Modeling Acceleration

Physics homework for 10/21/14:

Tuesday, October 21, 2014

Tue Oct 21 - "Modeling Acceleration" Blog Post

Find a picture of a model of acceleration online. Provide the link to the model and explain how it shows acceleration.  Is it a good model? How can you tell the difference between different accelerations with this model?

Today in our physics class we modeled acceleration in three ways. We modeled it through a formula, a strobe diagram, and a graph; specifically a velocity vs. time graph. Some variables like velocity can be modeled this way, but not all variables I believe. Strobe diagrams specifically show the motion of an object, formulas show the relationship between certain variables to achieve a specific answer. It also models acceleration through numbers and operations. Graphs model acceleration by plotting out data to show a progressive acceleration. 

Now, I will explain the first acceleration model only. I posted the other acceleration models just for reference. Also, side note just in case anyone needs help (I doubt you guys do need help with it though since you're all smarties): if you want to post a picture in a blog post and have it show in your post you need to either click the little picture icon that shows up while you are typing the draft of your post (the icon highlighted in yellow is the little picture icon in the picture I added below this paragraph). Click it and you should be able to navigate from there. If not, Google's your best friend guys, Google will always help (or I will try and help if anyone wants to ask :D).

OR just click on your photo, but don't let go of the button. After that, continue to hold down on the button and drag it to your Blogger post tab and drop it in your post. This works best on a laptop or a computer - not a mobile device. Basically go to Google, find a picture, click on the picture and hold the button down, drag the picture to your Blogger tab, and drop it in the text box where you type your post.

Okay, now onto the actual physics! 

Let me copy the top photo down here so you guys can see it better 

Sweet, huh? This model shows acceleration through a strobe diagram. It does so by drawing the running girl relative to each part (a,b,c, and d). By "relative" I mean the artist drew the girl at a specific position in the model to match up with the other pictures in the model. Plus, while a and b don't necessarily show true acceleration and more so show the girl starting and running at a constant velocity, parts c and d show velocity by showing the girl at different and not constant positions. The girl is accelerating and acceleration deals with a change in speed and/or direction. The girl's speed isn't constant here so it changes! How do we know? Each part of the part doesn't show her moving the same distance each time, she changes her speed each time therefore changing her distance. For example, in part c the girl runs a bit forward, then a little more than that, and then a lot more than that, and so on and so forth. And the strobe light takes photos at a constant rate, it will flash however many times in a certain amount of time consistently so it captures how much the girl traveled in a given amount of time consistently and not randomly.

Okay so it shows acceleration, who says it's a good model? Well, I say it's not a bad model. Maybe it's just me, but even though the diagram looks relative to each picture, it doesn't look entirely relative. For example, the girl's starting position looks a tiny bit different in each photo and the figure doesn't meet up too well when you compare it to some positions in the photos. But it might be me, either way it's generally a good model showing acceleration, and you don't necessarily need relativity to model acceleration. It might be more accurate, but I mean either way picture c and d both show acceleration nonetheless. They are also good because they fit what we have been doing in class, they look like our models just with a person instead of a vehicle and Ms.Reid is most likely looking for this. Plus her models are awesome in my opinion. This model is also good because it shows a change in velocity throughout a similar period of time. And it shows different types of acceleration (negative, positive, and constant but I don't think b counts since her direction nor her velocity changed). It also shows something we can relate to or easily visualize and remember. Say I'm in class even and I need to remember acceleration visually because I'm a visual leaner, well I could think of me running to maybe a busy street or maybe me running away from a rabid zombie and remember acceleration. Or I could imagine cars zooming away or slowing down. Either way it is quite a good reference. The model also kind of shows the movement of a person in front of, say, a motion detector, and we could picture what the graph would look like. Plus, it's very simple and very easy to replicate. Sweet and straight to the point.

Now, how can I tell the difference between accelerations with this model and even in this model when I mentioned different types of acceleration? Simple, I just look at the distance between each position and see how they compare like all of you smart cookies.

For example, in part c I see that the girl didn't move much between her starting position and her succeeding position (her next position). But then from her second position to her third position she moves a bit more forward. And this goes on and on with her moving more forward each time. I realize that this is positive acceleration because she is going a farther distance within the same period of time each time meaning she is picking up her speed. And that's true, right? If I cover more distance in say one second than I did before in the same amount of time I'd be picking up speed. I can't travel more if I go the same speed or a slower speed.

And part d shows her going at a negative acceleration because she slowly covers less distance within that time. If she covers less each time she's losing speed. I can tell the difference between these two accelerations by noticing how her distance changes each time. This will help me point out different types of accelerations when I look at other diagrams too because I'll know to look at the distance covered and to observe how she is speed-wise.

Let's all turn into bunnies!! (Just kidding).

Good night everybody :DD!!

--Ooviya

Acceleration

Physics homework for 10/20/14:

Mon Oct 20 - "Acceleration" Blog Post

A sports car and a school bus are stopped at a traffic light.  Use your physics vocabulary words (correctly) to completely explain the differences and similarities of the motion of these two vehicles as each goes from a stop to the speed limit of 30 mph.  Also describe the differences and similarities as they stop at the next red light.

Monday, October 20th, 2014

                        Acceleration: School Bus Vs. Sports Car

Today in class we learned about acceleration and compared it to some other variables. This blog post will mostly be about a sports car and a school bus, but before I get into that, what is acceleration? Acceleration is the opposite of constant velocity which is velocity where the speed and direction remain the same. So the rate of the speed is steady and the object is only traveling in one direction. If acceleration's the opposite of constant velocity, you can guess that acceleration does NOT remain the same some where. And you are right! With acceleration, the velocity changes, the direction changes, or both change! Acceleration is also a vector quantity meaning it has magnitude and direction. The formula for it is change in velocity over change in time and it is measured in m/s^2. There can be negative acceleration and positive acceleration, basically it is when something is speeding up or slowing down. 

Now, let us talk about sports cars and school buses!

Let's say a school bus and a sports car are at a red light and once the light flashes to green the vehicles zoom off at 30 mph. And let's say they stop after a while at another red light. There is a lot of physics involved there, so let's analyze the physics. First, we'll observe the differences and similarities of the motion of the vehicles when they are traveling from the first red light at 30 mph. Then we will look at the similarities and differences of the vehicles from their 30 mph to the next red light.

To begin, at the first red light the vehicles are at a COMPLETE stop with a speed and/or velocity of zero. Same for the acceleration. The vehicle will be displaced from this position as it travels forward and away from the red light. So the red light switches to a green light and these vehicles zoom away. Now, the sports car might reach the limit faster than the bus due to how it runs, so its motion will most likely be faster than the school bus at most times. The sports car will have a positive acceleration, increasing its speed and/or its velocity until it reaches 30 mph. The car's velocity is most likely NOT constant at it might rev up its engines and jet off super fast at a nonlinear rate, but eventually it might need to slow down to stay close to the speed limit. So the car might have a negative acceleration at times. The car might change its direction while driving too, not just its velocity. The car might need to take a sharp turn and/or speed up or slow down. And it will be displaced a certain amount from its original position THOUGH, if the car is swerving around the damn neighborhood looking all fine and fresh then it might not have been displaced much at all since the car may not be far from its original position any more. So any ways, while this car is traveling, trying to keep a constant velocity of 30 mph (but possibly not necessarily always at 30 mph), the school bus might be farther behind because it needs to accelerate positively. School buses might take longer to really speed up, so the velocity might accelerate much more gradually than compared to the sports car. And since the velocity is changing and not remaining constant it is accelerating, unlike constant velocity. The bus slowly builds up its velocity to 30 mph and it might be farther behind than the sports car, but generally both vehicles are trying to keep a constant velocity of 30 mph forward. They will probably both have to accelerate positively and negatively just to remain within the limit or just near it. And they are usually going forward or taking turns around streets because school buses need to drop off kids and kids live in various neighborhoods and sports cars need to pick up chicks - you know, for the farm nearby the playground :^). The school boys love chicks :-D - why are you staring at me like that? D:

Any ways, moving on! 

So these two awesomely cool vehicles are nyooming down the streets trying to keep a constant velocity and they are nearing a stop light. The sports car will have to punch the brakes so that it just doesn't zoom past the traffic lights. The sports car can probably negatively accelerate quickly though and bring itself to a stop. So the acceleration would have negatively gone down due to the velocity changing, the velocity decreased and the time increased. The bus will negatively accelerate as well to a slow stop, it can probably stop better than the car due to its acceleration rate compared to the car. The velocity goes down until the bus stops. The main difference is that the car in general traveled faster (accelerated) than the bus. The car need to negatively accelerate fast enough in contrast with the bus and it probably reached the stop light faster than the bus due to its velocity. It probably had a much less constant measure of speed than the bus. On the other hand, both vehicles did negatively accelerate to a stop and had their velocities go down quite a lot. The bus might not stop first, or it might, but either way both vehicles slowed to a stop by changing their acceleration. 

Any ways, that is my take on the acceleration topic of buses vs. sports cars. But good luck to Ms.Reid with her work, she probably has some stuff to catch up on so I hope it goes well ;^;7. 

Sucky blog post as usual, but buenas noches mi amigos :33 <3 .

Have science ponies!!!~~

GUESS Method

Physics homework for 10/09/14:

“GUESS Method” Blog Post - List the 5 steps of the GUESS Method. On each step explain it in your own words and describe what you used to do for this part when doing a written response question.

Thursday, October 9th, 2014

  GUESS Method and Responding to Questions

        Today in class we discussed the "GUESS" method. GUESS is an acronym here, but we took notes about it and demonstrated as well as explained how to use GUESS. We also reviewed some variables by doing a worksheet involving questions about the variables.

GUESS stands for something since it is an acronym; each letter stands for one word, and the method is used for solving problems as best as we can. It is a way to readjust our strategies. Essentially, it will help in many classes, not just physics. But it is mainly for our physics problems.

Any ways, here is what GUESS stands for and here are the steps with an explanation:

G - Stands for "given." By "given" it means what is given or stated to you that is important in the question. Usually it is numbers or variables. For example, here's a physics problem that might help us understand "G" better:

Lucy was getting ready to go to school. Her school is 1000 meters away from her home. She starts from home towards her school. About 200 meters in realizes that she forgot something and walks back home. Once she gets everything, she goes straight to school. This all happens in the span of 25 minutes (1500 seconds). What was her total distance?

With given you should state the important information in the problem that will help you solve the problem. And make sure you include your units and variables! Those are important as they help you answer a specific question better. Don't screw yourself over by missing a tiny description, you deserve those points after you do all of that work.

In this problem you want to get the numbers, units, and any other important details because that will help you solve this problem. And you don't need to focus on unnecessary information because it won't help you solve the problem, the scenarios just help you get the idea of things. It doesn't matter if Lucy or Billy-Bob or whoever was going to school or something really, it's the information (sorry Billy and Lucy...Still love you!)

So here is what you would take note of for your given: 1000 meters, 200 meters, 25 minutes (1500 seconds), d 

With this kind of a question you want to be careful. While the extraneous details are not entirely important they still describe everything and you might miss something if you ignore everything entirely. I even left out another "200 meters" because even though she walks back home it wasn't stated so I didn't list it, but it's in my head and I will note it down some where else if not here.

U - Stands for "unknown." "Unknown" as in what is the question? What does the question want? In physics it is usually the variable you want to find, but in general it clarifies questions and that is SUPER important in answering questions because if you don't get the question you might not answer it properly and it might confuse you more than you'd want. 

For the unknown, you would write the question down some where and the variable it is asking for if it is physics problem about variables. And write notes about the question if you need to, if it helps then it's all good. The whole point is to better solve questions in an easy way. You would write for this problem "d = ?" or "what is the total distance traveled?"

E - As in "equation." For this step, you would identify the equation you need to utilize to figure out the answer to the problem. Sometimes you need to rearrange your formulas to find what you are looking for. For instance, if you need to figure out delta time and you only have the equation for speed/velocity/etc. you will have to isolate delta t by using algebra, the triangle method, or cross-multiplying. 

(Algebra: s = d/delta t [divide d on both sides to get d/s = delta t]

Triangle method = Write your formula out with your data plugged in and draw a triangle around the formula once you've got three numbers. Section off each and move one number to the top of the number on the other side

Cross multiplying = Set up your data as two fractions, making sure that they are in a relative and not random order. Multiply the first top number by the second bottom number and the second top number by the first bottom number. Finally, divide both sides by the appropriate number to get your answer).

Lucy's problem requires distance which is easy to figure out, you do not even really need an equation here. But you could use one nonetheless. Here I would add all the distances she traveled. But let's identify an equation just for this post:

d = s x t 

Since I didn't give her speed you would have to figure that out so maybe add in the speed equation and variable for your other parts and for this part. Her speed is .93 (repeating three) m/s though.

S - Is for "substitute." Here you would take your important information that you noted and plug it into the equation you wrote down. So put all of your information into the correct places. All of the meters would go in the place of distance or "d", the time would go where "t" is, the speed would take place of the "s." And make sure to include your units, you might not answer correctly without them. Even the units go through some math!

In the problem above, you could just add all of her travel to get your final answer, but let's pretend it is required that we use the equation.

Her speed is .93 (repeating 3) meters/seconds times 1500 seconds. So change "s" to the speed I just wrote with the units and "t" to 1500 seconds and bring down the d. You should get this:

d = .93 (repeating three) m/s x 1500 seconds 

Now... Finally...

S - "Solve"! Yeah, you can guess what this step is about *sarcastic laughing inside of my head*. Basically you do the math here, you go through with your operations and what not, making sure to include all units and info! So just do what the equation asks for and simplify it until you have your answer. Sometimes you might need to add some more steps in on your own to get there. You answer will be in this form: "variable = number + unit" (yay, an equation!)

So d = .93 (repeating three) m/s x 1500 seconds = 1400 meters (I skipped the actual multiplication and did it on a calculator, but you would do the multiplication out if you didn't have a calculator).

And that is what GUESS is! That is what GUESS makes up! It helps us easily maneuver through a problem. You don't always need it, but it can really help either way. And it goes over something we learn in physics, how to properly use equations and stuff. It teaches us about math and science a bit in a way too, it's pretty cool.

But I haven't always used GUESS so what did I do before?

Well, I didn't do things in a completely organized way, but I did apply my skills and what not.

First I read the question multiple times to really hammer the point in (unless it is simple, then I read it twice and once when I'm done). Next I pay attention to my numbers and highlight them somehow. Then I clarify the question. After that I use whatever I've been taught like an equation or something to figure the problem out. Now, I don't always show every detail and skip steps, but it's not always. For example, with the Pythagorean theorem if I know the squares of the numbers I might just instantly write the squares down and not something like "4^2". Finally I just do the math and add the units in. I did something similar to GUESS, but I was not as organized, I did things instantly. GUESS might not apply to everything either - but it does go over most of what you should do when trying to solve a problem! 

Sometimes I might even have to remember a formula or mentally figure out what a formula is when I need it. 

I would also double-check and make sure of everything completely afterwards, but it varies.

But good evening everyone!

Speed and Velocity

Physics homework for 10/08/14: 

“Speed and Velocity” Blog Post - Write your own definition of speed and velocity, highlighting the difference between the two. Describe an example of both average velocity and instantaneous velocity in your own life (not one covered in class)

Wednesday, October 8th, 2014

                         Speed and Velocity 

       Today in class we mainly took notes, did some velocity problems, wrote some definition down, and we also discussed and reviewed everything together. We mainly learned about equations and velocity today, we also talked about variables and what not. And we illustrated some key points about some things like equations.

       

Moving onto some definitions though, speed is the rate of distance covered in a given amount of time and velocity is speed with a direction - but these are the notebook definitions! In my own words, I would define speed as how fast you are traveling in a certain length of time. Or maybe I would describe it as the rate you are traveling by depending on your distance and your time or as the rate at which an object covers a certain distance/how fast something is moving. As for velocity, I would basically call it the rate at which something is traveling by depending on distance and time, but with a direction, whether the direction is a loop-de-loop or just a simple north or even a southwest or something velocity has direction. 

Now, because velocity has direction and magnitude (size) it is a vector quantity. Since speed has only magnitude it is a scalar quantity. We have not talked much about these things yet, but we will probably delve into them soon.

Velocity and speed are quite similar, but also quite different in many ways, here are a few ways in which they are similar:

*Speed and velocity both use t and a delta.

*They both usually require you to find the difference between something final and something initial.

*Both equations require division.

*The units for both are m/s. 

*Both have speed or a rate at which they are going.

While both speed and velocity have similarities (many more than I have listed), they also have differences.

Here is a list of some of the differences:
~Velocity has direction unlike speed, therefore it is a vector quantity. And speed is a scalar quantity.

~There are a few types of velocity (instantaneous and average) and apparently not many types of speed. But basically both of them have different sub-divisions.

~With speed "d" (distance) is used in the equation to find speed and "s" is used as well. Whereas with velocity "v" (velocity) is used and "delta x" (change in "x"). And notice an "x" is used; not a "d", even though "delta d" would most likely be the same thing as "delta x." 

~In velocity you have to find the displacement of whatever is moving, on the other hand with speed you are given a distance and just need to plug it into the equation.

Those are the main differences I can think of, but there might be a few more.

Real Life Examples of Velocity

Moving on to the types of velocity we have learned about. Along with the notes and what not we also learned about instantaneous and average velocity. Average velocity is the velocity over a given period of time. Basically it is your velocity when averaged. 

So let's say a truck is zooming by, the truck has velocity but it is not the same the whole way through. Since it is not the same the whole way through you would try and find the average velocity of the truck by taking a few different individual velocities on the truck's journey and averaging them. Or even just two velocities. You would probably do this by combining (or maybe subtracting velocities) and then dividing by the number of information.

Instantaneous velocity is easier to figure out, instantaneous velocity is the velocity at any given moment in time or at any instant. Let's go back to that truck, let's say some time in on the truck's journey the truck's velocity is something like this: "# m/3 (direction)" - in that instant, that would be the truck's instantaneous velocity. At this very moment, some cars on the road might have instantaneous velocities that are above the limit. And also at this moment a car might have one velocity and then a different velocity later on. Depending on the instant, that is your instantaneous velocity.

An example of both velocities in my life are here:

>Average velocity: When I run some where like say down a hallway my velocity does not stay the same and usually I would focus on my average velocity. I do not run the same rate the whole time so I would take a few of my velocities while running and divide it by the number of information to get my average velocity. I would also take note of the direction.

Also, sometimes when dancing the velocity of my movements change (if that counts). And while someone drives their velocity changes.

Maybe riding a bike or something can also represent average velocity. I don't ride a bike any more, but I definitely did ride one a lot when I was younger.

>Instantaneous velocity: In my own life I guess when I use the treadmill I take note of my instantaneous velocity. Or I at least show instantaneous velocity. The reason why is because at a given moment you usually have your settings at a certain speed and what not. So for 10 minutes I could be running at the fourth speed reaching a distance of half a mile or something. Once the velocity is solved for that would be the instantaneous velocity for that one moment.

Plus, with each of my activities like biking, running, or dancing instantaneous velocity would be one instant from each of those. Unlike average velocity, you are only focusing on one given velocity at one given moment in time.

Also, here are some graphs of velocity and speed: 

And also here's how to use the equation for speed and velocity:

s = d/(change in t) and v = change in x/change in t
s = 2000 m/100 s          v = 100 m - 0 m/ 50 s - 0 s
s = 20 m/s                      v = 100 m/50 s
                                       v = 2 m/s (+ a direction)

But enough of my blab, good night everyone :33.

  

Distance vs. Time Graphs

Physics homework for 10/07/14: 

“Distance vs. Time Graphs” Blog Post - Describe what we did in class today and explain why you think these graphs would be necessary in our science class.

Tuesday, October 7th, 2014

Distance vs. Time Graphs Lab

          Today in physics class we finished our "Distance vs. Time Graphs" lab from yesterday. The lab involved graphs (specifically distance versus time) that we had to replicate on a computer program using a motion sensor that tracks and plots data. We were also asked to explain how we created the replicas of each graph, so we had to describe our movement near the sensor. Did we move backwards or forwards? Did we have to go fast or stay still for a while? Was our graph positive or negative? Etc.  And we had a total of seven graphs to work with. Also, some questions were answered about the graphs' characteristics and we played a little game where we had to match a different graph by trying to recreate the graph with our own movement near the sensor.

                 These types of graphs would be necessary for a science class, especially ours, because in physics distance, time, speed, acceleration, velocity - all those things are big focuses in a physics class, and most of the time those things require graphing to display your data. And in science data is a crucial key to proving your point and what not. We want to record things like distance and time to get a better idea of what we are focusing on. Plus, in physics we will constantly be exploring new focuses and all data will be accounted for with each focus. And the data will usually be graphed.

        

          Distance vs. time graphs are also really main graphs since most of the things people study in science involve distance and time, even if you are learning about something else. They are necessary to show our mathematical skills too. And showing your knowledge on trend lines and what not is key to prove points and understand things better, it also makes things easier in a science class.

          

          We also might be focusing a lot on motion for our first part of the year and most motion topics involve things like speed and what not, so representing what we are learning is important too. And maybe most of our labs and stuff will involve moving things so distance vs. time is easy to graph for such labs. Plus these graphs personally help me better understand the relationship of d and t and they give a good idea about the distance and time of things. I mean I can look at a graph and think "ah, if x is increasing and y this thing is doing this" or "this thing is doing that."

          Most things in physics and science in general have motion and graphs represent the journey of those objects, comparing the journeys can help illustrate differences between certain things like say distance and displacement or velocity, speed, and acceleration.

         Maybe it is on the MCAS/PARC and so it is vital that we learn it. Maybe it is important that we show the relationship between the things being graphed or maybe representing data in various forms is important in a science class. Possibly it shows a lot of good logic which is huge in science. It could be all of this, but I know that "___ versus ___" graphs are common and important in generally all science classes. Last year we had graphs to show change in temperature over time and we did that to add onto our study of heat transfer. This year we might need to show change in x vs. y to add onto our focal points of study. 

       To add on, the graphs show a change in y/x and can be represented in many ways, plus most of the things we measure have variables in science if not all.

       In science we want to better understand our world and the science of it and since these graphs kind of relate to real life scenarios it might help us get a better understanding of some real life situations and it might help us in the real world. And science is usually all around us. I know that knowing small things like "hot goes to cold" helps me because then I can logically try to figure something out to get warm or cold. Maybe it is the same with these graphs since classes prepare us for bigger things - not just tests or something.

    Regardless, these graphs can be very useful and are going to be most likely used a lot in our class and are probably used in many other science classes.

--Buonasera :3 <3 

("Pfft! Screw gravity! >U *levitates into the night*")

--Ooviya =^w^=