Jump to content

ThePeculiarParticle

Members
  • Content Count

    58
  • Joined

  • Last visited

  • Days Won

    3

Blog Entries posted by ThePeculiarParticle

  1. ThePeculiarParticle
    So, we always talk about the coefficient of friction in dynamics, but we don’t talk about what causes it. The truth is there are multiple factors. The one most people think of is based upon how rough a surface is.  Coarse grit sandpaper requires more force, and takes more material off an object, than fine grit. The same idea applies to smooth objects on a much smaller scale. Even something as smooth as the surface of a polished table, on a much smaller scale, has ridges and valleys. These imperfections are known as asperities (such an odd vocabulary word) and look similar to this.

    The top shows asperities between two objects before a load (force) is applied and the bottom shows after.
     
    These ridges and valleys are shaped in a way so that they oppose the movement in the direction the force is being applied. This seems pretty intuitive, but then there are instances of smooth surfaces sticking together, such as gauge blocks or wafers.
     
    I remember hearing about how gauge blocks could be “stuck” together and measured for more specific tolerances, but never understood why. Well the answer is a result of how they are made. Both gauge blocks and silicon wafers are polished very accurately for their uses, resulting in an extremely flat surface. The result is that the asperities are very limited leaving the contact between the two materials at a maximum.
    Van der Waals forces then take into effect if limited material or residue is on either surface. To sum up the effect, atoms have electron clouds, and while we ideally picture them as uniform, they naturally are not.  One side will have a slightly greater negative charge and the other will have a slightly greater positive. The surrounding atoms, will align themselves negative to positive resulting in a “sticky” force between them also known as London dispersion force.  It is also important to mention each individual electron cloud’s orientation is momentary, but across all atoms there are enough places where it occurs for the resulting force to be noticeable on a macro scale.

    This animation shows Van der Waals force in action.
     
    So, while the rougher a surface becomes the more friction it can have, the same can be said for how smooth a surface is.
    This is a very basic overview of what I learned, and I’m sure there is even more science behind these things the higher up you go, and I’ll see if I can update this, but consider this an overview.
     
    I also found a very interesting related video which will be linked bellow.
     
    As always thanks for reading – ThePeculiarParticle
     
     
  2. ThePeculiarParticle
    Yes, there has been some delay between posts, I apologize, but life is busy as usual. This week I wanted to cover the topic of pickups for string instruments. So I play electric bass and wondered the other day how different pickups get different tones and sounds out of them. You can have warm, mellow, fuzzy, even screechy tones all based on the different models.
     
    To answer this, we need to see how a pickup actually “picks up” the string vibrations, and it does so through Faraday’s Law. Faraday’s Law states that changing a magnetic field creates an electric current. Now the magnets mounted on the instrument are static, but the strings which vibrate are not. The vibration of a string disrupts the field and causes an electrical signal to be the output. The only time this is a problem is when a harmonic results in a node occurring over the pickup and  register as silent due to the string not oscillating at that point. This is where multiple pickups can be handy as they  can add a signal together if both register a frequency or one can register a frequency if the other has a node above it.
     

     Here is a picture of the system used to pick up an electrical signal.
     
    Many pickups are single coil as shown by a single row of magnets. While this may be a cheaper option, it is more prone to interference from surrounding equipment and signals. The most commonly used alternative is a Humbucker.
     
    Humbuckers work by using two coils housing magnets of opposite polarity. This creates signals out of phase in each coil. If these coils connect correctly it results in external electromagnetic  fields, such as from power lines, to be canceled out and the guitar signal is doubled.
     

     
    This diagram shows a simple circuit for a pickup. The resistor for tone effectively acts as a filter for higher level frequencies. Adjust the resistor and the frequencies which get cut also changes. The resistor bellow controls volume or amplitude of the signal before it travels through the cable to the larger amplifier. Every single one differs slightly so that the signals to every pickup on an instrument can combine and create a unique sound.
     
    Thanks for reading!
     
    -ThePeculiarParticle
     
  3. ThePeculiarParticle
    The holy grail of serves in volleyball is the jump spin serve. A serve going over a 2.43 m (7' 11 5/8”) can be understandably difficult for many, but higher level players are constantly trying to deliver more speed and directional movement to the ball in order to make it harder for the opposing team to return. The jump spin’s first benefit is, that by jumping, added height is given to the point at which the ball is contacted.  By doing this, the difference in height between the ball and the top of the net decreases, allowing for the serve to follow a flatter path than if hit while standing. This effectively reduces the travel time of the ball by making it a one sided curve rather than a parabola.
    The added benefits of a spin serve is that the ball can handle much higher speeds than a float (no spin) serve, and requires more effort to pass. The Magnus effect is to thank for this.
     What happens is that, as the volleyball player starts their approach, they throw the ball up giving it spin away from themselves. They then jump and contact the ball as it spins, giving it the topspin required to achieve the effect. To summarize the Magnus effect, when an object rotates, it has air which clings to its surface and follows its rotation. This layer then collides with oncoming air, which hits the ball as it travels in the horizontal plane. The deceleration caused by this collision creates, in this case, a high pressure pocket of air above the ball and a low pocket of pressure below. The object then is acted upon by a lift force, in this case known as a Magnus force, due to the object being compelled to travel in the direction away from the high pressure pocket of air to the low pressure pocket.
     
     
    This illustration shows the top spin given to the ball, the low air pressure below the ball, and high pressure above the ball, and the resulting force.
     
    Effectively, the velocity can be increased since the greater the spin the faster the ball will drop.  When passing the ball, players must also be cautious.  If it hits their arms without providing some sort of counter spin, like pulling their arms in as it hits, then the ball will keep its spin from friction, and go off the passers arms behind them.
    The jump spin serve is a mean serve on many levels, and those, like TheNightKing (shout out), who can do it fairly consistently, are valuable at varsity level and nearly necessary to play in higher levels. Just make sure you put spin on the ball before you contact it as hard as possible, otherwise it will fly into the next county instead of hitting the court.
    Here are some other videos on the Magnus effect:
     Jump serve:
    Magnus effect explained and its applications:
     
    Added Note:
    Here is that KFC I was talking about...

  4. ThePeculiarParticle
    1.
    A.) There are several misconceptions about studying that can hurt you in the long run which include:
    Learning is fast
    Knowledge is composed of isolated facts
    Being good is a born talent
    I can multitask
    B.) The misconception which resonates with me the most is that “knowledge is composed of isolated facts”. It seems that many teachers, when focusing on studying, believe that vocabulary is the best way to digest information. Personally, I have always had trouble studying in this way. Now, knowing that mapping out information is the way to go, I feel like my study habits are already better prepared than I once thought for this year.
    C.) Many students need to develop a new sense of metacognition once they arrive at college. This is the perceived sense of awareness on a certain topic. Many students when taking their first exam, go in overconfident not realizing that they have not prepared well enough to pass the exam. Only through good study skills, along with trial and error can a person develop an accurate sense of metacognition.
     
    2.
    A.) Many students have misconceptions on what factor plays the biggest role in successful learning. The truth is that what you think about when studying is most important. The less distractions a person has, the more focused a studying experience they can have by using methods of deep processing.
    B.) Deep processing is going beyond simply trying to store the information given to you, as it is unlikely your brain will retain it. It is expected that deeper connections are made with the material which include: creating an emotional connection, organizing and visualizing how information goes together, or asking yourself questions how a teacher would. Deep processing is much more about comprehending the whole subject matter rather than being able to pull out tiny bits of information. This will be much more valuable on a test, and even in the long run, when future topics build off the same information.
    C.)
    1.Minimizing Distractions - With more distractions more time is spent not studying and not absorbing the information.
    2.)Developing accurate metacognition- It is important, as a student, to know one's limits and when they can push themselves further in order show they have mastered the work.
    3.)Deep, appropriate processing of critical concepts - Using deep thought and connecting all information can be quite difficult but it is one of the only ways to learn a topic thoroughly.
    4. Practicing retrieval and application - This acts as a simulated testing situation forpeople as they need to be able to recite and connect information in a coherent and quick manner.

     
    3.
    A.) Optimising learning is the number one way to prepare yourself for any exam or future instances where you need to need to look back upon learned information. The first strategy is elaboration, such as, how do concepts relate to other concepts. An example would be relating derivatives to finding instantaneous forms of motion on a graph, as it spans the gap between physics and calculus and provides real world applications. The next aspect is distinctiveness. For this unit alone, recognizing that average velocity is different than instantaneous velocity can mean the difference of understanding a problem or getting the incorrect answer. Another aspect is making information personal. I believe many of the problems in class already achieve this by focusing on topics which center around comedic scenarios or people’s interests. The blog posts will be our personal time to relate physics to what we are passionate about. The fourth aspect is practicing appropriate retrieval and application. I feel the best way to do this is by helping others as you need to know the information to teach it and it truly makes a person verbalize the varying concepts in their head. The second to last aspect is Automaticity, which usually lends itself to practicing an excessive amount of problems on the subject. If you can look at a problem, and have done so many practice problems where you know how to start it and then work through it without truly struggling, you have achieved this level of mastery. The final aspect is overlearning. To do this one must study the information to the point it can be recalled quickly and easily. I believe the best way to do this, for me, is to sit down with someone else and try having a conversation/interview about the topic to the point where it seems natural. At this point, a person should be able to tackle the comprehensive questions which are given to them.
     
    4.
    A.)  What is metacognition? Metacognition is the ability to tell how well you have mastered a material.
    In the video, how did the teacher test for metacognition? Prof. Chew asks his students what they predict they shall score on their first test. He then compares it to their actual scores. The estimated percent is a x coordinate with the actual being the y coordinate. A line with a slope of 1 was created and anyone who scored lower than the line shows a sense of overconfidence and lack of metacognition.
    How does poor metacognition hurt academic success? Poor metacognition can fool a person into feeling they are ready for a test when they are not causing them to fail.
    Why would metacognition that was good in high school be bad in college? In high school the curriculum focuses more on shallow learning and memorizing small facts while college focuses on deep learning over prolonged periods of time.  
    What are the critical differences between deep and shallow processing? Deep processing centers much more around why and how things work and connect. Shallow processing is more simply reciting information.
    Name a task you already do where you automatically use deep processing.  When I play volleyball I use deep processing especially when analyzing a hitter that I am supposed to be blocking. How is he an asset to the team? What are his strengths? What are his weaknesses? How does he plan to perform this play and how can I react to his move in the best possible way? All of these questions bounce around in nearly an instant between play.
     
    B.) Just as in a real world lecture, writing down everything the video tells you is a bad idea and will leave the important notes lost in a sea of less usefull information. Notes should paraphrase and summarize in order to be a useful tool. Video lectures are nice as they are already recorded so any information missed can be gone back to if not fully understood or needed to be explored further. While it is much harder to miss a video lecture than an in class lecture, taking the notes and copying them from someone else is a horrible idea, as you are using second hand information as your first hand. The best source to get it from is the lecture itself and, most importantly, a person can have faith that they are not writing down any misinformation.The tip for organizing notes is necessary for both, as notes are not a one time source of information. When a person inevitably looks back on them, they want to be able to quickly access the topic and information they are looking for amidst all the others.
    C.) A study group is very valuable in this class. I already have a small one forming and, so far, it has worked out tremendously with each member contributing to different problems which the others were stuck on. The best method of learning is through teaching others and, when that can happen equally amongst people in a group setting, then it is a beneficial relationship for all parties involved.
     
    5.
    A.)There are appropriate ways to handle an exam which can aid you in future exams, but there are other habits which shall certainly hurt you. Some behaviors to avoid while preparing are: studying the same as you did for prior exams, waiting to ask for help, skipping class to catch up on others, cramming, falling behind, and skipping assignments. The main things to avoid directly after you do poorly on an exam are panicking and going into denial. A person should look at this moment and take it as the learning experience that it is and take the steps necessary to do better in the future.
    B.) If you do end up failing, there are some strategies which help greatly. The strategies recommended are: to honestly examine how you prepared, review the exam, compare it with your notes, talk with your professor, examine your study habits and develop a plan for your future.
    C.) A few helpful strategies can guarantee a good grade for the future. These steps include: committing an appropriate amount of time and effort to your work, minimizing any distractions you experience, attending class, setting realistic study goals, not letting work slide, as it will only build up, and not giving away easy points (not following simple instructions). With these tips grades can improve along with your outlook on failure not being an obstacle but a learning point.  
  5. ThePeculiarParticle
    I enjoy being a student at IHS and being able to take a lot of classes in the STEM areas. I like to problem solve and create solutions, following them through from design phase to hands on building. Encountering a challenge is rewarding to me, and I believe that is the main reason I picked this class. I also have always been fascinated by concept of putting numbers to nature since I was a kid. To me, physics is like taking a big mess and then breaking it up piece by piece to understand it and bring some order to natural behaviors. That is not to say everything can be, with 100% certainty, explained in the present. After all, there is still theoretical physics and these points of points of possibility can be just as, if not more, exciting.
    What I am mainly looking forward to about the class is the university feel of it. It is easily one of the most independent classes in the school and will be a good course in preparation for next year. The thing I look the least forward to is the workload, but it seems, with some time management and determination, the workload will be fine. I look forward to reading all the other posts on here and the topics you guys choose.
    -ThePeculiarParticle
  6. ThePeculiarParticle
    Physics is all around us, and sometimes it is so visually awesome that it can make for great album covers.

    Pink Floyd: The Dark Side of the Moon
     
    One of the highest selling albums of all time, and having one of the most identifiable covers of all time, Pink Floyd should rightfully start up this list.
    The phenomenon shown is called dispersion of light. This occurs when white light hits an optically permeable surface. In this case, white light is hitting a prism. As white light passes through the prism, all the different components of white light separate by wavelength. This occurs due to each wavelength having a different angle of deviation. Shorter wavelengths, such as violet, have greater angles of refraction than longer wavelength colors, such as red. The result is a splay of colors each aligned in a rainbow to their corresponding wavelengths.

     
     


    Joy Division: Unknown Pleasures
     
    Another cover which can be easily recognized, or at least will be noticed, is Joy Division’s debut album. What you are actually seeing is a visualization of radio waves from a pulsar, in fact the first pulsar ever discovered. A radio pulsar is a neutron star which is spinning at incredibly high speeds. So this star, with a density ten trillion times denser than lead, is also generating a strong magnetic field from moving electrons. Due to this spin, electrical charges, and magnetic field, a radio signal was received at 1.337 second intervals. The picture above depicts eighty successive periods stacked on top of one another, and was taken straight from The Cambridge Encyclopaedia of Astronomy published in 1977. Despite being in earlier publications, the true creator of the design is not know, but if one thing is for sure, the image can still be found everywhere and this usage in 1979 was only the beginning of its use in pop culture.



    The Strokes: Is This It
     
    The cover to The Strokes Is This It was chosen for release of the 2001 album due to its beautiful psychedelic appearance. But what is it? Well, it is a picture taken from inside a bubble chamber. A bubble chamber is used to study electrically charged particles. How it works is that large bubble chambers are filled with incredibly hot liquid hydrogen. As the particles enter the chamber, a piston opens decreasing the pressure in the chamber. Charge particles created an ionized track which vaporizes the hydrogen creating visible bubble trails. Since the hydrogen is transparent, pictures can be taken in all three dimensions, mapping out the movements of the particles. So why is a different bubble chamber photo my profile picture?
    Well it has nothing to do with The Strokes. It's just a beautiful image, and that's what made most of these artists choose their own covers. Nature is beautiful in many ways, and being able to explain it with physics makes it just that much more enjoyable.
     
    As always thanks for reading! - ThePeculiarParticle

Terms of Use

The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.

Copyright Notice

APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to info@aplusphysics.com. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.

×
×
  • Create New...