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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.

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Video Discussion: Altitude of Geostationary Orbit (a special case of Geosynchronous Orbit)
Flipping Physics posted a topic in Video Discussions
Name: Altitude of Geostationary Orbit (a special case of Geosynchronous Orbit) Category: Circular Motion & Gravity Date Added: 20171211 Submitter: Flipping Physics Calculate the altitude of a satellite in geosynchronous orbit or geostationary orbit. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:11 What is geosynchronous orbit? 0:47 Drawing the free body diagram and starting to solve the problem 3:02 Solving for the satellite’s angular velocity 4:05 Identifying the masses and radii 5:25 Defining “r” and solving for altitude 6:29 The physics works! Multilingual? Please help translate Flipping Physics videos! Previous Video: Deriving the Acceleration due to Gravity on any Planet and specifically Mt. Everest Please support me on Patreon! Thank you to Aarti Sangwan and Christopher Becke for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video. Altitude of Geostationary Orbit (a special case of Geosynchronous Orbit)
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Altitude of Geostationary Orbit (a special case of Geosynchronous Orbit)
Flipping Physics posted a video in Circular Motion & Gravity
Calculate the altitude of a satellite in geosynchronous orbit or geostationary orbit. Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:11 What is geosynchronous orbit? 0:47 Drawing the free body diagram and starting to solve the problem 3:02 Solving for the satellite’s angular velocity 4:05 Identifying the masses and radii 5:25 Defining “r” and solving for altitude 6:29 The physics works! Multilingual? Please help translate Flipping Physics videos! Previous Video: Deriving the Acceleration due to Gravity on any Planet and specifically Mt. Everest Please support me on Patreon! Thank you to Aarti Sangwan and Christopher Becke for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video.
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Provoke not the ire of I. Quick to temper, quick to wit. Verily I see the serpents' lie, perch'd low to befit. Bade not beget a quarrel but beget one indeed. Riven from I alike a valley cleft. Oft I wonder'd my words would have heed but I discover'd a friend bereft.

I hope your bike serves you well for some time to come. also your tone in the beginning was a bit harsh, but I digress. Overall this blog was very nice, I think gear ratios are cool and they really are closely related to angular momentum> I remember learning about gear ratios in Principles of Engineering last year.

Two words, ten letters: gun on rails

I totally missed out, did not I?

How come I was not invited?

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 unitoftime 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.
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The concept of moment of inertia is demonstrated by rolling a series of cylinders down an inclined plane. Visit physicsworld.com for more videos, webinars and podcasts. http://physicsworld.com/cws/channel/m...

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Video Discussion: Walter Lewin Demonstrates Moment of Inertia
FizziksGuy posted a topic in AP Physics C
Name: Walter Lewin Demonstrates Moment of Inertia Category: Rotation Date Added: 20171205 Submitter: FizziksGuy The concept of moment of inertia is demonstrated by rolling a series of cylinders down an inclined plane. Visit physicsworld.com for more videos, webinars and podcasts. http://physicsworld.com/cws/channel/m... Walter Lewin Demonstrates Moment of Inertia
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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.

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 offcenter 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.

The Engineering design process is a series of steps that engineers go through to create a product of some sort. The process can be very repetitive at times while going through a process of trial and error. The lab that we did in class demonstrated the engineering design process. We were given two paper plates, six pennies, a pencil, and tape to create a spinning top. First we came up with an idea that we thought might work so we constructed a top that had a pencil through the center of a plate with six penny's evenly spaced around the plate but not to the edge. The plate was at about the center of the pencil. This failed because the plate was not stable enough on the pencil so we added the other plate to the bottom of the first plate to stabilize it a little more. We also lowered the location of the plate to be more toward the bottom of the pencil. This would decrease the wobbling because there would be less torque on the pencil if there is a smaller distance since Torque is the cross product of F * r. These two adjustments improved the top but it still was not spinning perfectly. Something that would have made it spin a lot better would be to shorten the length of the pencil. This would have gotten rid of the weight at the top of the pencil to decrease the net torque even more. Moment of inertia was a big part of this lab because moment of inertia is an object's resistance to rotational acceleration. An object with the least possible moment of inertia would be the most successful. Angular momentum was also a very important part of this lab because angular momentum describes how difficult it is to stop a rotating object. Therefore, an object with the greatest angular momentum would be very successful in this lab because it would take a lot of torque to change it.

The 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).

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.

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

Video Discussion: Deriving the Acceleration due to Gravity on any Planet and specifically Mt. Everest
Flipping Physics posted a topic in Video Discussions
Name: Deriving the Acceleration due to Gravity on any Planet and specifically Mt. Everest Category: Circular Motion & Gravity Date Added: 20171211 Submitter: Flipping Physics Derive the acceleration due to gravity on any planet. Find the acceleration due to gravity on Mt. Everest. And determine how much higher you could jump on the top of Mt. Everest! Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:08 Deriving the acceleration due to gravity on any planet 1:54 Finding the acceleration due to gravity on Mt. Everest 3:16 How much higher could you jump on the top of Mt. Everest? Next Video: Altitude of Geosynchronous Orbit (aka Geostationary Orbit) Multilingual? Please help translate Flipping Physics videos! Previous Video: The Force of Gravitational Attraction between the Earth and the Moon Please support me on Patreon! Thank you to Aarti Sangwan and Christopher Becke for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video. Deriving the Acceleration due to Gravity on any Planet and specifically Mt. Everest
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Deriving the Acceleration due to Gravity on any Planet and specifically Mt. Everest
Flipping Physics posted a video in Circular Motion & Gravity
Derive the acceleration due to gravity on any planet. Find the acceleration due to gravity on Mt. Everest. And determine how much higher you could jump on the top of Mt. Everest! Want Lecture Notes? This is an AP Physics 1 topic. Content Times: 0:08 Deriving the acceleration due to gravity on any planet 1:54 Finding the acceleration due to gravity on Mt. Everest 3:16 How much higher could you jump on the top of Mt. Everest? Next Video: Altitude of Geosynchronous Orbit (aka Geostationary Orbit) Multilingual? Please help translate Flipping Physics videos! Previous Video: The Force of Gravitational Attraction between the Earth and the Moon Please support me on Patreon! Thank you to Aarti Sangwan and Christopher Becke for being my Quality Control Team for this video. Thank you to Youssef Nasr for transcribing the English subtitles of this video. 
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.

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, RK


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View File SimuLAB: Motion in a Circle Interactive simulation lab activity where students explore quantities describing circular motion. Submitter FizziksGuy Submitted 11/30/2017 Category UCM & Gravity

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NEW FILE: SimuLAB: Universal Gravitation APlusPhysics Simulation
FizziksGuy posted a topic in Honors and Regents Physics
View File SimuLAB: Universal Gravitation APlusPhysics Simulation Interactive simulation to explore the basic relationships in Newton's Law of Universal Gravitation using Geogebra. Submitter FizziksGuy Submitted 11/29/2017 Category UCM & Gravity
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