Questions

Guys I have a few questions for all of you.

1) How often do you guys come and look at the blog?
2) What was your motivation to come read the course blog?
3) How often do you comment on posts?
4) What motivated you to comment on the blog?
5) Has reading the blog and commenting on it helped your intrest in the course?
6) If yes, how?
7) Has the blog made you feel more confident in physics?
8) If yes, how?
9) What was your favorite blog article?
10) Do you feel that knowing Jared and myself helped you to comment on the blog more often?

"Humans vs. Zombies" - the math

I hope someone is taking down data of this "Humans vs. Zombies" game to see if it matches the mathematical model.

3D Films "How do they work?"

Although most of us have experienced a 3D film at least once in their lives, many do not understand the science of how the cinema industry manages to project a 3D image from a 2D screen.

When viewing an object in real life, the left eye sees a bit more of the left side of the object while the right eye sees a bit more of the right side. Your brain then combines the two images, allowing you to see the full 3 dimensional effect.

To simulate this theatres use polarized light, or light waves that vibrate on only one plane. Although most forms of light that we see is unpolarized, they can be converted into polarized form using a polarizing filter. These filters have tiny lines etched into them that allow only light vibrating on the same plane as the lines through.

Duringthe filming process, the film is recorded useing two cameras set side by side to simulate the left and right eyes. Then, the cinema will project the two slightly different images onto the big screen, but they will use to different polarizing filters on the cameras. The two seperate, now polarized, images will then reflect off of the screen back onto the audience who will be wearing polarizing glasses. These glasses will only allow the left image to pass through to the left eye and the right image to pass to the right eye, fooling the audiences brains into "seeing" an image as if they were actually there.

The FULL slinky drop story!

Enjoy! http://arxiv.org/PS_cache/arxiv/pdf/1110/1110.4368v1.pdf

Proof Techniques

Unfortunately, in order for something to be generally accepted as fact it must be proven, meaning that it must be shown to be true for all cases. However, the most commonly used ways for proving things are usually inadequate, being that they rely on the truth instead of more convenient techniques. For the sake of simplicity, here are a couple of more practical methods to prove things.

Proof by Blatent Assertion:

Use words and phrases like "clearely", "obviously" and "as any fool can plainly see..."

Proof by Intimidation:

This can be useful for physical as well as abstract assertions. For example, "you better believe this if you know what's good for you" is a good argument if you are in a position to use your suppior strength to subdue your opponent, like a younger sibling or small animal...

Proof by Interuption:

Just keep interrupting until your opponenet gives up.

Proof by Misconception:

An example of this is "2 equals 3 for very large values of 2". Once introduced, any conclusion is reachable.

Proof by Confusion:

Your argument should be arranged into ciruclar patterns of reasoning. If your feeling creative, try to arrange it in more complex patterns, such as figure 8's.

If used correctly, you should find it incredibly easy to raise and defend any statement you wish. Can you think of any different types of proofs that I might not have stated? Also, can you add to or revise any of the proofs listed?

http://www.jyi.org/resources/humor/proofs.html

Flying Deer

An occurrence which seems to be happening at many runways across the United States both commercial and private. No, it is not reindeer taking off and landing but deer being stuck by airplanes. This seems to be an issue happening around the country and I would like to know why?


In 2009 at the Charlotte Douglas International Airport a U.S. Airways flight was landing and shortly after touching down there was a jolt in the plane. Passengers described it as hitting a giant pothole in the middle of the runway. After the fact the pilot came over the intercom and told the passengers that they had hit a small deer. In this situation it did not do any damage to the plane itself but what would happen to a smaller plane.


As one of our own JU Dolphins found out last fall it does a considerable amount of damage to small Cirrus. On his first night flight ever during his flight lessons Sean Carney was landing his Cirrus at Cecil Field. As he landed his was not just a small jolt. Describing the situation Sean said "Typically when you are landing you feel two bumps, the back wheels touching, the front wheels touching and that is it. But on this one I felt three bumps." The third bump was the propeller of the airplane hitting the deer. This plane did not get out as scotch free as the large jet.

This shows the side of the plane after the impact and how much of an effect the deer left. Later that night the National Guard at the airport had to go out and shoot two more deer because they would not leave.

Now as I stated at the beginning, I would like to know why these deer all seem to congregate around airports and a lot of the time the inevitable happens?

"Quantum Locking"

On October 16 some researchers at Tel Aviv University in Isreal uploaded a video of them demonstrating what is known as "Quantum Locking", or in non-scientific terms, making things hover in mid-air.

Here's a link to the video: http://youtu.be/Ws6AAhTw7RA

Even though to most of us this seems like something strait out of a sci-fi film, it is apperently not as complex as it would appear.

To begin, the researchers started with a crystal sapphire waffer and wrapped it with a thin ceramic layer of yttrium barium copper oxide. While this ceramic layer ordinarily has no particularly distinguishing features, when cooled below -185 degrees celcius it becomes a superconductor. The final result is a frozen disc.

When placed over a magnet, the superconductor and magnet would normally repel each other. However, because the ceramic layer is so thin, some of the magnetic force is allowed through the disc at certain weak points in the ceramic layer. Now, these paths of magnetic force through the disc are called flux tubes and are the secret to the researcher's little levetation trick.

Because there are several flux tubes throughout the disc, the flux tubes will try to remain as stationary as possible. This creates a 3D locking effect, which is what the researchers demonstrate.

Here is a link to the researcher's explanation of their demonstration. http://www.quantumlevitation.com/levitation/The_physics.html

On Tuesday, October 4, the Royal Swedish Academy of Sciences awarded 3 astrophysicists Nobel Prize in Physics. By studying the most distant supernovae known to man, Saul Perlmutter, Brian P. Shmidt, and Adam G. Riess discovered that not only is the universe expanding, but the expansion is also accelerating at a constant rate.

However, the two physics teams could not just study any regular supernovae. They had to study a particular type of supernovae, called a Ia supernovae. These incredibly powerful explosions can emit as much light as a whole galaxy, meaning that, hypothetically, they should be of a particular brightness despite being so far away.

In total, the two teams found over 50 distant supernovae, each of them whose light was weaker than would have been expected. The conclusion that both teams reached was that, had the universe's expansion been constant, the teams would have been able to accurately predict the brightness of the supernovae. Therefor, because the stars were dimmer than expected, the universe's expansion is constantly accelerating.

With this new information, do you think it will ever be possible for humanity to know what lies beyond the edge of the known universe?

Here is another online article to the Nobel Prize in Physics.

Free Body Diagrams

Class, if I may call you that. I have been informed that many of you are struggling with free body diagrams recently. I can relate because when I first started learning about them myself I struggled to wrap my head around the concept. Now what I do might seem strange to some of yall however it works for me. What I do is envision myself as the object listed and imagine all of the forces acting on me. It might seem weird but try it sometime it will work. I know Dr. Lane likes when you draw a representation of the object but I also like to use squares it helps to give a better scale on the vectors direction. These free body diagrams help to calculate forces in Newtons Second Law because they show you the magnitude and direction of the forces. In seeing this what you have to do is find the x and y components (try rotating the force to get a vertical and horizontal force line, it helps) then just add them like vectors to find the net force. Let me know how all of this works for you.

VonHayes

P.S. Try looking at this website some time, it divulges a lot of helpful information, http://hyperphysics.phy-astr.gsu.edu/hbase/HFrame.html

The Laws of Physics Reexamined

We all know about the Laws of Physics and how they invariably govern the way the various bodies of the universe interact with one another. These laws are considered unbreakable until proven otherwise.

But are they really?

Thanks to the meticulous recordings of Warner Brothers ® characters such as Buggs Bunny,
Pepe Le Pew, and Wile E. Coyote, newer laws have been under careful review and examination.


The Cartoon Laws of Pysics


Law I) Any body suspended in space will remain in space until made aware of its situation.


Law II) Any body in motion will tend to remain in motion until solid matter intervenes suddenly, stopping the body completely.


Law III) Any body passing through solid matter will leave a perforation conforming to its perimeter. The threat of skunks or matrimony often catalyzes this reaction.


Law IV) The time required for an object to fall twenty stories is greater than or equal to the time it takes for whoever knocked it off the ledge to spiral down twenty flights to attempt to capture it unbroken.


Law V) All principles of gravity are negated by fear.


Law VI) As speed increases, objects can be in several places at once.
This is particularly true of tooth-and-claw fights, in which a character's head may be glimpsed emerging from the cloud of altercation at several places simultaneously. This effect is common as well among bodies that are spinning or being throttled.


Law VII) Certain bodies can pass through solid walls painted to resemble tunnel entrances; others cannot.


Law VIII) Any violent rearrangement of feline matter is impermanent. They can be decimated, spliced, splayed, accordion-pleated, spindled, or disassembled, but they cannot be destroyed.


Provide an example of the above laws that you have personally witnessed.
(I'm talking about what you've seen on TV, not in real life...)

Whats up with those wings?

Hey blog, first off I would like to appologize for the delay in posting a blog. Now to the meat of the blog. So two weekends ago I flew to Cincinati with my girlfriend and on the flight up had a question pop into my head. I was flying on one of the smaller regional jets an Embraer 170 and I was next to the wing. What I noticeced on this plane and I have noticed on other smaller planes before it the 90 degree turn of the wing right at the end.

My question for all of you is why do we find this turn up in the wings? Is its just to look cool or does it actually serve a purpose?

Mapping g on the moon (and earth!)

http://www.npr.org/2011/09/10/140361610/nasa-launches-probes-to-study-moon describes a recently launched unmanned NASA mission to the moon to map out the moon's gravitational field. What is the gravitational field? It's quite simply the acceleration due to gravity ("g" as we've been calling it in class) as a function of position around the moon!

On the surface of the earth, g is a pretty consistent 9.8 m/s^2, but it does vary depending on your position on the planet, since Earth is not a perfect sphere. And once you start to get out into space, g begins to diminish drastically, dropping off like 1/r^2, where r is the distance between you and the center of the earth!

The moon's acceleration due to gravity behaves much the same way. On the surface of the moon (at least the parts we've been to!), it's about 1/6 of our g on earth (so about 1.7 m/s^2, give or take), and also drops off like 1/r^2 (where r is the distance between you and the center of the moon) as you leave the surface.

These probes will measure these variations in the moon's g as they orbit on opposite sides of the moon! By the way, the GRACE mission (http://www.csr.utexas.edu/grace/) did the same thing on earth! Here's a map of the results, depicting the difference between the local g and the average g: http://www.csr.utexas.edu/grace/gallery/gravity/03_07_GRACE.html, where the red regions represent a higher value of g and the blue regions represent a lower value of g (measured in units of "milligals," which are named after Galileo; 1 gal = 1 cm/s^2).

Throwing a Baseball

So, we all understand the concept behind throwing a baseball. Palm the ball with a firm, but not too hard grip, then throw it with as much force possible at the catcher. In proffesional games, and even on the collegiate and little league levels, pitchers have become so efficient at their sport that they have developed different pitching techniques to alter the trajectory of the baseball.


At the base of these various techniques is the curveball. By altering one's grip, the baseball leaves the pitchers hand spinning in the direction of the pitchers choosing. The different grips the pitcher utalizes all offer different types of spins that the ball will move during flight. These various pitches have been named over the years, often according to the type of trajectory the ball will follow.

This link offers a few examples of the various types of pitches.
http://www.thecompletepitcher.com/different_baseball_pitches.htm


So, why does putting a spin on the baseball change the path it will take from the pitcher to the catcher? Interestingly enough, it manipulates the same laws of physics that an airplane does to gain flight. The airplanes wings are created so that the air on top of the wing has to move a greater distance in the same amount of time as the air on the bottom of the wing. This creates lower air pressure on the top of the wing, giving the plane it's lift.

Now let's inspect the trajectory of a curveball. When it leaves the pitchers hands, it is given a spin. Imagine that the ball is traveling from the right to the left. If you don't understand, then perhaps this awesome little text/image/thing will help.

Catcher <-----Ball----- Pitcher

Because of the spin given by the pitcher, the ball travels with a clockwise rotation the whole time it is in flight.

-------->

.........

.. ..
.. Poorly ..

.. Drawn ..

.. Baseball ..

.. ..

.........

<--------

This rotation, in combination the trajectory of the ball from the pitcher to the catcher, makes it so that the air on the bottom of the ball has to move faster than the air on the top. This means the ball will curve downwards as it travels.

This curve can be altered based on the positioning of the pitcher's grip.

Can you think of any other objects who's path through the air are altered because of its spin or rotation?

YOUR slinky drop videos!

Enjoy!
http://www.youtube.com/watch?v=brCeXn9tL6k
http://www.youtube.com/watch?v=V1rfJrXd03c&feature=channel_video_title

So... what did you learn from this demo?

Results of the 21Sept Brain Dump!

Here are your responses from today's question: "What's the most important thing you've learned thus far in this course?" Enjoy!

Preflight #6 responses

I’ve finished reading your great questions on Preflight #6. I apologize it took me so long to process them, but I think you’ll find the discussion worth the wait! Below are anonymous responses from students, each of which is followed by my commentary.

“I keep getting confused on how the powers like feet/second squared eliminates”

That’s a great topic! The goal is to keep track of what is in the numerator and what is in the denominator. For example, when we calculate velocity as distance / time, we have meters in the numerator and seconds in the denominator. Thus, the units come out to m/s. If we take a velocity and multiply it by a time, we’ll have units of (m/s) * s. The first “s” is in the denominator. The second “s” is in the numerator. If you were rearrange it, you’d have (m*s) / s. Rearrange it a little more, and you’d have m * (s/s), and s/s = 1, so you’re left with meters.

Another way of thinking of it is in terms of negative exponents. Remember that dividing by a quantity is the same thing as multiplying by that quantity raised to the negative one power. So, our first example of calculating velocity as distance / time is equivalent to distance * (time^-1). Thinking about the units, we have m * (s^-1), which is the same thing as m/s. Our second example of calculating distance as velocity * time then has units of m * (s^-1) * s. You can think of the “s” as s¹, so that we have m * s^{-1 + 1} = m * s⁰ = m * 1 = m.

The negative exponent method also comes in handy when you think about the units for acceleration. Acceleration is defined as change in velocity divided by the change in time, which would have units of (m * s^-1) / s, which, again, you can think of as (m * s^-1) * (s^-1). The units thus change into m * s^{-1 + -1} = m * s^-2 which is the same thing as m / s².

Ultimately, this is a skill that requires practice, so keep track of your units on every calculation you make (no matter how mundane), and you’ll have it down in no time!

“I only have a little bit of issues when I use Cos, Sin, and Tan to solve for problems.”

I think the most important thing to remember is the flow of information in the trig functions. The trig functions (sin, cos, tan) take in an angle and produce a number. That number is the ratio associated with that trig function (opp/hyp, adj/hyp, and opp/adj, respectively). Just remember that “sin(whatever)”, “cos(whatever)” and “tan(whatever)” are numbers, pure and simple. They’re just wearing a costume until you plug it into your calculator.

The inverse trig functions, on the other hand, take in a number and produce an angle. That number, again, is the ratio associated with that trig function.

“The only thing that I have trouble when it comes to any math is knowing when to use a formula. We learn a lot of formulas, and I can do them pretty good when were on the topic, but when we go back to it a while after i have trouble picking out which formula the question is asking for.”

Choosing an equation is a very important skill! I think that if you practice good bookkeeping at the beginning of the problem (writing down what you know and what you’re looking for), it can help the selection process.

I do notice you highlight that you have trouble remembering after “a while.” Might I suggest trying out problems immediately (or at least within a few hours) after class?

“It is taking multiple attempts for me to get [the problems] correct.”

That’s actually a very typical experience! Succeeding at physics requires practice—lots of it—which is why I think the Practice Flights are so valuable. Be sure to leave yourself enough time to try them again and again until you get the correct answer! (You might even need to plan to spend a few different sessions trying out the problems. For example, half an hour on Friday, Saturday, and Sunday each would be more valuable than 1.5 hours only on Sunday.)

Physics in Roller Coasters

So we all know what a roller coaster is and, unless you have been living under a rock your whole life, you have probably had the pleasure of riding one. In fact, roller coasters have become so common in the entertainment industry that we rarely consider the forces being manipulated "in the service of a great ride".

The entire concept behind a roller coaster is that it utilizes gravity to make massive amounts of potential energy before releasing them in the form of kinetic energy. In order to create the first and greatest reservoir of potential energy, the cars make their way up the first hill. This ascent is usually initialized with the chain lift, which acts as a conveyor belt to bring the coaster cars to the peak of the hill. At the top, the car's potential energy is as high as it will be for the rest of the ride.

After the chain lift disengages, gravity takes over and acts as the source of energy acting upon the coaster. As the cars descend, their potential energy is lost and in return they gain kinetic energy. Upon reaching the bottom of the hill, almost all of the potential energy is gone. However, on it's way over the next hill, the coaster loses some of its kinetic energy and gains some of its previous potential energy. This continues till it reaches the crest of the second hill

at-which-point the process begins again.

This link has an interactive image/video thing that can help to better explain kinetic and potential energy: http://science.howstuffworks.com/engineering/structural/roller-coaster3.htm

Because an object in motion tends to stay in motion (Newton's first law of motion), the coaster will maintain a forward velocity even as it climbs up the hills, working against gravity. This makes it possible for there to be any variation in the slope of the track, such as the swerves, hills, and loops.

Here is a cool picture that displays forces that I'm not going to talk about.

Due to friction between the train and the track, as well as the train and the air, the coaster continually loses kinetic and potential energy. For this reason, the hills decrease in size as the cars make their way through the ride. Eventually, the ride slows down to the point that it is unable to move forward any longer. By now the tracks have lead back to the beginning of the ride and the brakes are activated.

Sources:

• science.howstuffworks.com, "How Roller Coasters Work", Tom Harris
• Common sense and experience

Mapping g on the moon

http://www.npr.org/2011/09/10/140361610/nasa-launches-probes-to-study-moon describes a recently launched unmanned NASA mission to the moon to map out the moon's gravitational field. What is the gravitational field? It's quite simply the acceleration due to gravity ("g" as we've been calling it in class) as a function of position around the moon!

On the surface of the earth, g is a pretty consistent 9.8 m/s^2, but it does vary depending on your position on the planet, since Earth is not a perfect sphere. And once you start to get out into space, g begins to diminish drastically, dropping off like 1/r^2, where r is the distance between you and the center of the earth!

The moon's acceleration due to gravity behaves much the same way. On the surface of the moon (at least the parts we've been to!), it's about 1/6 of our g on earth (so about 1.7 m/s^2, give or take), and also drops off like 1/r^2 (where r is the distance between you and the center of the moon) as you leave the surface.

These probes will measure these variations in the moon's g as they orbit on opposite sides of the moon! By the way, the GRACE mission (http://www.csr.utexas.edu/grace/) did the same thing on earth! Here's a map of the results, depicting the difference between the local g and the average g: http://www.csr.utexas.edu/grace/gallery/gravity/03_07_GRACE.html, where the red regions represent a higher value of g and the blue regions represent a lower value of g (measured in units of "milligals," which are named after Galileo; 1 gal = 1 cm/s^2).

The Spruce Goose?

In 1942 the United States Government contacted Henry Kaiser a shipbuilder, to build a new airplane to carry troops across the Atlantic Ocean. When faced with this challenge Kaiser contacted famous plane designer Howard Hughes to help build this creation. Throughout the project the government kept their support but poked fun at his project. At one point the Senate even called this plane the "flying lumberyard" showing how immense this project was.

This plane was designed to be 400,000 lbs with a 320 foot wing span. THAT IS AS BIG AS A FOOT FIELD!!!! So you might wonder how this plane even would take off. It used eight P&W 4360 which are the same engines that are on the B-50's. However slapping eight huge engines on a pile of wood doesn't do much.

However, why did they call it the "Spruce Goose"? Most people who do not know about the plane think that it was made out of spruce. One of the biggest surprises that people might find out is that most of the plane is made out of birch not spruce. One reason the builders could have decided to use birch is because it is more dense and adds more structural integrity to the plane. Compared to spruce which is a little but of a softer wood.

My question for everybody is with all of the modern technology what is one thing that the designers of this plane could have done differently to make it fly more effectively?

Week 2 In-Class Problem - Monorail!

(Here's why I add the exclamation mark:

)

Below are pictures of your solutions to the monorail problem(s) from today!

What questions do you have for each other about your solutions? Fellow blog authors: What questions do you have for the aviation students about their solutions?

The GAU-8 Avenger Gatling Gun

In 1861 Richard J. Gatling designed and developed the Gatling gun, a rapid and continuous firing weapon to be used by the Union forces in the American Civil War. Through years of research and upgrades, the United States Military slowly redesigned this deadly machine until it could be most effectively used in modern day battlefields. In 1977, the newest form of the Gatling gun was introduced into the service of the U.S. Military. This weapon is now commonly known as the GAU-8 Avenger, a weapon so powerful and destructive that it forced the military to develop plans for a completely new aircraft, the A-10 Warthog, simply to be able to transport it efficiently.

This weapon, weighing just under 2 tons, measures roughly 19 feet and 5.5 inches (5.931 m) from the muzzle to the farthest point of the ammunition system. All together, the gun in its entirety takes up a little over a 3^rd of the plane, which reaches 53 feet and 4 inches (16.16 m) from nose to tail. Because of its impressive size, the nose wheel of the A-10 Warthog must be offset to make room for the massive gun along the central axis. In essence, although the A-10 does carry various forms of explosives in its arsenal, the GAU-8 Avenger dominates the aircraft.

In order to avoid overheating, the GAU-8 utilizes 7 barrels, each measuring over 5 meters long. When active, the gun spins at such a rapid rate that it has a potential of firing 4200 rounds per minute. Each of these 30mm rounds, along with the plastic and metal casing surrounding them, are 29 cm long and weigh more than .5 kg. Because of the weapon’s impressive length, along with internal rifling grooves, each round can travel up to 6 km, accurately striking up to 80% of its rounds within 10 meters of its target.

The GAU-8 fires two different types of ammunition, the PGU-14/B Armor Piercing Incendiary and the PGU-13/B High Explosive Incendiary, each round reaching a velocity of 3,500 f/s (roughly 1,070 m/s). Because of the high mass of the ammunition and the explosive nature of each round, the weapon is fully capable of penetrating 38mm of armor at a distance of 1000 meters. This is saying that each individual round has the capacity to penetrate any vehicle supporting 1.5 inches of armor before exploding, very likely destroying vital machinery and killing anybody unfortunate enough to be nearby.

Here’s a video link for all you lazy people out there who just skimmed the information above… http://youtu.be/1Oc-xbpy-OI

To summarize, this gun was created with the single minded goal of messing tanks up. And the best part of all is that this was all made possible by mankind’s knowledge of applied physics. And so I ask you, what other forms of aircraft technology and accessories can you think of whose creation can be credited to modern day physics? Can you think of any improvements to technology that will become available to us in the future? If so, explain.

Introduction

Hello Everyone,

My name is VonHayes Switzer and I am a sophomore Engineering Physics major. After my three years at Jacksonville University I plan to attend the University of Florida to earn my second bachelors degree in either Nuclear or Aerospace Engineering. When I graduate from there I plan on entering the Navy. My service selection would be pilot as most of you are, however, if I do not get that I will become a nuclear engineer.

Currently at JU I am involved in many different ways. I am an active brother in the Sigma Chi Fraternity, having been initiated last fall semester. I am also a Midshipmen in the NROTC program here on campus. Lastly I am a lifeguard at the Wurn pool working five days a week.

The question I would like to propose to you is if there was one plane, past, present or that you have heard is coming in the future, that you could fly what would it be and why?

My First Post

Well, it looks like I'm going to be your blogger for the semester. My name is Jared. I'm from Tampa, Fl, and I'm a 20 year old sophomore majoring in Engineering Physics. I'm a member of the JU Honors Society and I've been a part of JU's Crew program since my first semester.

Hobbies... Let's see. I like the beach and surfing. Also hanging out with friends. I'm starting a 10 gallon nano coral reef tank this semester, so if any of you are interested in that sort of thing then hit me up. I could use advice.

My room number is Oak 256. See me if you want or need anything. That's pretty much it...

Introduce yourself!

For your first blog assignment, post a comment in response to this article to introduce yourself. Tell us...

1. What your previous experience with physics is---even if it's simply, "I watched an episode of Mr. Wizard's World Bill Nye the Science Guy when I was a kid."
2. One question you'd like for a physics or engineering major to answer on this blog.
3. What you'd like to get out of reading and conversing on this blog.

Be sure to "sign" your post so that I can tell who you are. For example...

W. Brian Lane
wlane@ju.edu

A first post! More to come...

This blog will feature articles to supplement our discussions in PHYS 125 Aviation Physics in Fall 2011.

--Brian Lane