My Top Ten Physics

Here's to the very last physics blog post I will probably ever do in my entire life. *Cheers* 

The very last blog post criterion says that we should create a condensed version of this year’s lesson into our top ten. Top ten lists can be the best, the worst, or for me a combination of both in regards to what we’ve learned.

At the beginning of the year in my first blog post I said "I believe that studying physics is important because it helps us to understand the world around us, it helps one to increase their knowledge and find interest in things they've never even thought to question about, and physics can help me to understand and maybe even improve my athletic abilities." 

The physics of sports has broad applications, and is useful for boosting performance in a variety of athletic disciplines. A lot of the time, good athletic performance is based on proper control and coordination of movement. Other times, it helps to have a good understanding of the physics taking place, and then using this knowledge to your advantage. So my Top Ten will attempt to follow my course of study and understanding through the relationship of track and field and physics. 

1.    Newton’s first law

Newton's first law of motion states that "An object at rest stays at rest and an object in motion stays in motion unless acted upon by an outside force." Objects tend to "keep on doing what they're doing." In fact, it is the natural tendency of objects to resist changes in their state of motion. This tendency to resist changes in their state of motion is described as inertia. Inertia: the resistance an object has to a change in its state of motion.

Sprinters in track are generally seen starting their race using starting blocks. Starting blocks allow a faster and more efficient starting time. While on the starting blocks they are motionless, then they push back on the block and are now in motion. The runner was at rest then the outside force was pushing back on the block then they are in motion. A runner very rarely comes to a complete stop at the end of a race; rather they continue to run through the line in order to slow down. This concept is also the concept of Newton’s first law or inertia which says that an object in motion stays in motion unless acted on by an outside force.

2./ 2.5 Force- Newton’s second law/ Newton’s third law

When a runner is running they apply a force on the ground. With each step a greater force is applied on the ground which the ground applies on the runner thus propelling them forward. According to Newton’s second law the more mass you have the greater the force needed to propel you forward. Force we learned is the action and reaction of pushing and pulling.

Equation:

Force= mass x acceleration

Newton’s third law states that for every action there is an equal and opposite reaction

(Picture of someone on starting blocks)

A sprinter applies a force to the starting blocks which the starting blocks apply to the sprinter thus propelling the sprinter forward.

3.    Speed

In unit 1 we learned that in order to calculate speed we must know the distance traveled and the time it took to travel that distance. Speed is "how fast an object is moving." Speed can be thought of as the rate at which an object covers distance. A fast-moving object has a high speed and covers a relatively large distance in a short amount of time. Contrast this to a slow-moving object that has a low speed; it covers a relatively small amount of distance in the same amount of time. An object with no movement at all has a zero speed.

Speed is the magnitude of velocity. If you are running in a track competition, it is essential that you are faster than your opponent(s). Speed is also an important factor in field competitions like javelin throws along with discus. Speed affects how far an object or a person travels. The same goes for running speed which is measured by the distance traveled and time it took to travel that distance.

constant velocity = distance/time
constant acceleration
      how far: d= 1/2 at^2
      how fast: v=at
for finding the change in velocity one uses the equation a= change in v/ time

4.    Momentum

Momentum=mass x velocity

P=mv

Momentum is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop them. Momentum is a physics term; that refers to the quantity of motion that an object has. If an object is in motion (on the move) then it has momentum. Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion. The amount of momentum that an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving. Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object. Momentum = mass * velocity. 

The greater the momentum the greater force needed to stop an object. In discus the athlete spins to gain momentum which when the discus is thrown force is applied which propels the discus forward. 

As a long jumper one must run a long lane and then jump by running they gain speed and then exert a force on the ground to propel them farther forward into the pit.

 

5.    Acceleration

Acceleration is the rate of change in the speed of an object.

Acceleration= final speed-initial speed/ time

Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity. Acceleration has to do with changing how fast an object is moving. If an object is not changing its velocity, then the object is not accelerating. Velocity is a vector quantity that refers to "the rate at which an object changes its position." If a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. Every step must go into moving that person further from where he or she started. 

I feel like in terms of track this seems pretty self-explanatory.

6.    Potential Energy/ Kinetic Energy

A runner builds up potential energy when they are in the starting blocks. They build up this energy because they are motionless and they have the potential to move. This energy has the potential to be turned into another energy called kinetic energy. Kinetic energy is the energy an object or in this case runner has while in motion.

7.    Work

Machines help us use our energy more efficiently by reducing the amount of force needed to move an object. In this unit, we addressed simple machines. An example of a simple machine is an inclined plane.

Work = F x d.

The inclined plane, and all other simple machines, increase the distance an object moves, in turn decreasing the force needed to move it. Although the force exerted is decreases, the work will remain the same as it would have been lifting an object over a short distance. 

8.    Electromagnetic induction

You’re probably wondering what electromagnetic induction has to do with track and field or sports in general. I’d like you to know that food has everything to do with sports. In order to purchase this food we generally use credit cards. The food we consume before and after these games are as much a part of the athletic experiences as the athletic experience itself.

Electromagnetic induction is the physics behind how a credit card machine works. A big question this year was how does a credit card machine work? A credit card has a magnetic strip. This magnetic strip is a code. When the card goes into the reader voltage/current is induced due to the coils of wire which when reacting to the credit card change the magnetic field. The computer interprets the electric signals back and forth which ultimately read the card.

! Disclaimer the next one doesn’t really pertain to track and field but it was probably one of my favorite things to learn.

9.    Torque

Torque is created when the line of action of a force does not pass through the center of rotation. Torque is what causes rotation. The lever arm is the perpendicular distance between the line of action of the force and the center of rotation. The torque (τ) created by a force is equal to the lever arm (r) times the magnitude of the force (F). There are three ways to increase torque: 

1.) Increase the force, 2.) Increase the lever arm or 3.) Increase both the lever arm and the force.

Along with the torque, we learned why football players are less likely to be pushed over when they keep their legs shoulder width apart versus their feet being together. This is because when the football players have their feet shoulder width apart; they have a larger base of support, which makes it harder to get the center of gravity from underneath them. When the center of gravity is removed from underneath an object or the player, a lever arm is created which also creates torque and is the reason why the object or person will topple over. The center of gravity is where the average amount of mass is being pulled down on by gravity within an object.

10. Tides

Again this one may seem unrelated to track and field. However, I beg to differ. With their bodies in perfect “summer bod” condition trackletes like to enjoy the sun as well on beaches. The physics of tides are:

We learned that to calculate the force between the sun and the earth and the earth to the moon we had the use the equation F= G(m1m2)/d2, and then we plugged in. We learned that the greater force is between the earth and the sun and confused many of us including myself on how tides are caused. Tides are caused due to the location of the Earth. They are caused by the difference in force which is greater than the sun to the earth. They are caused by the difference in force felt by opposite sides of the Earth. We also learned that distance has a greater effect on the force than a change in mass and that everything with mass attracts everything with mass, and everything with mass has a force. This also relates to your weight on earth, so the closer you are to the center the smaller you are and the farther away you are the more you weigh. There are two types of tides; they are spring tides and neap tides. Spring tides are higher high tides and lower low tides. Spring tides occur when the sun and the moon are aligned. Neap tides are high low tides and the lower tides are higher. Neap tides are when the moon is perpendicular to the Sun and half-moons. 

I couldn’t pass this one up. One of my favorite things I learned this year is completely unrelated to sports.

One of my favorite movies as a child was Brother Bear. A huge part of this reason is that there is a scene that shows the Northern Lights.

During the magnetism unit we learned about the poles of the Earth both geographical and magnetically. We learned that the poles that we know are just geographical while the magnetic poles are actually the exact opposite of these.

The northern lights are actually just cosmic particles being pulled to the poles because of the earth's magnetic field. Because the particles are only entering our sight in two places in the world, the concentration is very high. This is why they are visible. Although the Northern Lights may be harmful I have always wanted to visit them, and still do.

Wind Turbine

 As the year comes to a close we begin to reach our last few blog posts. This blog post in particular is on my classes’ most recent lab of creating a wind turbine. The primary physics concepts needed to understand the function of a wind turbine are:

The turbine is connected to a basic generator which could be either bought as a motor and then turned into a generator (a motor and generator function inverse of one another) or made. In our case we were only allowed to make the generator from coils of wire and a few magnets. The process of creating electricity with magnets is known as electro-magnetic induction. 

Electro-magnetic induction is to induce a current or voltage in a coil of wire by changing the magnetic field around the coil (changing the movement of charges) because magnetism is the movement of charges. The magnet and coil of wire method works because by moving the magnets around the coils of wire the magnetic field changes thus inducing a current in the wire through an alternating current. This change from mechanical energy to electric energy is what makes the wind turbine a generator. This is why the wind turbines were able to work.

The materials needed to make the turbine were:
water bottle
coil wires
disk magnets
square dowel
round dowel
LED
fender washer
screws
wood for the platform
glue

The water bottle was used to make the blades which spun to cause a voltage. In order for the bottle to form this design, we had to cut the bottle. First the top then the bottom then in half, then we placed cardboard pieces to help create the irregular shape.  When this was done, we plunged a hole through the cardboard with a sharpened piece of a round dowel. This round dowel went from the top of the machine to the bottom. The dowel allowed the bottle to spin freely without falling out the frame. We made 4 coils, each of which containing 200 turns. After these were glued down to a piece of cardboard, we used the fender washers and disk magnets to align with the coils that would later help induce the voltage. To do this, we made sure that the poles of the magnets were all facing the same way. When we attached the loose ends of the coils to a LED, we saw that we saw our success when our machine produced enough voltage to show up on the volt meter.  

Hints and Tips for Referencing

Use more than one coil but not too many! My group and I used 4 coils of wire (each about 200 turns) which provided enough voltage to register one of the highest recorded in all the classes. However, using too many coils would be a bad idea. The more coils means more resistance, and the extra resistance will most likely cancel out any extra voltage you might be producing.

If you choose to make the irregular shaped wind turbine my group and I choose you need to be ok with starting parts over. Don’t be intimidated by the water bottle being cut in half or properly placed on the blades. After cutting out one blade which was the perfect size use it to recreate it so your pieces are proportionate. Also don’t be intimidated by using your resources my classmates lades ranged from plastic spoons to perfectly carved cardboard blades.

If you were like my class the magnets were provided. When choosing your magnets choose the smaller ones which are pretty strong (broke a nail trying to get them apart) because otherwise it would be difficult to produce enough voltage that’ll be beneficial.

When making motors (previous post) we were taught to scrape the ends of the wire, because otherwise they wouldn’t be able to conduct a current. Then we used pliers to scrape the wires this time we used sand paper. MADE IT SO MUCH EASIER. So, yes use sand paper to scrape the ends, it will save you so much time and frustration. One a few coils I messed up on originally in length I scrapped them and other groups ended up using them. In this case of needing to increase the length scrape the ends and then scrape the end of another piece of wire by twisting them together, then apply electrical tape over.

This lab is again a learning tool. Therefore do not be upset if you cannot produce a certain amount of energy because you wouldn’t be able to do anything with it anyways. But if you’d like to get closer to creating more energy put more turns in your coils. My groups coils all together were 800 turns and produced the most volts in the class. 

Unit 7 Blog Reflection: Magnetism

Magnetism: 

Finally we have reached the end of the line. The last unit of our regular physics course was on magnetism. The first thing we learned was that the source of all magnetism comes from moving charges.

All magnets have a north and south pole, and their field lines run from north to south inside, and south to north outside. If the magnet is cut in half, it too will form a north and south pole. The Earth is similar in that it has a geographical north and south pole as well as a magnetic field which works the same as a magnet. There is physics behind a compass, because it is a little magnet that can spin freely. The north end of the magnet attracts to the south end of the earth, whiles the south end of the magnet, attracts to the north end of the earth. This attraction causes the needle to align with the earth's magnetic fields. The north pole of the compass points to the correct geographic north because the earth's geographical poles differ from the earth’s magnetic poles.

If something is magnetic or has become magnetized it means that their domains have aligned. Just like vectors add, so do domains. A magnetic field is an area that has become magnetized, and is created when a particle is moving perpendicular to the direction of the fields magnetic force.

The big question for this section was; how does a magnet pick up a paper clip? Domain in the paperclip is random. A domain is a cluster of electrons that are spinning in the same direction. The magnet has a magnetic field. When the Magnet is close to the paperclip thee domains of the paperclip align to match the magnetic field of the magnet. The paperclip now has a north and south pole and the north pole of the paperclip is attracted to the south pole of the magnet and thus the paperclip sticks to the magnet.

The next thing we learned was about motors. We learned about motors by making mini-models which couldn't actually be used a source of power. The motors we made consisted of a battery, paperclips a coil of wire, and a magnet. (the motors we made were similar to the model shown below)

 

When the battery runs a current through the system, the magnetic field creates a torque on the coil which causes it to rotate. You need an AC current for this motor to work, or for most any motor. Motors transform electrical energy into mechanical energy. Moving charged particles feel a force when moving perpendicular to a magnetic field. The force felt by the wire causes a torque. Motors work from the force of the magnetic field.

Magnetic induction is when a magnetic field is created by running a current through coils.

 Electro-magnetism is using magnetism to create electricity. This is found in transformers. A transformer is a device used for increasing or decreasing voltage and transferring electric power from one coil of wire to another through electromagnetic induction. A transformer is made up of two coils of wire; primary and secondary. The primary is the wire directly connected to the power source. The secondary wire is the wire closer to the device being charged. Therefore, the primary is the input, the secondary is the output. Whenever the primary switch is open or closed, voltage is induced into the secondary current. Alternating current (AC) runs through the primary, which causes a change in magnetic field. Direct current (DC) cannot be used, because the current it produces only goes in one direction.

There are two types of transformers; a step up and a step down transformer. They are based on how many turns of a coil each transformer has. If the secondary has more turn than the primary this is considered a step-up transformer, but if the secondary has less turns than the primary it is considered a step-down transformer. The equations for transformers are:

v  Primary Voltage/primary Number of turns = Secondary voltage/ secondary number of turns

v  power is always conserved, power in = power out

v  Voltage x Current= Voltage x Current

v  VI in = VI out

These equations are used in power companies to minimize loses. This is because they can increase the voltage to decrease the current which decreases the loss of electricity to heat.

Electro-magnetism is the physics behind how a credit card machine works; hence the next big question was how does a credit card machine work? A credit card has a magnetic strip. There is a code on the magnetic strip. When the card goes into the reader voltage/current is induced due to the coils of wire which when reacting to the credit card change the magnetic field. The computer interprets electric signals back and forth which ultimately read the card.

Generators have similar design to motors, only its role is reversed. A generator will store mechanical energy as electrical energy. Through electromagnetic induction, generators turn mechanical energy into electrical energy. Generators use resources such as wind or water to turn loops of wire inside of a magnet. 

It relies on the change in the magnetic field rather than the force of the magnetic field. This change in the magnetic field induces voltage which causes current, which is the current we tend to use in our households.

Electromagnetic induction is a way to increase voltage by changing the magnetic field in loops of wire. The change between a magnetic field and loops of wire is what induces voltage. The more loops in a magnetic field, the more voltage, subsequently, the more resistance. When the magnet is inserted through or around the loops, there is a change in the magnetic field of the loops. The induced voltage also means an induced current. The amount of current produced in electromagnetic induction depends on induced voltage, the resistance of the coil and the circuit, and the change in current in a nearby loop. 

Real life applications:

v  In the pavement, at a stoplight there is a loop of wire. When the car, which is magnetic, moves over the wire, it changes the magnetic field of the loop. This change in the magnetic field induces voltage, which causes a current. This current is a signal to the stoplight to change.

v  Metal detectors

v  credit card machines

Conclusion:

The hardest part of this unit for me was to understanding so much material in so little time; especially with creating the motor and understanding the function of all its parts. 

My strongest part of this unit was when we got to transformers and electromagnetic induction, because although I didn’t know the terminology this was information that I kind of already knew. For the test, I will review my notes and the review sheet which we went over as a class.

Motor Blog Reflection

In this current unit the focus of the class is to understand magnetic fields. In this particular section we are encouraged to learn using hands on activities which will later help us in making wind turbines. This section we have created a motor, in which all of its parts functions are vital to the motor actually working. While in this case we have no use for this motor to run things, it was a great learning experience. 

The main parts of the motor include a battery, 2 paper clips, coil, and a magnet. Like my group, some groups chose to use electrical tape to keep the paper clips attached to the battery itself and others, still, chose to use wood and rubber bands to stabilize their motors. The battery is used as a power source to move mechanical energy.The 2 paper clips are used to help carry a current through the battery, which also lead to both ends of the coil.The magnet provides a magnetic field in the motor.The coil is the main part of the motor. The coil is the conductor. The conductor is based off of how many turns in the coil there are and if the coil surrounds an iron core.

We scraped the armature of the coil a certain way because it determines the way the motor spins. If both sides of the coil were completely scraped, the motor would just swing back and forth, rather than making a complete rotation. We strip only one side of the coil and the entire other side of the coil, so that the motor will continue to rotate instead of swinging back and forth which it wants to do. By stripping the armature we have enabled the coil to rotate one way and then let the momentum rotate it back to the top so then energy is put back in and the same thing occurs.

The magnetic field which puts a torque on the coil. The current in the wire create another magnetic field because of the moving charges. The direction of the force is determined by which side of the coil has been fully stripped.

Unit Blog Reflection 6: Charges and Electricty

For the past few weeks Physics regular has been studying Charges and Electricity. During this unit we explored:

-Charges and polarization (which included Coulomb's law)

-Electric Fields 

-Electric Potential/Electric Potential Difference/Capacitors

-Ohm's Law 

-Types of current, source of electrons, power 

  and 

-Parallel and Series Circuits 

The sections of this unit we discussed first were charges, polarization, and Coulomb's law. Coulomb's law is an equation which reads as follows F=k(q1 x q2/ d^2). The F in this equation represents force, the K in this equation is a constant the q’s represent charges, which can be negative or positive, the d refers to distance. The relationship between force and distance is that when distance is doubled force is a fourth of what it was previously. This section also included the transferring of electrons which we learned using the question: why does a balloon stick to the wall once it has been rubbed on your hair? I was unsure of what to expect of this 14 point problem, but we went over it so much that I began to understand its point. The answer to this question is that through friction, the balloon takes electrons from your hair making it negatively charged. As the balloon gets closer to the wall, the wall polarizes which means the protons in the wall are closer to the balloon than the electrons in the wall (which we know because of Coulomb's law). This just means that the protons in the wall have moved closer towards the electrons and the electrons in the wall move farther away. The now polarized wall results in the balloons ability to stick to it.  Another question this unit was how lightning works and how lightning rods work? Lightning works by having negatively charged clouds that get close to the ground. This negative charge polarizes the neutral earth and brings the positive charges closest to the surface of the earth. When the attractive force between these opposite charges gets to be too much a pathway is formed from the cloud to the earth, and the charges rush to the earth creating the flash which is followed by the sound. We use lightning rods to have lightning strike the rods which are more conductive, then the charges travel down a direct path to the Earth, rather than going through the house resulting is little to no damage.

We slowly moved on to studying electric fields, which are the area of influence that a charged object has on other objects around it. They are generally shown with vector arrows which indicate the charge moving within them. Positive charges will have vectors which point outwards, thus repelling other positive electrons. Negative charges will have vector arrows which point outward, thus attracting positive electrons. During this section we encountered mainly large scale problems which included: A positive charged particle finds itself in an electric field. It moves to the left and increases velocity. Is the electric field caused by a positive or negative charge? Many of my classmates and I were tricked by this problem because we can’t know for sure. To answer this problem we have to say that it could be either a positive or negative charge or a combination of the two. Another question we encountered in this section was why electronics are safe in a metal box, and that is because the metal casing works as an electric shielding which causes the charges with the metal to rearrange themselves so that there is no-net charge on the parts within. A Faraday cage is something (usually a metal casing) that disperses charges equally around it so that any object inside will feel no Net Force. This can be seen in computers or other valuable electronics that are protected with a metal case. This is also referred to as Electric Shielding.

In the third section which was Potential difference, electric difference and capacitors we explored voltage, current. Potential difference is just another name for voltage, which is the difference of two currents. Electric potential is very similar but instead it is just on current. A capacitor is a mechanism that gives off a short, strong flash or discharge, this mechanism takes a few moments to recharge. The major question of this section was: was why can something with high voltage be less dangerous than something with less voltage? If few charges with high voltage are being moved, they will not be as dangerous as many charges with low voltages. 

The fourth section of this unit focused on Ohms law, which states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality (the resistance) one arrives at the usual mathematical equation that describes this relationship: V=IR. voltage=(current*resistance).

The next section of unit 6 was types of current, source of electrons and power. The equation for power is Power=IV. This means power equals current times voltage. This equation and that of Ohm's law will be key in a few equations that will be seen in the near future.There are two different types of current. They are AC (alternating current) and DC direct current). An outlet in the wall gives out alternating and AA batteries give out direct current. An outlet that gives out alternating current is commonly seen with a block which converts AC to DC. The two types of circuits are series or parallel. Series is when electronics are placed one after the other in a circuit. This means that if one of the electronics stops working, then the whole circuit will stop working. Parallel circuits are when each electronic device has its own branch in a circuit. In a series, the resistance adds, voltage adds, and current stays the same. In parallel, resistance is cut in half, voltage will always be the same, and current adds. The main question of this section was why does the circuit breaker in Lawrence trip when girls are getting ready for prom? The simple reason is that Lawrence is wired in a series so if one thing goes out all go out. The response that gets you points is that Lawrence is wired in series so the more appliances being used, the less power each one gets, and so when one stops working, they all stop working. One thing we can use to prevent this is a fuse. A fuse regulates the amount of current going through a circuit. Fuses protect household appliances and the wiring of a certain area. This works by having the conductor that bridges the two sides of the fuse being rated for a certain current, when the current gets too high this conductor melts and therefore switches the circuit off. Fuses are wired in series so that when they melt, the whole circuit turns off. This protects wiring as when current rises too high the wires start to combust which is dangerous.

Unit Six was a whole section on energy and electricity. We got to work with light bulbs and learned why a lot of things happened to us like our hair standing up and how lightning worked. While this unit we did not partake in making unit blog reflections we were able to cover an array of topics which all related back to charges and electricity the unit topic and old units. I still don’t understand the point of blog reflections, while for many they help with studying I find them time consuming and hard to complete in the time allotted. I spend most of my time shuffling through what I need to know rather than reflecting on the unit as a whole.

For the most of this unit I sat in class confused on what we were doing and missing class time due to games. Fortunately, I was able to make up for lost notes but still not quite grasping concepts.  For someone who missed class I’d say that my effort improved because I asked questions and attempted to answer many questions and participate in class. My problem solving skills varied based on what the actually problem was but overall my problem solving skills I feel have improved. 

Blog Resource for Current and Ohms Law

Ohm's Law is a statement of the relationship between Voltage, Current, and Resistance in an electrical circuit. It can be represented by the above diagram. Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance, which finishes the usual mathematical equation that describes this relationship, which is I=V/R. I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.

Electric Potential Blog Resource

This video resource helped me in comprehending the small parts as well as the big parts of voltage as a whole. Voltage (electric potential difference, electric tension, electric pressure) as we have learned is the electric potential difference between two points, or the difference in electric potential energy of a unit charge transported between two points. Voltage can be measured in joules, coulombs and volts. This video carefully explains and solves examples on voltage.