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goalkeeper0

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Blog Entries posted by goalkeeper0

  1. goalkeeper0

    Liquid Magnets?

    By goalkeeper0,

    Most people think of magnets as a solids. But, think again. A "liquid" form of magnet exists.

    Ferrofluids contain magnetic particles in a liquid carrier, and act like a "liquid magnet." Ferrofluids do not clump together to form solids because of a surfactant, which coats the magnetic particles. The surfactant overcomes the magnetic forces between the particles and keeps the solution a liquid. A ferrofluid is primarily made of a liquid carrier, and contains relatively small amounts of magnetic particles and surfactant. Depending on the ratio of liquid carrier: magnetic particles: surfactant, ferrofluids range in viscosity and magnetization.

    How do ferrofluids work?
    When a magnetic field is applied to a ferrofluid the magnetic particles quickly align themselves along the magnetic field lines. Ferrofluids can be precisely positioned and manipulated by an external magnetic field. When a magnetic field is not present, the particles of the fluid are randomly distributed in no particular arrangement.

    How are ferrofluids used?
    Ferrofluids are applied in a variety of ways. Some ferrofluids are used as adhesives, particularly in the speaker industry. In the computer world, ferrofluids act as lubricants. For machine tools, ferrofluids come in the form of a liquid spray. Ferrofluids can also plate and protectively seal materials from the atmosphere and harmful contaminants. When correctly used, a ferrofluid can improve a product's performance.
    [ATTACH=CONFIG]620[/ATTACH] [ATTACH=CONFIG]621[/ATTACH]
  2. goalkeeper0

    Weight loss solution

    By goalkeeper0,

    Around the holidays, people typically gain weight as cookies, candy canes, and other treats are around every corner. But, this Christmas, you can lose weight! Without a diet, and without exercise, there is one answer to the essential question: "How can I lose weight?" Simple. Go to the moon.

    Here is the calculation to prove this solution really works!

    1) Find g:
    g=[G(mass of moon)]/[(radius of moon)^2]
    g=[6.67x10^(-11) x 7.35x10^22]/[(1737000 m)^2]
    g=1.62 m/s^2

    2) Convert your weight from lbs to kg
    130lbs=59 kg

    3) Weight (N)=mg
    Weight = 59 kg (1.62 m/s^2)
    Weight on the moon= 95.58 N

    So, what do these results mean?
    Your weight loss can be measured in Newtons as you went from about 579N to about 96N. Or, in lbs, you went from 130lbs to about 22lbs!
    On the moon, you weigh approximately 17% of your weight on the earth.
  3. goalkeeper0

    Winter Driving

    By goalkeeper0,

    Don't let four-wheel drive fool you, because any car can spin out on icy, snowy turns. In wintry weather, drivers must slow down or shovel their way out of a snow bank. Why must drivers slow down? The coefficient of friction between rubber tires and snow is much less than the coefficient of friction between rubber tires and dry pavement.
    The coefficient of friction between pavement and tires is about 1.00; whereas, the coefficient of friction between snow and tires is about 0.30.
    So, how much must a person really slow down while driving around a banked turn?

    vmax=(urg)1/2 r= radius of turn, u= coefficient of friction, g=9.81m/s2

    vmaxpavement=(1.00 x 10.0m x 9.81m/s2)1/2= 9.9m/s=22.1mph

    vmaxsnow=(0.30 x 10.0m x 9.81m/s2)1/2= 5.4m/s=12.1mph

    Physics proves you must slow down!
  4. goalkeeper0
    Opening a fresh jar of pickles can be challenging. If you are somebody who struggles opening jars, don't be discouraged, physics can help. If you run the jar under hot water, the lid will become easier to turn. But, why? Metal has a higher coefficient of expansion than glass does. So, as the jar stays under the hot water, the metal expands a tiny bit, and the glass stays the same. There is no longer a need to workout, just run your tricky jars under the faucet, wait a minute, and let physics take care of your problems.
  5. goalkeeper0

    Living on Mars

    By goalkeeper0,

    Population concerns on Earth are leading scientists to inquire whether colonizing Mars is possible. As of now, over 78,000 people have applied to leave Earth forever and live on Mars. Mars One, a nonprofit organization, is sponsoring the colonization with a take-off date sometime in 2023. Out of the applicant pool, four will be chosen to send first to Mars. The first four will lay the groundwork for a permanent colony. Two years after the first four land, Mars One would send up more people to the colony. With the application process underway, it seems as though scientists have discovered ways for humans to survive on Mars indefinitely. However, this is not the case. Many, many concerns exist such as how will the colonists feed themselves? Will crops which grow on the Earth also grow on Mars?

    The first settlers of Mars will most likely be farmers. Yes, they will be astronauts; but, if survival is of any importance to them, they will learn to farm in order to eat. Research which has been conducted supports the idea that growing crops is possible in microgravity. However, those working for NASA do not know to what extent the gravity of Mars will effect crop growth. Also, Mars' surface only receives about half of the sunlight that the Earth's surface receives. Will plants be able to grow with limited sunlight? On top of the already limited sunlight, pressurized greenhouses would be necessary to grow crops. The greenhouses would block out more light. So, additional light would be necessary from other sources than the sun. What would power additional light sources? How would that power be generated and sustained?

    Radiation would also be a problem faced by those on Mars. Mars does not have as strong of an atmosphere as the Earth. More radiation reaches the surface of Mars than the surface of the Earth. Inhabitants would need a way to reflect the radiation or shield themselves from the rays.

    To live on Mars, man must master the art of agriculture in microgravity. Feeding the inhabitants of Mars is one among many more necessary tasks of survival. As of now, research is still being conducted. The 78,000 who have already showed interest in living on Mars are a bit stupid or extremely bold. With current technology man would not survive on Mars. I do not doubt though that technology will develop in the near future for man to successfully live on Mars.
  6. goalkeeper0
    A couple games ago, my soccer team had ample opportunities to score against Gates Chili. We managed to sky the ball over the net from the six yard line, in the first five minutes of the game. After thinking about how hard it is to miss the goal from this distance, I thought I would compute the angle, theta, needed to clear the crossbar (8ft off the ground) from the 6-yard line.
    Given: *average velocity of shot ~45ft/s
    (this value varies between male/female, and level of play)
    *delta x=18ft
    *delta y=8ft *g=-9.81 m/s2=-32.12 ft/s2


    Find time in terms of theta: delta x= (velocity in x direction)(time)
    time=(18/(45cos(theta))) s

    Find Minimum Theta: delta y=(V-initial in y direction)(time)+(0.5)(g)(time)2
    8=18tan(theta) - (2.57/cos2(theta))
    Solve for theta and get.....
    theta must be greater than 32.9 degrees to miss the goal.

    Conclusion: Given that the ball is kicked around 45 ft/s, 32.9o< theta <90o would cause the ball to go over the crossbar!
  7. goalkeeper0
    After laying low for awhile, cross products have suddenly became very important in our current independent unit on Magnetism. For those who may have forgotten how to find a cross product, here are some reminders.

    1. Cross products are needed when the multiplication of vectors is involved in the problem
    2. To find cross product of a x b [where a is (ax,ay,az) and b is (bx,by,bz)]
    cx=(aybz-azby)i
    cy=(azbx-axbz)j
    cz=(axby-aybx)k
    3. The cross product is then written:
    a x b = (cx,cy,cz)
    [ATTACH=CONFIG]625[/ATTACH]
  8. goalkeeper0
    Circuits with resistors:
    In series:
    Req=R1+R2+R3+R4+...
    I=I1=I2=I3=I4=...
    V=IR1+IR2+IR3+IR4+...

    In parallel:
    1/Req=1/R1+1/R2+1/R3+1/R4+...
    I=I1+I2+I3+I4...
    V=V1=V2=V3=V4=...
    Note: Replacing resistors in parallel with one resistor of equivalent total resistance is very useful when analyzing circuits

    Circuits with capacitors:
    In series:
    1/Ceq=1/C1+1/C2+1/C3+1/C4+...
    Q=Q1=Q2=Q3=Q4=... (Conservation of charge)
    V=V1+V2+V3+V4+...

    In parallel:
    Ceq=C1+C2+C3+C4+...
    Q=Q1+Q2+Q3+Q4... (Conservation of energy)
    V=V1=V2=V3=V4=...
    After a long time, a capacitor acts like an open spot in the circuit; current through the section of the circuit with the capacitor= 0 A

    RC Circuits:
    Time constant=RC, or Greek letter tau
    I=-dQ/dt
    When a resistor and capacitor are in parallel, voltage drop across resistor=voltage drop across capacitor.
    When a resistor and capacitor are in series, current is the same through the resistor as through the capacitor.

    Charging RC Circuit: Current decreases over time. Charge on capacitor and potential drop across capacitor increase over time.
    *In the long run,VC=VT (V-terminal=V-capacitor)
    *I=(VT/R)e-t/RC
    *Q=Qf(1-e-t/RC)
    *Qf=CVT

    Discharging a capacitor: Current flows from the positive plate of capacitor to the negative plate and through the resistor. Current, charge, and voltage decrease over time.
    *I=I0e-t/RC
    *Q=Q0e-t/RC
    *I0=V0/R=Q0/(RC)
  9. goalkeeper0

    Free Falling

    By goalkeeper0,

    If you ever find yourself in Las Vegas with nothing to do, $100 to burn, and gambling isn't your forte, head over to the Stratosphere Casino/tower.
    At the Stratosphere, you can experience the thrill of free fall as you descend 108 floors to the ground. After taking the elevator to the top of the building, you receive a brief "safety lesson." Then you saddle into the harness, say a prayer, and jump! (Ok, this isn't true free fall. A long cord is attached to your back which slows you down for the last 20 ft of the drop.)

    But, for physics sake, let's say that a person jumping off the Stratosphere was in perfect free fall. What would the maximum speed of the brave yet stupid jumper be?

    Vmax occurs as the person hits the ground
    h= height of the building, ~260 meters
    g= acceleration due to gravity, 9.8 m/s2
    Conservation of energy: mgh=(1/2)mvf2
    vf=(2gh)1/2
    vf= 71.4 m/s which is about 159.7mph...This is the speed the jumper would hit the ground at if the cord snapped..ouch

    The Stratosphere SkyJump claims that its jumpers reach speeds up to 40mph which is much different than 159.7mph! The attached cord and drag force work together to slow the person down during the jump--it's a good thing!
    [ATTACH=CONFIG]633[/ATTACH]
  10. goalkeeper0
    What are oscillations equations without gravitation equations?

    Gravitation:
    T12/R13=T22/R23
    G= 6.67x10-11
    g=Gm/r2
    Fg= -Gm1m2/r2
    Potential Energy= -Gm1m2/r
    Vorbit= [Gm1/R]1/2
    Vescape= [2Gm1/R]1/2
    T=(2(pi)R)/v
    Total energy for a circular orbit= (-Gm1m2)/(2R)
    Total energy for elliptical orbit= (-Gm1m2)/(2a) ; a= major axis radius
    Velocity/Radius relationship for elliptical orbits: vprp=vara

    Overall, there aren't too many equations to remember for this topic. But, all of the equations are very similar. So, memorize!
  11. goalkeeper0

    Physics News Alert

    By goalkeeper0,

    This is my first blog post with nothing to do about soccer! Tonight, when my dad was reading the Democrat and Chronicle, and I was doing my Calculus homework, he read me a blurb about an American and French Physicist who just won a Nobel Prize in Physics. The paper didn't explain much of anything in terms of what these physicists did to merit the prestigious award. I think the brief description was because the physicists, Serge Haroche and David Wineland, studied quantum physics and applications between quantum physics and computers. I do not think many people would actually understand what these men did if the newspaper went into further depth into their research/studies. I tried to understand the breakthroughs these men made in the physics world. So, I looked them up online and found this website, http://www.pcmag.com/article2/0,2817,2410825,00.asp. I learned that they separately studied interactions between light and matter. In particular, Wineland's work made strides toward the first "quantum computer," which would run much faster than a normal, digital computer. Wineland and his research team also created a clock that is one hundred times more precise than the most precise clocks we use today for the standard of our measurement of time. Wow.
  12. goalkeeper0
    In college, I plan to major in biomedical engineering. Biomedical engineering combines biology, chemistry, physics, and math into one field of study. The field is very broad; so a biomedical engineer usually focuses on one specialization, some of which include medical imaging, biomechanics, bioinstrumentation, genomics, robotics, clinical engineering, tissue engineering... I am not sure which specialization I will follow yet; however, I think that tissue engineering is extremely fascinating. Tissue engineers are constantly finding new ways to grow skin, bones, cartilage, and even organs. The theory behind tissue engineering and regenerative medicine is that an organ made by a patient's own cells should be easily received by the patient's body. With typical transplants (transplanting an organ from human to human or animal to human), there is always risk of rejection. As strides are made in the field of tissue engineering, the results are promising. If tissue engineers can streamline the process of growing organs, people would not have to wait on transplant lists and pray for a suitable organ to turn up.

    The process of "growing" organs involves many steps. One of the first steps is called electrospinning. In this process, positively charged nanofibers are transferred from a syringe which is positively charged to a spinning cylinder which has a negatively charged plate behind it (physics ) . The nanofibers travel along the electric field lines, and accumulate evenly on the spinning cylinder. After enough fibers have accumulated, the engineer stops the machine. The deposited fiber is removed from the tube; and a thin sheet is end product. The engineer uses the thin polymer to construct a scaffold. Cells are placed on the scaffold which multiply, differentiate, etc. to form the intended organ. The scaffold provides a structure for the cells to form around. Once in the body, the organ slowly develops around the scaffold. Due to the composition of the scaffold, it slowly is absorbed by the body over time, leaving just the organ in place. Ta-daa! An organ has just been made!

    This is a glimpse at one step in the long process of creating an organ. Many chemical and biological steps come next, but this is physics so I will stop here.
    All in all, three cheers for E-fields which allow super thin nanofiber sheets to form!
  13. goalkeeper0

    Black Friday Tips

    By goalkeeper0,

    As Thanksgiving is just around the corner, retail stores are bombarding consumers with Black Friday ads. The ads show glittery, appealing products at low-prices. But, what the ads do not show--crowded parking lots, irritated customers, and stampedes-- you must watch out for. To minimize your risk of injury, here is some physics advice if you are one of the bold buyers who battles Black Friday crowds.

    1) Attempt to maximize your power (force dotted with velocity) beforehand. A balance of force and velocity is necessary. Do not bulk up, because your velocity will suffer, and you will be at the back of the crowd. However, if you are relatively mass-less, but fast, you will also be at the back of the crowd.

    2) Bring along a friend! With a friend to help carry your purchases, more work can be done. As work is force dotted with displacement, lifting heavy boxes, pushing televisions, etc. will be much easier with the help of an assistant.

    3) Avoid stores where a wide waiting area slims down to a narrow entry. Why? Conservation of flow rate. Flow rate= Area of space for people x velocity of the crowd. Therefore, when people head toward the doors, the velocity of the crowd must increase as the Area of the space decreases, to conserve flow rate. This means that as you approach the door of the store, the speed at which people are "flowing" increases. This is how many stampedes occur.

    All in all, if you do venture outside in the wee hours of the morning, fuel up! Eat healthy foods beforehand to give your body the necessary potential for success.:eagerness:
  14. goalkeeper0

    Oscillations Review

    By goalkeeper0,

    As we are in our second independent unit, I thought I little review picture couldn't hurt. Remember:
    1.) Max acceleration is achieved when the spring is at -amplitude or +amplitude.
    2.) Max velocity is achieved at equilibrium.

    And, along with this, we must know:
    KE= (1/2)kA2sin2(wt) w= angular frequency, k= spring constant, A= amplitude, t= time
    PE= (1/2)kA2cos2(wt)
    These equations are useful when finding the Potential or Kinetic Energy at time, t, in the oscillation.
  15. goalkeeper0
    So, this first blog entry is an introduction to me, goalkeeper0. As seen in my username, I obviously am a goalkeeper (for soccer)...I will soon post a blog entry about a recent soccer/physics encounter of mine. So, about me. I am interested in a combination of all three sciences, Biology, Chemistry, and Physics. Thus, in college, I hope to study biomedical engineering-- which brings together both engineering and medicine. Biomedical engineering appeals to me, because of its many different career paths, whether that be in imaging, regenerative medicine/tissue engineering, work with prostheses, etc. Originally, I was just going to take AP Chem this year, but I really wanted to take Physics C too. After reworking my schedule, I added Physics C, because I want a strong Physics background going into college. Plus, I like taking challenging courses. Last year, I enjoyed AP Physics B a lot more than I thought I would, and I look forward to learning Physics with Calculus. By the end of the year, I hope to be a confident physics student. I look forward to learning with you all (fellow Physics C students)! What am I most anxious about? Well, I really don't know yet. But, as soon as we get deeper into Physics C, I bet I will be anxious about pretty much everything...but I suppose that is normal.

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