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bdavis

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  1. bdavis

    "Tag"

    By bdavis,

    We just recently finished a game in calculus. We called the game “tag” but it really was a game of assassin where we could get people out by shooting them with water guns. We had to be very stealthy because no one was supposed to know about it. To keep up with the stealthy behavior, shooting long range squirt guns would have been really effective to get people out without them realizing what hit them. In the beginning of the year we conducted a lab with q-tips and plastic straws. That lab demonstrated the concept of velocity and the relationship between displacement and acceleration. If we had water guns that had a longer nozzle with triggering mechanisms that would apply a constant force on the water from the beginning to the end of the nozzle, then the water would be accelerated over a longer displacement. F=ma and the longer an object is accelerated, the greater its velocity. Water guns with longer nozzles would be able to shoot water out faster and over longer distances if shot with an angle of appropriate trajectory. If they weren’t that noticeable, then it could have worked to our advantage. The best assassins have a good understanding of basic physics.
  2. bdavis
    In light of the end of school, I want to review how my 4th quarter has been. My third quarter was slightly less than stellar taking into account my previous accomplishments and I feel like that was the “swift kick in the a**” that I needed to get right back on track. From then on in the 4th quarter, I turned things around, studied hard for my AP classes and did well on my exams. After that I focused on my other non- AP classes and increased my grades considerably. In physics, we started the Kerbal Space Program and that was a lot of fun but at the same time it was educational. We got to learn about the physics of flying a rocket and how to manage a business through our online write-ups. My partner Zach did most of the work because he thoroughly enjoyed it but I forced my way through in the end so I could get a taste of that experience. I will always regret doing these blogs late because that wasn’t fair to my family or my physics C teacher who was kind enough to accept them. Overall I feel like the 4th quarter went well but I still have some work to do before college.
  3. bdavis
    One of the simplest baseball drills that only requires one person, a glove, a ball and a wall exhibits one of the basic yet essential physics concepts: Newtons third law. Newton's third law states that if something applies a force on an object, that object will apply a force of equal magnitude in the opposite direction.

    So when training for baseball, someone can throw a baseball against a wall with a certain force and the ball will come off the wall with the initial magnitude it first hit the wall with, but in the opposite direction. Newton's third law didn't take into account friction so the ball will be subjected to air resistance and won't make it back to the person with the same velocity but for the instances it strikes the wall and comes off the wall, air resistance is negligible. Therefore, Newton's third law can be observed.

  4. bdavis

    Centrifuges!

    By bdavis,

    I aspire to be involved in the medical field once i finish my schooling and one of the tools i hope to use is a centrifuge. Centrifuges are tools where test tubes are inserted into spaces around the outside of the tool. It then spins in a circle and the more it spins, the contents in the beakers are separated into their components. The contents in these beakers mostly consist of blood samples and organelles that need to be separated to be analyzed. Centrifuges use the centripital force to separate the components of the samples. The more massive objects/ components in the test tubes experience the greatest force due to the direct relationship between the force and the mass (F= (mv^2)/r). They will be pushed back to the bottom of the test tubes and the fluids along with the less massive components will be on top of the larger organells. When the spinning process of the centrifuge is complete, the smaller and larger components of the sample in the test tubes will be separated. The centripital force incorporated by the Centrifuge is very helpful in allowing medical researchers analyze smaller components of human blood.

  5. bdavis

    Circulatory system

    By bdavis,

    Our bodies conduct physics every second of everyday. Our bodies pump blood. Initially, one may think that the mere action of pumping blood has no correlation with physics at all. On the contrary, the blood in our bodies must be pumped through muscle contraction and applied force as well as pressure. Last year in physics B, we learned quite a bit about fluid mechanics and the relationship between force, pressure and area of the tube the fluids travel through. As our heart initially pumps blood from the heart, it travels through the arteries in the downward direction towards the lower part of our bodies. Not as much energy and force needs to be applied because gravity provides a lot of the force needed to carry the blood through the arteries through the body. That is why the arteries are larger and do not apply as much pressure and force as the veins do. Veins are the other muscular passage way that carries blood but it carries blood back to the heart to be replenished with oxygen. The veins need to carry the blood from the bottom of the human body, against the pull of gravity, towards the heart. Therefore, in order to successfully transfer the blood to the heart, a force greater in magnitude than the force of gravity needs to be applied. F=(P/A) This relationship shows that a smaller area will increase the applied force. The contractions of the veins provide the required pressure and the smaller radius of the veins compared to that of the arteries creates a greater force. That force overcomes the force of gravity so the blood can be constantly circulated within the human body.

  6. bdavis
    Rocket flight is much more difficult and requires much more calculation than it may seem to those not involved in NASA. The more fuel a rocket may have and the more powerful the engine a rocket may have doesn’t always mean it will travel the fastest or the farthest. The heavier the fuel tank, the more the rocket is affected by the pull of the planet’s gravity. Also, the more massive the rocket is, the more it is affected by the air resistance of the planet’s atmosphere. Many calculations go into finding the optimal shape and form for a rocket before constructing it. Rockets cost millions of dollars to construct and they better be able to achieve the intended mission. Also, nose cones and wings are applied to decrease the air resistance on the rocket, making it more aerodynamic.


  7. bdavis
    Rocket flight is much more difficult and requires much more calculation than it may seem to those not involved in NASA. The more fuel a rocket may have and the more powerful the engine a rocket may have doesn’t always mean it will travel the fastest or the farthest. The heavier the fuel tank, the more the rocket is affected by the pull of the planet’s gravity. Also, the more massive the rocket is, the more it is affected by the air resistance of the planet’s atmosphere. Many calculations go into finding the optimal shape and form for a rocket before constructing it. Rockets cost millions of dollars to construct and they better be able to achieve the intended mission. Also, nose cones and wings are applied to decrease the air resistance on the rocket, making it more aerodynamic.


  8. bdavis
    Believe it or not, rubber bands display the law of conservation of momentum very clearly. When a rubber band is pulled back by a person applying a force to it, it doesn't have any momentum because the velocity of the rubber band is zero. So when the rubber band is released, it gains velocity and therefore has momentum. So then how would this action demonstrate conservation of momentum? Well, the rubber band causes the person who released it to experience a recoil force. Since the rubber band is much less massive than a human, the momentum we gain by shooting the rubber band is almost negligible but it still occurs. Therefore when shooting a rubber band, conservation of momentum is demonstrated.
  9. bdavis
    During the AFC football game yesterday night, the wind was blowing really strong from one end of the field to the other. That can be a good and a bad thing for the offenses on each team. The offense driving into the wind will have their quarterback's passes subjected to the wind and his passes won't travel as far. But for the quarterback and his offense traveling the other way, his passes will be thrown with the wind, thus making his passes travel farther with the wind carrying them to some degree. The wind alters the magnitude of the drag force that the air puts on objects in calm conditions. The drag force is given by the equation F= bv or F= cv where b and c are constants of different magnitudes. The wind increases the drag force for the balls thrown into the wind but it decreases the drag force for the balls thrown with the wind.
    Although one team may have had the advantage for part of the game, the Baltimore ravens won and that is all that matters. Harbaugh superbowl!
  10. bdavis

    Dive Vs. Cannonball!

    By bdavis,

    What our dear friend charles merie eckert never mentioned in his series of swimming blog posts was the difference between a cannonball and an actual dive. When asked to visually show another person the difference between a cannonball and a dive, virtually anyone can demonstrate that. But when asked to explain what makes a cannon ball produce a bigger splash than a dive, few people can provide a sufficient response. The reason a cannonball produces a bigger splash than a dive is a greater amount of surface area of a person exposed when he/she hits the water. If the same person jumps off the board with an equal force and reaches the same height, that person will reach the surface of the water with the same acceleration and therefore the same force. But the cannonball causes that same force to be spread over a greater surface area. Therefore the greater amount of water affected by the force will exert an equal force, according to Newton's third law, which produces the splash. In a dive, that force is more concentrated over a smaller area therefore making the resulting splash smaller due to the smaller area affected by the applied force. Now Charles is going to say "well swimming and diving are two different things." He may be right in the technical sense but here we are physicists and that information provides no significant value to what i am explaining. So yes that is the technical explanation as to why a dive is different than a cannonball.
  11. bdavis

    Driving on the highway

    By bdavis,

    There are many sharp turns we encounter when we drive at high speeds on the highways. And even just driving straight down a highway, cars can lose control and accidents can happen. Friction is a concept and a force that plays a huge role in keeping cars on the road. The coefficient of kinetic friction, Meu, is what measures the ratio of the force of friction and the normal force of the object on that surface. It can help us find the maximum speed at which the car can stay stable on the road before it will lose contact. The higher the coeficient of kinetic friction, the higher the maximum speed will be before the car loses contact. Ice and water lower the coefficient of kinetic friction because it makes the surface much more slick and slippery. So on a rainy or snowy day, it is best to go slower because getting in an accident is much more likely in those conditions. Friction is definitely a concept that we should consider in our everyday lives to be safe drivers in all conditions on the road.
  12. bdavis
    i have always been curious how it would be to drop an object from the top of the empire state building. It is obviously a long way down but exactly how fast would an object be traveling once it hit the ground? If i were to drop a golf ball for example, how fast would that travel? Well we can do this using my knowledge of one dimensional motion, a key physics concept. Acceleration due to gravity is -9.81 m/s for any object no matter the mass. Using our kinematic equations we can find out the final velocity any object will attain once it reaches the bottom of the Empire State building. The height of the empire state building is 443 meters tall. That will be our delta Y. Our acceleration is gravity which is -9.81 m/s. Our initial velocity is 0 m/s because we are dropping it from rest. We don't need the time in order to find the final velocity so we will use the equation Vf^2=Vo^2 + 2ay. That will be Vf^2=0 + 2(-9.8)(-443). Vf=93.18 m/s. That would be really fast and could seriously hurt someone. That is really cool!
  13. bdavis
    Here are some of the necessary equations, values, and laws that one must memorize or quickly derive in order to achieve success on the AP-Physics C E & M exam:
    K=(1/(4(pi)(epsilon not)))
    F=(K(q1)(q2))/(r^2)
    E=F/q
    E=(Kq)/(r^2)
    E=(K/r^2)(integral from v to infinity of dq)
    Gauss's Law: Net flux= integral over the closed surface of EdA = Q/(epsilon not)
    V=w/q
    V=Kq/r
    e=1.6X10^-19 C
    a= (qE)/m
    Coulomb's Law:
    The force exerted by one point charge on another acts along the line between the charges. It varies inversely as the square of the distance separating the charges and is proportional to the product of the charges. The force is repulsive if the charges have the same sign and attractive if the charges have opposite signs.
    Rules for Electric Fields:
    1. Electric field lines begin on positive charges (or at infinity) and end on negative charges (or at infinity).
    2. The lines are drawn uniformly spaced entering or leaving an isolated point charge.
    3. The number of lines leaving a positive charge or entering a negative charge is proportional to the magnitude of the charge.
    4. The density of the lines (the number of lines per unit area perpendicular to the lines) at any point is proportional to the magnitude of the field at that point.
    5. At large distances from a system of charges with a net charge, the field lines are equally spaced and radial, as if they came from a single point charge equal to the net charge of the system.
    6. Field lines do not cross. (If two field lines crossed, that would indicate two directions for E at the point of intersection.)

    Depending on the conductor, if it is a shell, solid or hollow, different values of E will be obtained by the properties of the conductor and the radius given in the problem.

    That is the condensed version of the necessary things to know for electrostatics.
  14. bdavis
    du= -F(dl)
    dv=(du/q)
    dv=(-E)(dl)
    delta V= -integral (E)(dl)
    U=qV
    1eV=1.6X10^-19
    U=K(q1)(Q2)/r
    V=KQ/Square root((x^2) + a^2)) (V=0 at abs(X) = infinity
    For a spherical shell of charge:
    V= KQ/r, r>R (V=0 at r=infinity)
    V=KQ/R r
    For an infinite line charge V= 2k(lamda)ln(R_ref/R) for (V=0 at r=R_ref)
    Charge on a Nonspherical conductor:
    On a conductor of arbitraty shape, the surface charge density, (sigma), is greatest at points where the radius of curvature is smallest.
    Dielectric Breakdown:
    The amount of charge that can be placed on a conductor is limited by the fact that molecules of the surrounding medium undergo dielectric breakdown at very high electric fields, causing the medium to become a conductor.
    Dielectric Strength:
    The dielectric strength is the magnitude of the electric field at which dielectric breakdown occurs. The dielectric strength of air is E_max = 3 x 10^6 V/m = 3MV/m

    Not all of the equations are listed because some are required to be derived as parts on the AP test so by knowing the basic relationships and equations, deriving the rest of them become understandable and simple.
  15. bdavis
    F=qVXB
    F=ILXB
    Motion of Point Charges:
    A particle of mass m and charge q moving with speed v in a plane perpendicular to a uniform magnetic field moves in a circular orbit. The period and frequency of this circular motion are independent of the radius of the orbit and of the speed of the particle.
    Newton's 2nd law: qvB=m((v^2)/r)
    Cyclotron period: T= 2(pi)m/(qB)
    Cyclotron Frequency: f= 1/T = (qB)/(2(pi)m)
    Velocity Selector:
    consists of corssed electric and magnetic fields so that the electric and magnetic forces balance for a partivle moving with speed v.
    E=vB
    Mass Spectrometer:
    The mass-to-charge ratio of an ion of known speed can be determined by measuring the radius of the circular path taken by the ion in a known magnetic field.
    Magnetic dipole moment: u= NIAn
    Torque= t= u x B
    Potential energy of a magnetic dipole: U= -u . B
    Net force on a current loop in a uniform magnetic field is 0.
    Biot Savart Law:
    B= (u_0)Lxr/(4(pi)r^2)
    Magnetic field lines: the magnetic field is indicated by lines parallel to B at any point whose density is proportional to the magnitude of N. Magnetic lines do not begin or end at any point in space. Instead, they form continuous loops.
    Gauss's Law for magnetism: Net flux= integral over the closed surface( BdA)= 0
    Ampere's Law:
    Integral over the closed surface (B . dl)= (u_0)I_perm

    These are the main and basic laws and concepts of magnetism. Other equations can be derived for different objects with current flowing through them and deriving them helps to gain a better understanding of the relationships between different objects and their magnetic fields when current is induced.
  16. bdavis

    Equation Dump!

    By bdavis,

    So lately, our physics C teacher has been making us to equation dumps at the beginning of each class. He would give us 4 minutes to write down as many equations as we could, thus seeing how much we had already memorized and how prepared we were for the upcoming exam. To put down as many equations in those 4 minutes not only requires raw knowledge but also strategy involving.... wait for it... PHYSICS!!!:apple: So, the goal in those 4 minutes was to write down 50 equations. That means you would have to average 12.5 equations per minute. That doesn't sound too bad but writing fast helps. Pressing down hard with the pencil increases the normal force which increases the force of friction, thus slowing down the speed at which you are writing your equations. (F=N(mew)) Friction also takes away energy that could be used to maintain a good pace. The work due to friction (w= Fdcos(180) = -Fd) can be minimized if you don't press down hard and lightly glaze over the paper, making sure your equations are down and that you still have enough energy to write more. Thus, you will attain an optimal number of equations, proving to yourself you are prepared if you know your equations. :banghead)
  17. bdavis
    We are now entering our last quarter as seniors in high school. I want to rebound from an uncharacteristically bad academic performance in the third quarter and finish strong in the last quarter. This is now a prime time to start reviewing for the AP test that is looming in the very near future. I for one am quite a bit nervous but I have a plan to follow that will get me prepared for the day of the test:
    1. do 1 blog post a week
    2. Read text book a little bit each night
    3. do webassigns a little bit each night
    4. Read in my review book a little bit each night, reviewing previous units.
    5. get sleep
    6. eat a bagel with peanut butter everyday (got that one!)

    If I do this and take the initiative to begin studying now, I will be able to properly locate my weaknesses, other than the ones I already identified, and I will work to improve them for the day of the test. I will be prepared when I walk in there that fateful day in may. I guarantee i won't look like this:

    and if my pants are down, it will be out of my own accord!
  18. bdavis
    In preparation for the AP Physcis-C exam, I did a number of things that helped me to properly review the year's material.

    1.) I looked over each test and studied the questions that gave me the most trouble.

    2.) I re-read the parts of the text book that described specific properties regarding certain topics during the year such as the properties specific to conducting and non-conducting shells. Also, I looked up and reviewed kirchoff's loop rules and the properties that go along with the circuits in which those rules apply.

    3.) I wrote all of the equations down on separate sheets of paper, one for mechanics and the other for electrostatics and magnetism. And the more i wrote them, the better I recognized them when the day of the AP came.

    4.) I did a little each day and didn't stress myself out too much which helped me to go into the test confident and calm. I set myself up to think effectively and critically for however long we were given for the tests.

    I felt the way I prepared myself for the test was well thought out and it worked pretty well. I probably could have studied the multiple rules and properties better but in the future I know what methods of studying work for me: repetition is the key to my success.
  19. bdavis

    Industrial catapults

    By bdavis,

    We recently built catapults as a project assigned by our physics teacher. Our goal for this project was to maximize the distance of the projectile, which in this case was a softball. We either had the choice of building a catapult or a trebuche but we decided to build a catapult. Using our knowledge of two dimensional motion, we set out to build a catapult that would launch the projectile at the optimal angle with the most applied force. We placed a wooden beam on our catapult at the spot that would cause our arm to release the catapult at 45 degrees, the optimal launch angle. We used garage springs to provide the force to the arm to accelerate the arm until it reached its launch point. We pulled the spring back to the base of the catapult, stretching it a good amount to provide a good source of tension in the spring. That force pulled the arm of our catapult up, launching our projectile at the optimal angle (45 degrees) so it could attain its maximum height and distance. Our catapult launched the softball a maximum distance of 35 yards which was a very solid result to a project that tested our knowledge on a very important physics concept. We were proud of ourselves.
  20. bdavis
    After we took the AP physics C test, we began to experiment with a computer game known as the Kerbal Space Program. In this game, creatures called Kerbals inhabit a planet named Kerbin (surprisingly similar to Earth) and we had to fulfill many missions related to space travel. I really enjoy the Kerbal space program because at the same time it is a fun experience and it incorporates a lot of physics topics such as the incorporation of gravity and air resistance. It also introduces Orbital movement and space flight. I really enjoy the Kerbal Space Program.

    Also, I found the tutorials on YouTube very helpful in understanding how enact a lot of the maneuvers.




  21. bdavis
    As a baseball player well below average height, I need to maximize every aspect of my game to be the best player I can possibly be. One aspect I have tirelessly worked on is my arm strength and throwing mechanics in order to maximize the velocity of throwing a baseball. Velocity is equal to displacement divided by time. Therefore, if there was more displacement over the same period of time, the velocity would be greater. I throw over the top which means that i have more of a windmill throwing motion rather than having a lower trajectory. There is virtually no time difference between the beginning of my throwing motion to when i release it at a 3/4 arm angle (a lower trajectory) or over the top. But by throwing over the top, my arm travels a little bit further and is therefore displaced more. If I apply that same force over the longer displacement during the same time span, then the resulting velocity of the ball when I release it will be greater from my over-the-top motion rather than a 3/4 motion. So I am trying to maximize every part of my game so I make the best of each day of baseball. So basically what I am saying is... come out to support the baseball team! The first game is home against Greece Athena at 4:30pm! Be there!

  22. bdavis

    momentum headaches!

    By bdavis,

    In my soccer game yesterday, I experienced quite a collision. Not with anyone person. I collided with the ball. In soccer, each player is allowed only to use their feet, their body and their head, not their arms or hands. Hands and arms may not come in contact with the ball. Yesterday, I had a few head balls that demonstrate the concept of conservation of momentum. A teammate of mine kicked the ball from the sideline and I redirected it with my head towards the goal. The glancing blow off of my head sent the ball in one direction while my head recoiled and traveled in another. My head, being more massive than the ball, moved only slightly in the opposite direction while the ball flew a good 30 feet to my left. Now, momentum works at angles and the trajectory of the ball was at an angle so its path changed at another angle. My head isn’t a perfectly round surface so the balls new trajectory couldn’t be easily calculated by a normal physics c student, at least without more given information about the dimensions of my head. Needless to say, I left the game with quite a headache.
  23. bdavis

    My Third Quarter

    By bdavis,

    Well I started this third quarter off on a really bad foot when i got an atrocious test grade on the electric potential test. We followed that test with an independent unit in circuits and although my test grade in that unit wasn't anything special, it was a significant improvement. Then we got the magnetism independent unit. In AP-physics B, my understanding of the magnetism unit wasn't very strong but I felt like i had a better grasp of it by the end of last year. However, with an increase in difficulty of the problems and more complex concepts with magnetic monopoles, my mind was blown. I like the freedom we get with the independent units but with freedom comes great responsibility to get it done promptly. I envy my classmates who had took the initiative and got the unit done on time with a better understanding because that is what I should have done. Learning on my own, structuring my schedual, and managing my time is something I must improve as I move on towards higher education.
  24. bdavis

    Opposites Attract ;)

    By bdavis,

    In the dating world, people with opposite personality types seem to be attracted to each other. In the world of electrostatics and magnetism, opposite charges attract each other and opposite magnetic poles attract each other too. Particles with a positive charge, such as a positive test charge, are attracted to particles with a negative charge, such as a negative test charge. The particle with the greater magnitude of charge will attract the other with a greater force. For example, if a particle with positive charge has 2C of charge and a particle with negative charge has 1C of charge, then the particle with a postitive charge will exert a greater attractive force on the particle with negative charge than the attractive force the negative particle will exert on the positive particle. With magnets, the Northern end is attracted to the south end due to opposite magnetic poles. These properties play a very large role in understanding the subatomic relationships between particles of different charge and magnetic polarity in substances such as blood and water. These phenomena occur ever instantaneous moment of everyday!
  25. bdavis

    physics blog post #1

    By bdavis,

    I am very interested in physics and in learning how different things work in the world around us. i class we learned the dot product and cross product and applied them briefly to kinematics in our first day of that unit. Although those are two very new concepts to me relating to vector math, i am interested in grasping the new concepts and applying them to my growing knowledge of physics.
    i wanted to take physics to gain more knowledge about what this area of science has to offer. i am very interested in sciences and i am planning on pursuing a career in medical research in the future.
    i hope to gain more knowledge about physics and being able to apply it to other areas of science to gain a better understanding of how things work.
    i am most excited to go more in depth in the material and better understand electrostatics and magnitism, my two most difficult units from last year.
    i am most anxious to get to apply the knowledge of kinematics to other areas of mechanics and learn more in-depth material.
    I anticipate learning a lot of new things and i am very excited.

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