’s Curio software, which is the software actively running on the Wacom screen that I use to annotate the slides.  If you haven’t tried it out, Curio is a pretty amazing piece of software that allows you to do so much more than just write on PDF slides…  if you have a Mac, it’s worth checking out for a variety of purposes!

    So, the workflow.  With everything set up, I have Screenflow 6 start recording the Wacom screen while recording the Blue Yeti mic, and simultaneously I start up the Canon video camera.  Once I’ve gone through the lesson, I stop Screenflow from recording and stop the Canon video camera.  I should now have an SD card that contains the digital video file of my face (with sound recorded from the Canon’s rather poor microphone), and a Screenflow 6 file that has video from the Wacom screen coupled with the Blue Yeti-recorded sound.

    Now it’s time to put the video all together.  First I export the digital video file from Screenflow 6, taking care to export at 29.97 fps and not 30 fps so that it will match up to the Canon digital video file.  Then, using Final Cut Pro on the Mac (coupled with the Motion and Compressor add-ons), I create a project and import both the recorded screen video file and the video camera file.  Using Final Cut, I create a combined clip from these two files and have Final Cut Pro sync them up based on the audio (although the sound from the Canon camera is poor, it’s good enough to sync the clips together).  Next, I mute the sound from the Canon camera, so that I now have my recorded screen video below my “live action” video, but using only the sound from the recorded video screen, which was recorded with the Blue Yeti mic.


    Chroma Key EffectChroma Key Effect

    Next it’s time to edit.  First step is to take care of the green screen effect (formally known as chroma key), which Final Cut Pro does quite easily.  I remove the green color from the “live action” file using the “Keyer” effect, and tweak it as needed to get the desired result.  I then shrink the clip down and position it where I want, so that I have the live video taking up just a small portion of the screen, the background green from the video shows as transparent, and what shows through from underneath is the recorded video from the Wacom screen.

    The hard part’s done.  Final steps now involve fixing any audio issues, clip editing if necessary, adding any titles, and appending on the opening and closing video sequences, which were created using Adobe Premiere Pro, After Effects, and Audition from Adobe Creative Cloud.  Once I have the video looking the way I want in Final Cut Pro, I use Compressor to export it in multiple formats — high definition video for YouTube, and an APlusPhysics-specific size and quality for viewing directly from the APlusPhysics site.

    Next Steps

    Moving forward, I would really like to spend some time working with my old iPad to see if I can re-purpose it for use as a teleprompter.  I tend to spend a lot of time up front planning my videos, but still have yet to come up with a slick, efficient way of presenting notes to myself while I’m making a video.  I have to believe there’s a reasonable way to have my notes show up on my iPad and use some sort of remote (perhaps my phone?) to scroll through PDF notes on my iPad as necessary.  Currently I tend to tape my paper notes to the bottom of the camera, which is chock-full of problems, messiness, and opportunity for improvement.

    Back to Reality

    If it sounds like there’s quite a bit of work involved, you’re not wrong, but don’t think you have to go to anywhere near this level of complexity or expense to make quality screencasts.  My workflow has evolved over the years as I’ve tinkered and gone through a length set of try/fail sequences to learn what works for me and provides the level of quality I’m after.  Much of what I do can be accomplished in a similar manner using fairly basic tools — Techsmith’s Camtasia software coupled with a Webcam, a USB lapel mic, and most any digitizing tablet will get you pretty solid results without a huge investment.

    Even though this article is a technical how-to / what do I use, I’d still like to end with two bits of advice I’ve learned from doing things the hard way more times than I can count.

    • First, and foremost, a flipped classroom is NOT about the videos, it is about building more in-class time for active learning strategies such as hands-on activities, group problem solving, deep-dives into a topic, discussions, etc.  The videos themselves are such a tiny part of the whole equation, and are primarily a means to create more available class time.
    • Second, though it can be fun to doctor-up your videos and add all sorts of bells and whistles, realize that these embellishments and investments of time and resources have extremely minimal payback in the form of student learning and performance.  If you’re interested in doing these things, make sure you’re doing them because you want to and think it’s going to be fun, but don’t expect to see any sort of substantial learning improvement with higher quality videos (which brings me back to item one… it’s not about the videos!)

    Useful References

    The post Creating Screencasts (Mac) – 2017 Update #edtech #flipclass appeared first on Physics In Flux.


  19. Hey Mr. Fullerton and anyone whos reading this, its been a pleasure grinding this year. Hope you enjoy this great video and maybe even chuckle a bit. 


  20. Launch Time: 10:37 am

    Team Members Present: Jason Stack, Marcus Nicholas and Michael Kennedy were all present for this launch.

    Play-by-Play: Initially the rocket was created using the parts listed in the pre-flight briefing. The rocket was launched from Kerbin and angled in order to successfully travel outside of Kerbin's atmosphere. The rocket was then directed into orbit around Kerbin. Kerbin was orbited a few times. The rocket was then returned back to Kerbin by using a maneuver that brought the rocket back into Kerbin's atmosphere. The bottom engines were released, then the second engines, leaving only the pod left. The pod descended to 1,000 meters above Kerbin and then the parachute was deployed. The pod landed safely on Kerbin. 

    Photographs: dsd.pngdsds.pngscreenshot0.pngscreenshot11.pngscreenshot12.pngscreenshot2.pngscreenshot3.pngscreenshot4.pngscreenshot5.pngscreenshot6.pngscreenshot8.pngscreenshot9.png

    Time-of-Flight: 4 hours and 5 minutes

    Summary: Our flight was a great success. We planned to accomplish all initial milestones, including a successful manned orbit and a successful Kerbal EVA. All of these desired milestones were accomplished. Our spaceship and Kerbal manning the ship returned safely to Kerbin after successfully reaching orbit around Kerbin. By reaching a manned orbit around Kerbin, all the initial milestones were accomplished by this launch. 

    Opportunities / Learnings: Establishing what the launch goals are and designing the rocket accordingly is very important. Failure to do so will result in an inability to accomplish any milestones.

    Strategies / Project Timeline: After this accomplishment, our next goal is to reach orbit around the moon and land on the moon. 

    Milestone Awards Presented: 

    • Launch to 10 km - $10,000
    • Manned launch to 10 km - $20,000
    • Manned launch to 50 km - $30,000
    • Achieving stable orbit - $40,000
    • Achieving stable manned orbit - $50,000
    • First Kerbal EVA - $60,000

    Available Funds: $257,818

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    Recent Entries

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    This week I focused on chapter 5 in Mechanics.   This included momentum and impulse, conservation of linear momentum and center of mass.

    Areas that went well for me were momentum and impulse and conservation of linear momentum.  What helped me to really understand these two topics were first understand the graphs that went along with them.  This included Force vs. Time graphs showing the impulse to be the area under it.  These graphs gave me a better understanding of what I was solving for when I got to problems.

    Center of mass was the topic I had the most difficulty with.  However plotting the points on a graph helped me with this as well.  The equation Xcm= (m1x1+m2x2).../m1+m2... really helped me understand finding the center of mass of different points.  Finding it for other objects such as rods however was still quite challenging.

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  21. NisaVyv
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    Not many people put a whole lot of thought into what their morning cereal is made of. Most people would just assume there's some grain and maybe a little sugar, or a lot of sugar if you're more of a Lucky Charms person than a Raisin Bran person. Nobody would suspect, though, that there would be metal in their Cheerios. Turns out, Cheerios are magnetic. Or are they?

    Fill a bowl with water and drop in a couple Cheerios. Take a magnet and hold it just above the Cheerios, the Cheerio will be attracted toward the direction of the magnet. Why is this? If the little cereal ring is magnetic, then there must be metal fragments in it causing the attraction. Now the cereal is all magnetic, and it does contain tiny fragment of iron. This is perfectly reasonable though, as iron is a key nutrient in a human diet. But that's not the whole story, 

    If you were to try this with objects other than cereal, say a small piece of paper or plastic, it would still seem to be attracted to the magnet as it floated in the water. The "attraction" you see is actually all about water, which is diamagnetic, meaning it generates a magnetic field opposite to that of the magnetic field it is in the presence of. Thus, the water is slightly repelled by the magnet. This causes a slight divot in the water, that the object in the bowl actually falls into, making it appear to follow the magnet. In actuality, it isn't being affected directly by the magnetic field, but by the waters reaction to the magnetic field.

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