The Top Ten Reasons Why We Would Hobos Without Physics

Hobos! Really? I'm so serious. We might not realize it, but physics is a HUGE factor in our everyday lives. Let's look at all at the top reasons why we need physics in our lives to avoid a life of a homeless vagabond. Starting with number ten....

10) We would have no clue what Newton's laws were.

Newton was a great guy. He came up with some pretty important physics concepts that we discussed in class. The three big laws we discussed where Newton's first, second, and third law of motion. Let's get started. Newton's first law of motion was the very first concept we talked about. This law says that every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero net force. The first las is also called the law of Inertia. Inertia is just the tendency of something to resist motion. So, if an object is at rest, it wants to stay at rest. Likewise, if an object is moving, it wants to continue moving. Pretty simple.

Moving on, we talked about Newton's second law. This law says that force is proportional to acceleration. Therefore if the force increases, the acceleration increases and vice versa. Another component to this law is that acceleration is inversely proportional to the mass. Therefore, it there is a large mass, there will be a small acceleration and vice versa. The final equation to represent this law is acceleration equals the force divided by the mass (a=f/m).

Finally, we learned about Newton's third law. This law states that for every action there will be an equal and opposite reaction. Therefore, if I push against the wall, the wal pushes against me. It's pretty straight forward. But if we didn't know anything about this, we wouldn't know the basic facts of life and would therefore have to revert to the life of a hobo.

9)We wouldn't know why magnets and paper clips stick together.

I feel like I've always wanted to know why this happens, but just never have. Physics class has answered some of my biggest questions ever! So first off, every object is made up of domains which are clusters of electrons moving together. These domains are completely random. So starting off, we know that initially the domains in the paper clip are random. The magnet has a magnetic field around it. When this magnet comes close to the paper clip, the domains of the paper clip will align to match the magnetic field of the magnet. The paper clip now has a north and south pole. We know that opposite poles attract. Therefore, the north pole of the paper clip is attracted to the south pole of the magnet; thus the two items stick together. This is a pretty simple concept that we need to know about in life. If we didn't know about this then we would become primitive people and would need to set up a hobo camp away from physics.

8)We wouldn't know about motors in a car

If you're anything like me, you've always thought that motors were something insanely complicated and only an engineer could possibly understand anything about them. WRONG! I know what a motor is and even made one myself. Crazy I know! There are some basic things that are needed for a motor to work; these items are a current carrying wire and a magnet. When I made my motor, I wound the wire into a loop. Ultimately, the current carrying wire felt a force in the magnetic field from the magnet. This force the loop feels will cause a torque. This torque will cause a spin and this can be turned into a car, fan, or even a blender. Personally, I vote for the blender. But if we didn't have motors than we wouldn't have cars and we would have no means of transportation. Thus, we would back pack everywhere and live life as a hobo.

7)We wouldn't know how an ice skater is able to spin much faster when they tucks their body in.

Let's be honest, we have all at some point watched figure skating when there was nothing better on television. Isn't it crazy how when they tuck their body in they go much faster? Well, physics actually explains this. It has to do with rotational inertia. Rotational inertia is just the property of an object to resist change in spin. This also depends on where the mass is primarily located. Another way to explain this is it depends on how far the mass is from the axis of rotation. So, initially, when the ice skater extends their legs out, the mass is away from the axis of rotation. This means that there will be a greater rotational inertia. If there is a greater rotational inertia, it also means that there will be less rotational velocity. However, when the ice skater tucks their body in, their mass is closer to the axis of rotation. This means that there is less rotational inertia and more rotational velocity; thus the skater moves much faster. Hobos don't know about ice skaters though so if we didn't know about this we would be hobos.


6)We wouldn't know what work really is

Personally, I've always thought work was just some job that adults went to every day. In reality, work is a lot more than just that. It is actually a really important physics term. Work is when you exert a force on an object over some distance. The equation to represent this is work multiplied by distance. The one catch is that the force and distance must be parallel to each other. If they are not, then no work will be done. There is also no work done if the object does not move. But if we didn't know this, all paths lead to the hobo life.

5)We would constantly need new coffee cups because they would keep falling off the roof of our cars 

We've definitely all experienced that time when we forget that we put our cup on the car and then when we drive off and it is lost forever. This is actually all because of Newton's first law and inertia. Initially, both the car and the cup are at rest. When the car starts up, it begins to move. Newton's 1st law says that an object at rest wants to stay at rest. Therefore, the cup will want to remain at rest when the car starts. As the car moves, the coffee cup will slide out from under the car and will fall to the ground. But if we didn't even have coffee cups then we would be hobos. This is the truth.

4)We wouldn't know how a credit card machine works

I've always thought that credit card machines worked because of magic and unfortunately that is far from the truth. Credit card machines work because of a process called electromagnetic induction. Basically, electromagnetic induction is when you induce current by changing the magnetic filed in some loops of wire. So based on this we know that we need both loops of wire and magnets for this to happen. In the credit card machine, there is a loop of wire. In the strip on the credit card, there is a series of magnets. As the credi card moves through the wire, it changes the magnetic field of the loop. This change in the magnetic field induces a current in the wire. This current acts as a signal, and tells the computer what your credit card number is. And even though this isn't magic, it's still pretty cool. But if we couldn't access our accounts, we would have no money, and therefore we would be hobos.

3)We wouldn't know why the circuit breaker trips

In life we have been annoyed by a circuit breaker tripping at least once. And while it might be annoying, it is actually very important. Our houses are wired in something called parallel which is just a parallel circuit. A parallel circuit will produce more current as more appliances are plugged in. That's why we can plug any number of things into an outlet and the power will not change between all the objects. However, this can also be dangerous and could cause an electrical fire. A fuse is added to the wiring to avoid this. A fuse is just a little glass container with a piece of wire in it. When the system overheats, the wire in the fuse will heat up and break. Since the wire is broken, the circuit is not complete anymore and no current will flow to the objects. Thus, the electronics will temporarily shut off as the system tries to cool down. If we had no clue about this then our houses would burn down, and then we would have to become hobos.

2)We wouldn't truly know about the north and south pole and therefore santa could never bring us presents

So the north and south poles aren't just places but actually have to do with magnets. In a magnet, the net direction will make a forward and backward and these become the north and south poles. The magnetic field within the magnet will go from south to north and the magnetic field around the magnet will go from north to south. And what is really interesting is that our geographical north is not actually the real north. This means that our north and south pole should be switched. But what really confuses me is whether or not santa lives in the geographical north pole or the magnetic north pole? And if santa is in our life than we would only have one thing to do: become hobos.

1) We would have no clue which horse in the carousel would go faster than the rest

Carousels are possible one of the best inventions known to man, and the best part is there is physics behind it! But before we get into this, we need to know about two different speeds, rotational speed and tangential speed. Rotational speed is the revolutions per minute. Tangential speed (aka linear speed) is the distance covered per time. So in a carousel, the rotational speeds will always be the same for everyone, no matter what horse you are on. However, the tangential speed will be faster for the people on the outside of the carousel because they have more distance to cover in less amount of time. Weird huh? So if you want to have a faster tangential speed, pick a horse on the outside of the carousel, and think about physics! But if we didn't know about carousels we would not only be hobos, but we would be sad hobos!

Final Unit Blog Reflection.

         
 It's finally that time of year: our final unit blog reflection! It's hard to believe that the year has gone by this fast. And we certainly ended on an interesting unit to talk about. In this unit, we talked about magnetism, magnets, north and south poles, compasses, cosmic rays, the "right hand rule", motors, the necessities of making a motor, electromagnetic induction, generators, and finally transformers. Also, some big questions that we answered were why do paperclips stick to magnets, how are the northern lights created, what makes a motor work, and finally, how do credit card machines work.
     
We first started off by talking about talking about magnets and magnetism. Remember, moving charges are the source of ALL magnetism. This concept is key to remember. Generally, electrons tend to spin in random directions; a cluster of these electrons moving together is called a domain. Before magnetism occurs, there is no net direction. However, when something comes into contact with a magnetic field, the domains will align in the same direction as that magnetic field. This net direction makes forwards and backwards distinguishable; these are called poles. The magnetic field inside of a magnet will run towards the north pole and runs away from the south pole. The magnetic field also surrounds the magnet and goes around from north to south. Like poles repel each other and opposite poles attract each other because of the field lines. Attraction is caused by the field lines running in the same direction and repulsion is caused by field lines pointing towards each other. We already know that compasses point north, but because of the knowledge we just acquired, we know that the compass needs to be magnetized for this to happen. Now, lets talk about why a paper clip will stick to a magnet. Originally, the domains in the paper clip are random. The magnet has a magnetic field. When the magnet comes close to the clip, the domains of the paperclip align to match the magnetic field of the magnet. The paper clip now has a north and south pole. The north pole of the paperclip is attracted to the south pole of the magnet. Thus, they stick together.
       
 The next thing we talked about were the northern lights. What this really is are cosmic rays- which are charged particles entering in the atmosphere. As we know, there is a magnetic field running around the earth. When the charged particles try to enter perpendicular to the magnetic field, they will feel a force that prevents them from entering the atmosphere. However, when the particles try to enter through the poles, they enter in a parallel fashion which will mean they feel no force. Thus, northern lights only occur at the poles. However, this means that people there have an increased risk of cancer because the cosmic rays can rip holes in the DNA. Now, lets talk about the affects on wire. Wires have a magnetic field. We can now where this magnetic field points thank to the right hand rule. If you point your thumb in the direction the current is running, your hand should then signify the way that the magnetic field wraps around the wire.

 Next, we talked about motors and even got to build one of our own. We learned that for a motor to work, it needs to have a current carrying wire and a magnet. For my motor, I used a battery, a coil of wire, a paperclip, and a magnet. We use the battery to carry the current. The coil of wire was our current carrying wire. Finally, the paper clip was used to complete the circuit and the magnet provided the magnetic field. Ultimately what happened was the loop of wire turned on top of the battery. This happened because the current carrying wire felt a force in the magnetic field from the magnet. The force the loop feels will cause a torque. This torque will cause a spin. You are turning electrical energy into mechanical energy. This running motor can be used to make a car, a fan, or a blender.

 One of the bigger topics we learned about was electromagnetic induction. We learned that this is when you have a loop of wire and a complete circuit. When you insert a magnet through or around the loop of wire, this causes a change in the magnetic field of the loop. This change ultimately induces a current. Now that we know about this, we can learn about why a traffic light changes when you reach an intersection. In the pavement, there is a loop of wire. On the bottom of your car there are magnets. As the magnets pass through the loop of wire, it changes the magnetic field of the loop. This change in the magnetic field induces a current in the wire. This current acts as a signal to the stoplights that a car has reached the intersection and the light needs to turn green. We can also learn about a generator. When the magnetic field of an object is continuously changing, a generator is made. The generator turns mechanical energy into electrical energy. This will work because the electrons are perpendicular to the magnetic field. This differs from a motor, because a motor turns electrical energy into mechanical energy and the wire must feel a force.

 Finally, we learned about transformers. Transformers are made up of two wires, the primary coil and the secondary coil. The powers are the same in these two coils. The number of turns the coils make is directly proportional to the voltage induced. The more loops there are, the more voltage will be induced and the less coils there are, the less voltage will be induced. AC current will cause the magnetic field to change in the primary coil because AC current runs in the primary coil. AC current runs through transformers. It is important that transformers use AC because otherwise a change in the magnetic field will not occur.

 Personally, I have felt that this unit has been relatively easy. The only thing I initially had a hard time with was learning how a motor worked. But after actually making a motor it made a lot of sense. I am a very visual person and it has been nice to do various experiments in this unit. Otherwise the material has seemed very straight forward to me.

 I feel that my efforts to class and homework have, if anything, slightly increased this semester. I find myself more attentive in class and have felt that as a result my quiz scores have improved. I only hope that this will reflect on my unit test tomorrow. It always seems that I am fine throughout the unit but the day of the test I become overly stressed and end up not doing as well as I could. I do think that my persistance in class this unit has helped me. I still also feel like I take advantage of conference period when I need it. My confidence has also improved because when I answer questions I feel much less stressed out and much more at ease. Ultimately, my goal is to end this school year with a bang. I want to try my hardest on the final exam and get great results for my final grades. I plan to study all the material and take advantage of the review. Hopefully, the material from last semester will come back to my brain. I will try my hardest and ultimately that is all I can do.

I am officially a mechanic

I always thought that creating a motor would be so complicated and only graduates of MIT would be able to achieve this. However, physics class today definitely proved me wrong. I can officially say that I have made my own motor that worked for more than thirty seconds. Now, I'm not saying I'm some sort of genius mechanic, but I do know everything that is involved in making a motor run. Here are the few simple concepts I needed to understand to create a small, running motor. The four things that were essential to the creation of my motor where a battery, a coil of wire, a paperclip, and a magnet. Before I go into detail about what these different items do, I want to remind everyone what we said a motor was. In class, Ms. Lawrence said that a motor was made of a current carrying wire and a magnet. Now that we know this, let's figure out what the purpose of all the items listed above have in the motor. First off, the battery is what carries the current. The coil of wire is what carries this current. We attached two paperclips that were bent to the sides of the battery. These batteries are what completed the circuit from the coil of wire to the battery. Finally, we attached a magnet onto the battery and close to the coil of wire so that it would provide a magnetic field. Once we attached the two bent paperclips to the side of the battery with a rubberband, we needed to create a coil of wire. I wrapped the wire around the paperclip to give it an oval-like shape. Once this coil was created, we needed to do something very important, scrap the plastic coating off the coil loop. We needed to scrape the plastic off because the current would not have been able to go through the coil, and then our motor would not have worked. One of the key things we learned before making the motor was a special hand sign that is illustrated in the picture above. The index finger points in the direction that the current flows. From there, your thumb signifies the directional force and your middle finger represents the magnetic field. This is totally dependent on which way the current is. Based on this hand rule, we knew that our magnetic field would be down below and perpendicular to the current, and then our thumb would be pointing out. The magnet is ultimately what causes this magnetic field. Thanks to our own physics hand sign, we could figure out the directional force and the magnetic field. Thus, we know the current carrying wire will feel a force in because of the magnetic field. The force that this loop feels will cause a torque. This torque will cause a spin. Ultimately, in this process we are turning electrical energy into mechanical energy. So, that is how I, Anna Hart Bassett, built my own motor. There are many things that I could have done with this tiny creation. I could have added wheels to the end and built a small car. I could have attached some fan blades and created a cool fan to use during the hot summer days. However, my personal favorite option is to add some blades to the motor, add some ice cream, milk, and fruit, and create delicious smoothie. It certainly would have been a tasty treat after creating my motor. While there were no smoothies had in class, I did get to keep my wire coil to remember my working motor.

Back to the Basics: Learning About Magnetism with the Science Guy

*the embedding was disabled for this video so here is the link* http://www.youtube.com/watch?v=ak8Bh9Zka50 I know that everyone from our generation will remember watching Bill Nye the Science Guy videos in our elementary school classes. He has a great way of explaining something in simple terms and this is no different today. The attached link is a video that has clips from Bill Nye's episode on magnetism. Not only does Bill reference the north and south pole, as we discussed in class, but also talks about what kinds of things have magnets in them. I personally think it was very helpful to hear about magnetism in the simplest terms. I hope it works for you all as well.

Coming Down the Home Stretch

Another unit has come and gone, but this one has gone on particularly long because of spring break. We took a short break about half-way through the unit, so it might cause some complications for the test tomorrow, but I guess we will see. In this unit we learned about charges, why our hair sticks up when we put on a sweater, why ser, how lightning is created, conductors, insulators, polar, coulomb's law, electric fields and shielding, electric potential energy, voltage, the different kinds of currents, why CFL's are greener than incandescent light bulbs, and why a fuse blows when multiple appliances are plugged in at the same time. To start off, we learned about charges. We know that positive charges are called protons and negative charges are called electrons. When there is an even amount of positive and negative charges in an object, then it is considered neutral. However, when there are more negative charges, the object is negative and vice versa. Opposite charges attract each other whereas like charges repel each other. There are three ways we learned to charge and object. These three ways are by direct contact, friction, or the process of induction. We use these ways to charge an object to explain why our hair stands on end when we pull a sweater over our heads. The sweater rubs against your hair and therefore steals electrons. The sweater most likely becomes negatively charged and likewise the hair most likely becomes positively charged. Because the positive charges want to repel each other, your hair stands up on end to get away from itself. Next, we learned about lightning, how it is produced, and how a lightning rod protects a house from being struck by lightning. Lightning is created when the clouds are charged through friction. The ground is positively charged, and therefore the negative charges from the clouds will attract the ground while the positive charges from the clouds will move away. The negative clouds and the positive ground will eventually attract each other so much that lightning builds up. We learned that lightning moves up and not down. Lightning rods are tall pointy tower that are on top of your house and then run along the sides of your house into the ground. The lightning is attracted to the pointy end of the lightning-rod and will therefore hit it. The energy from the lightning is then directed from the rod, down the side of the house and into the ground. Following this, we learned about conductors and insulators, polarization, and Coulomb's law. A conductor lets a charge move through it whereas an insulator stops the charge from moving. That's pretty simple, but polarization takes things up a notch. When something is "polar" it means that the charges separate and go to the opposite sides of an object. However, the object will still be neutral as long as there are the same amount of protons and electrons. Now let's apply this to using seran wrap. Seran wrap is negative. When it reaches the bowl, the negative electrons go to the wrap and the negative electrons move away. The bowl is now neutral and polar. Another law we use to describe this is Coulomb's law; this law states that the force between any two objects is inversely proportional to the distance. Therefore the farther away something is, the less the force. The equation for this is Kq1q2/d^2. Looking back at the seran wrap example we see that the distance between the attractive charges is smaller than the distance between the like, repelling charges. Thus the force will be greater between the bowl and the attractive forces will be greater than the force between the like, repelling charges and the bowl. Next, we learned about electric fields and shielding. We defined an electric shield as an area around a charge that can push or pull another charge. The negative charges will be pushed out and the positive charges will be pulled in. THe field lines of and electric field indicate how strong an electric field is; when the lines are closer together, the electric field is munch stronger. We then discussed circuit boards to move onto shielding. We learned that a circuit board needs all atoms to be in their proper place. When a negative charge is surrounded by positive charges, the negative charge will feel no force acting on it because the charges counteract each other. It doesn't matter the negative charge's position in the sphere. This is called electric shielding and this helps keep electronics safe. Next, we talked about electric potential and electric potential energy. Electric potential is also known as voltage, and is represented by PE/q; q stands for charge. The electric potential energy is the potential energy of charges. This occurs in like and unlike charges. Most importantly, we learned about the relationship between resistance, current, and voltage. Current is the energy that runs through a circuit and resistance is how easy it is for current to run through this circuit. Based on various experiments we did in a lab, we learned that current and voltage are directly related whereas resistance and current are inversely related. We show this by the equation I=V/R. Finally, we learned about DC and AC, why CFL's are greener than incandescent, and the difference between series and parallel circuits. DC stands for direct current and ac stands for alternating current. The difference between CFL's use less wattage with the same amount of brightness. Finally, we learned about series and parallel circuits. When more appliances are added to a series circuit, the resistance increases and thus the current decreases. However, in a parallel circuit, when more appliances are added, the more the current is, thus decreasing the resistance.

Blast From the Past: CDD

This is a picture from CDD when I was helping my friend Zan get ready. I'm pretty sure we used about five different appliances from hair straighteners to phone chargers. Thankfully, we did not experience the circuit breaker trip, but this tends to happen during dance times because so many electronics are plugged in. Lawrence dormitory is wired in parallel which is what most things are wired in these days. A parallel circuit insures that multiple appliances can be plugged in and all of them can work with a large amount of energy. The more appliances plugged in, the more current that will be produced. This can cause a problem when there are too many appliances causing too much current. This is where a circuit breaker or fuse comes in handy. Both these items shut off the power supply when it detects that there is too much energy. It is attached to an area where the power source flows to all of the different appliances. It is wired in a parallel circuit so that it will cut off the power supplies without anything remaining on. While this might be frustrating when it initially happens, this method prevents electrical fires, so, in the long run, it is extremely beneficial.

The Mouse Has Been Trapped

      "Oh yeah, I can build this mousetrap car with no problem. It will be super easy." These were the thoughts going through my head when I first heard the words mousetrap car project. But after countless hours of work, some blood, some sweat, and many tears I realized I had had not idea what I was getting myself into with this project. However, Margaret Anne and I were eventually successful and the feeling of triumph payed off for all the failure we had endured.

       Our initial plan was to use sewing bobbins for our tires. If you don't know what a bobbin is, it is fairly small. For axels, we used paper clips which did not stay on our car very well. Our lever arm was a piece of plastic that came from one of my hangers that I willingly donated for the cause. This plan failed.....badly. The paper clips constantly fell off no mater how much tape or hot glue we put on and the bobbins were just having problems. The only thing that was a success was the plastic lever arm. With one design out the window, we decided to make a new car with CD's for the back wheels with a piece of a clip attached to the mouse trap itself. Here, we finally started to see some movement. However, this movement was not enough to spark hope in our hearts. Accordingly, we went back to the drawing board. For our next car, we used pencils and lots of hot glue and four CD's. As time went on, we kept getting more and more frustrated. With the final failure of this car, we parted ways in tears. I took the dreaded mouse trap with me, and worked on it till two in the morning, fixing it on the ceramic floors of the bathroom. This ended with a distress call to my mother and many tears. In exhaustion, I decided to end my long day and go to bed. 

         Waking up was easily the hardest thing I had to do that Monday morning. Margaret Anne and I solemnly arrived to conference period in complete frustration. The car was not working no matter the advice we got from Ms. Lawrence, UNCA engineering students, or fellow classmates. We kept trying the car, but with little prevail. Eventually, I left that night with the mouse car in hand, determined to make some progress. For our final design I wrapped tape on two pieces of wire, and then attached the CDs from there so as to keep them stable. We then used screw hooks that attached to our mouse trap (we were able to procure a new one since the previous one was completely covered and glue and not to mention broken). We did not put anything over the CDs at first to see if the lack of friction would make the car go any faster. This actually just made the car turn and move in crazy directions. We then put balloons on the front wheels. We attached the string to the car wound it up, but the car was still not moving five meters. 

        That afternoon, Margaret Anne and I took turns working on the car. She worked on it during lunch and I worked on it during her rehearsal. I tried to modify various aspects to the car, and got it within inches of the finish line. The car seemed to have an equal hatred of me as I had of it. It kept turning in mysterious ways and sometimes wouldn't even go at all. With little hope left, I tried the car one last time and to my great happiness it finally crossed the green finish line! I tried it again to make sure it was really working and....it didn't work. I literally crawled on the floor in tears. Then, I went back in the room, straightened out the wheels and it worked again. Even though I was skeptical, I knew I needed to test the car out one last time, and just like before it did not cross that finish line. When looking at the design of our car, I realized that a piece of hot glue was interfering with our lever arm causing the car to curve in a peculiar way. With this in mind, I removed the glue, and tried the new and improved car. It worked! And with that, I left the physic's room with my head held high.
          Margaret Anne and I encountered various issues in our mouse trap car. For one, our initial wheels were not big enough to propel the car anywhere; they practically weren't able to touch the ground. Also, our string kept getting tangled so we constantly had to reduce the amount of string we had. However, we sometimes had too little string and thus had to add more one. Our lever arm was constantly changing. We tried to make it longer by hot gluing wire to the end of it, but this just weighed the car down. Eventually we prevailed with just the long plastic piece of my well used hanger. Another problem we had was keeping the wheels straight. The CDs constantly wanted to curve which was just not acceptable. We tried to add hot glue to the edge of the hook so as to keep the wheels and the mouse trap in place. However this is how we ran into trouble with the car curving. Once we removed one piece of glue, the car worked and we were the happiest people in the world.
          If I could do this project in the future, I would try to make my mousetrap car even more lightweight to increase the speed of our vehicle. Our car ended up taking seven seconds to cross the five meter mark, but I was so happy that it even made the five meters I didn't care about the time. Next time, I would know how to make our car work, and stabilize the wheels more as wheel. Finally, we had about an 18 inch lever arm, which is a reasonable size. To increase our force, I would increase the distance of the lever arm, but I would try to do this in such a way that the mass would not increase.
          Looking at the Physics applied in this project, we can talk about Newton's 1st, 2nd, and 3rd law. We know that the first law is the desire for objects to either stay in a state of rest or continue moving unless stopped by an outside force.; this is called inertia. Once our mousetrap car started moving, it wanted to keep moving. However, sometimes our lever arm would hit the ground, and this force would cause the car to stop moving. It was times like this that I hated inertia.... a lot. The next law we learned about was Newton's 2nd law which says that acceleration is directly proportional to the force and indirectly proportional to the mass. Therefore, if we had a great force, than we would have a great acceleration. However, if we had a large mass, we would have a small acceleration. Finally, we can apply Newton's third law which says that every action has an equal and opposite reaction. To make our wheels move, we had the string pull on the wheels. If the string pulls on the wheels, the wheels pull on the string and therefore cause movement.
         Friction was a big contributor to our mousetrap car. There are two kinds of friction, kinetic friction and static friction. Kinetic friction deals with two things rubbing together, just like the axel and the wheel. Static friction is the force that opposes a stationary object when something is attempting to move it. We had to consider these frictions with both our wheel and axel, and wheel and the floor. Because we used CDs for wheels, the ends were very slick and the car went out of control. Once we put rubber from a balloon on the front wheels, the car was much more stable and moved in a somewhat straight path. For the wheels and axels, we needed a material that would move but would also cause friction. We used metal rods for axels, and then attached the wheels to the axels by using a large amount of tape. This provided just the right amount of friction we needed.
       Thinking about the wheels we were going to use was hard. We initially thought we wanted small wheels in the front and bigger wheels in the back because then the back wheels would have to go faster because they were covering a greater distance over the same period of time that the small front wheels were. Our bobbin wheels were failures, and in the end we just decided to use 4 CDs. This was actually the best plan because the wheels would cover a greater distance.
       The conservation of energy was ever present in our mousetrap car. We know this law states that energy can neither be created nor destroyed. Therefore, the energy that was put into this car will come out of this car. Before the car was released, the car will have the largest amount of potential energy. Just before the car stops moving, it will have the greatest kinetic energy of the whole experiment. Some of the energy might be turned into heat, but this does not contradict the law of conservation of energy.
        Our lever arm was about 18 inches long. The length of the lever arm directly effects the amount of torque an object has, which is how much an object rotates. The longer the lever arm is, the greater the torque will be. Torque is equal to force multiplied by the lever arm. Because the lever arm was longer, it increased the torque of our car, which was to our advantage. Also, the longer lever arm resulted in a greater potential energy right before the car was released because the spring will have more force on it causing it to store more energy.
         Rotational inertia, rotational velocity, and tangential velocity were also key elements to think about when creating our mouse trap car. If we multiply the rotational inertia and the rotational velocity together, they will equal the angular momentum. If you either increase the rotational inertia, increase the rotational velocity, or increase all of the above, the angular momentum will increase. We also have to consider the conservation of angular momentum; the equation is the rotational inertia multiplied by the rotational velocity before is equal to the rotational inertia multiplied by the rotational velocity after. Based on this equation, we know that if we increase the rotational velocity, we will decrease the rotational inertia which was the best option in this scenario. However, the opposite can happen; the rotational inertia can increase causing the rotational velocity to increase. Moving on, we also have to consider tangential velocity. This is the distance something covers over a certain amount of time. We would like our tangential velocity to be hight, because this means that the wheels will have to move a greater distance over a shorter period of time.
       The last physics concepts we need to take into account are the presence of work and calculating the force, the potential energy, and the kinetic energy. We are incapable of calculating the work the spring does on the car because this force and the distance the car is moving are not parallel; both the distance and force must be parallel for work to be done. We also cannot calculate the amount of kinetic energy because the velocity will not be uniform throughout the experiment. And since we are unable to calculate the kinetic energy, we are therefore unable to calculate the potential energy stored in the spring. Finally, we are unable to calculate the force the spring exerted on the car to accelerate it because the car did not have the same acceleration for every single test trial. Therefore, the spring exerted a different force on the car every time it was released.
       While this project was one of the most stressful projects I have ever worked on, it was also the most beneficial. I learned that sometimes you have to fail many, many times to actually succeed. I wish I could show you the video of our mousetrap car finally moving, but unfortunately the file will not successfully email to me. However, I will tell you this: there was screaming, there was happiness, and there were two girls collapsed on the floor crying tears of joy.

Second Semester Unit 2 Blog Reflection

It's hard to believe that another unit has gone by this semester and it is only February. Our units have been so short that they just fly by. This unit has seemed particularly easy, but I guess we will see how easy it was tomorrow during the test. Not only did we learn about work and power but also their relationship together. We also learned about kinetic energy, potential energy,the change in kinetic energy, the law of the conservation of energy, and machines. To start things off, lets talk about work. Work means that you are exerting a force on an object over some distance. It is equal to force multiplied by distance. Work is measured in joules which is one Newton-meter. We learned that there is a specific relationship between the force and the distance; these items need to be parallel to one another for work to be done. For example, when a waiter is carrying a tray and walking, he is not doing work because his force and distance are not parallel to one another. Also, you have to be moving some distance to be doing work. When you push against a wall, you are not doing work on a wall. However, your muscles are doing work because they are stretching and moving over a distance. You are still exerting a force on the wall, but since the wall doesn't move (or shouldn't move because maybe sometimes it does move) you are not doing work on that wall. Moving on, the next thing we talked about was power. Power is how quickly work is done. It is equal to work divided by time. We measure power in watts which is one joule/second. Here, we also talked about horsepower, which is how much work something does. One horsepower is equivalent to 746 watts. That's impressive! Work and power have a special relationship with each other. Think back to when we did the experiment running and walking up the steps. When we calculated the work for both running up the stairs and walking up the stairs, they stayed exactly the same. This is because neither the force or distance were changed. Work does not depend on time. However, power does. The answers for the power when running and walking up the stairs were very different to each other. Because it took a longer amount of time to walk up the stairs, there was less power done. Accordingly, running up the steps took a lot less time which meant there would be more power. This concept can be complicated to grasp at first, but once you think about it a few times it starts to sink in. Next, we talked about kinetic energy, potential energy, and the change in kinetic energy. We know that kinetic energy is the energy of motion. The equation for this is one half of the mass multiplied by the velocity squared. To calculate the change in kinetic energy you calculate the initial kinetic energy and subtract that from the final kinetic energy. The change in kinetic energy is equal to work. Potential energy is stored energy. To calculate the potential energy, you multiply the mass, the gravity, and the height together. Then, we learned about the law of the conservation of energy. This law states that energy cannot be created or destroyed. It may however be transformed from one form into another, but the total amount of energy never changes. We talked about how in cars, energy is transformed into heat, and that is why an engine heats up. We also talked about this in terms of a ball falling to the ground. Before the ball has started movement, it might have 1000 Newtons of potential energy and zero Newtons of kinetic energy. Then, as the ball reaches the halfway mark, it will have 500 Newtons of potential energy and 500 Newtons of kinetic energy. Then, right before the ball reaches the ground, it will have zero Newtons of potential energy and 1000 Newtons of kinetic energy. The amount of energy will be constant throughout the fall. Finally, we learned about machines. A machine helps decrease the force needed to exert on an object and still keeps the work the same amount. There are two different kinds of work here, the work in and the work out. While both of these final values will be the same, there is still a difference between the two. The work in has a larger distance which results in a smaller force whereas the work out has a smaller distance resulting in a larger force. One machine is an inclined plane or ramps. These ramps help use energy more effectively. There are many other kinds of machines that we use in our every day lives and just might not know it. I feel that unit has gone particularly well. I still think that my confidence in solving physics problems is increasing. One thing I have not done that much in this unit is talk in class. I think that I could benefit from doing this more. Similarly, I have also been thinking of different methods of studying for tests to improve my grades each time. I have been working on a study guide that has all the concepts we studies this unit. It seems to be working well since I feel confident about this material but we will see tomorrow come test time.

Inner Tubing Photo

        This summer, my friend Rachel and I went on a weekend trip to a mountain house with my parents. While there, we went inner-tubing. The course we went down had a similar set up to that of a roller coaster where there are steeper parts and flatter parts. When Rachel and I were about to go down a steep part, we had a large potential energy. However, as we were released down the course, our potential energy decreased and our kinetic energy decreased. This process occurred at every slope. We always had the greatest potential energy right before reaching an incline, and always had the most kinetic energy towards the end of the incline. It was a lot of fun, but the down side was we had to climb up a steep hill every time we finished the course.

Round and Round

It has become a tradition in the Bassett household to go to the fair as a family every fall. As a kid, I always knew we were on the fairgrounds when I could see the ferris wheel poking out for everyone to see. Well, being at boarding school, I missed the fair at home, but was able to go to the mountain fair in Asheville. Like always my mind was drawn to the ferris wheel that overtakes the night sky. Looking back on that day now, I see how I could have applied physics to this very scenario. As we learned, rotating objects will have both rotational velocity and tangential velocity. No matter where you are sitting on the ferris wheel, you will always have the same rotational velocity, which is equal to your rotations per minute. The ferris wheel will rotate the same number of times no matter what. But imagine that there was another row of seats, a row that was closer to the center, or, if you look at the picture, closer to the green area. These two different rows would have different tangential velocities. Tangential velocity measures the distance that you go in a certain time frame. Well, the row closer to the middle would have to cover less distance in a certain amount of time because it is closer to the axis of rotation. The outer row would have to cover a larger amount of distance in the same amount of time because it is much farther away from the axis of rotation. Now, every time the Bassetts go to the fair, all I will be thinking about is the Physics of a ferris wheel.

Starting Off With a Bang

        Well, we are certainly off to a strong start in the spring semester of Physics. It was definitely hard to come back since we had truly done no work, but the experiments we preformed and the lessons we learned certainly made it a lot easier.
        Ms. Lawrence started class off by asking us a question, "Which person will go faster, the person on the outside horse of a carousel or the person the very inside horse of a carousel. Instantly, my brain shut down. How were we supposed to know this? It was beyond any knowledge we had learned before. Thankfully, Ms. Lawrence explained to us that the answer can be answered in two ways. To answer the question, we had to look at both the rotational velocity and the tangential velocity. We learned that rotational velocity was measuring the rotations per minute, and tangential velocity measured the distance covered in a certain amount of time. In the case of rotational velocity, both people were going the same speed. However, when we examined the tangential velocity, we came to realize that the person on the outside was moving faster. This is because they had a greater amount of distance to cover in the same amount of time that the inside horse did. To give an example, recall the propeller experiment we preformed on the first day back to class.
     Next, we watched a video on rotational inertia, and the conservation of rotational momentum. Recall that inertia is the property given when an object resists change in motion. Rotational inertia is basically the same thing with one difference: it is the property given to an object when it resists change in spin. This property is dependent on mass and the distribution of mass. If there is more weight towards the outside of the axis of rotation, then the object will be harder to turn. As an example, think of how runners bend their knees when they are running; this brings the mass closer to the axis of rotation and will ultimately decrease the rotational inertia. Next we have the conservation of rotational momentum. We figured out that rotational momentum is equal to the rotational inertia multiplied by the rotational velocity. We also came to the conclusion that for momentum to be conserved, the rotational momentum before would have to equal the rotational momentum after. We set this equation up just like we did last semester for the conservation of momentum. To learn about the conservation of rotational momentum, we watched a clip on a figure skater pulling her arms in when she spun, causing her to speed up. We figured out that when the figure skater has her arms and leg extended, the rotational inertia will be larger, causing the rotational velocity to be smaller. Looking at the opposite spectrum, when an ice skater tucks her arms and legs in, she decreases her rotational inertia which will ultimately cause her rotational velocity to increase.
       The next subject we talked about was torque. We said that torque caused rotation, and was equal to the force multiplied by the lever arm; the lever arm is just a fancy way to say the distance from the axis of rotation. The larger the lever arm is, the greater the torque will be. To go along with this, we also learned about center of mass and center of gravity. The center of mass is the average position of the total mass on an object or objects. The center of gravity is when gravity is working on the center of mass. Finally, we said that when an object is in a state of balance, it is because the counter-clockwise torque is equal to the clockwise torque.
      Finally, we learned about centripetal and centrifugal force. Centripetal force is a center seeking force; it is what keeps you moving into a curve. Centrifugal force is defined as a center fleeing force, but in reality isn't actually a force at all. It is used to describe that feeling you get when your driving into a curve, like you are about to be flung out of the car. In actuality, there is no force that does this to you.
      I think the biggest challenge coming into this semester was trying to reprogram my brain back into a Physics-thinking mode. I had been so used to thinking mindlessly during break that is was a shock to come back to the classroom. However, my classmates and Ms. Lawrence made it easy on me by taking a slow start and building up from there. We also talked over questions we had.
       In this first unit of the new semester, I feel like my problem-solving skills and effort have increased. I talk more in class and help my partners during labs. I even try to explain to other people that are confused what is going on. My patience has also improved. It is easy in homework questions to try and simply get everything done. However, in reality it pays more to put forth effort, and think through questions that might be confusing. While this definitely increases the time it takes to finish exercises in the book, it is worth it. Second, I feel that as an individual and as a class, our communication skills have improved. We make sure to ask questions when we have them, and even inquire from our neighbors about concepts we don't understand. Finally, I feel that I have started to be more creative in physics, as I think about every day things that pertain to the units we are learning at the time.
      

The Great Mass of a Meter Stick Challenge

        It was a momentous day when Physics F Block walked into class and heard the words "I've got a challenge for you guys today," and a challenge it certainly was. After studying in class lessons on torque, rotational inertia and velocity, and the conservation of angular momentum, we were given the task to calculate the mass of a meter stick only using a 100g weight. Tricky right? My brain exploded just a tad. In my head I was thinking, "How on earth can I do this?!" Thankfully, my partner Margaret Anne had more of a cool head than I did (being a red head has disadvantages sometimes). We thought about the lesson we had just learned on torque, and got to work.
      So thinking about torque, we need to realize that it is equal to the force multiplied by the lever arm; the lever arm is a fancy way of saying the distance from the axis of rotation. We also know that torque causes rotation. Finally, we know that when an object is balanced, like say a see-saw, the counterclockwise torque is equal to the clockwise torque. Thinking this through, we decided that the best step would be to find the lever arm of the meter stick. So, we balanced the weight on the end of the meter stick, and pushed it toward the end of the desk until it was in a balanced state. The meter stick was level at twenty-two inches. We know that a meter stick equals one hundred centimeters, so we could therefore subtract twenty-two from 1one-hundred, and we got seventy-eight.
      Now it got a little tricky (like it hadn't already); we needed to find the lever arm of the other side of the meter stick. To do this, we needed to know the center of gravity, which on a meter stick will always be around fifty centimeters. From there, we subtracted fifty from seventy-eight, and got that the second lever arm would be twenty-eight centimeters. We had all the measurements we needed, but now we had to plug these numbers into an equation.
        As we said before, we know that when a meter stick is balanced (like it was) the clockwise torque is equal to the counterclockwise torque. This gave us an equation to plug our measurements into. Like we said before, we know that torque is equal to the force multiplied by the lever arm; accordingly, our equation became counterclockwise lever arm x force= clockwise lever arm x torque. We said the force on the first side was the weight, so we multiplied that by our twenty two centimeter lever arm. On the opposite side we multiplied our twenty-eight centimeter lever arm by our unknown force. Once we plugged the answer in, our unknown force was 78.57.
         We measured the meter stick and got around 83 grams, which is pretty close to our actual answer. While it was a tough process, it was interesting to use physics to way something without using a scale. It was a good way to wake up our brains in the morning.

Cats and Physics, who knew they had anything in common!

So, when you first watch this video, it is completely understandable that there might be some people out there scratching their heads and thinking, "What did I just watch?" Honestly, if I had not been in a physics class I would have thought the exact same thing, but that was before we learned about the concept of torque. Torque is the name given to the property that causes something to rotate. To get torque, you can multiply the force and the lever arm together; the lever arm is just a fancy way of saying the distance from the axis of rotation. So putting this video into context, we saw the doorstop that the cat was playing with. Based on torque, we know why that doorstop was placed at the very end of the door instead of somewhere in the middle. This was done to increase the distance from the hinge, ultimately increasing the lever arm and thus the torque.

Ice Princess

So I think I probably know what you are thinking right now, "What on earth does a cheesy Disney movie have to do with our physics class." Well, as Margaret Anne and I were talking about in class, Ice Princess is the story of a girl who does a physics project on ice skating. So, to compare this to physics: we know that angular momentum is equal to the rotational inertia multiplied by the rotational velocity. As we talked about in class, when someone spins on skates, whether it's one the ice or at a roller rink, it will always be easier to spin faster when you have your hands and leg tucked in. This is because when you do this, more mass is distributed to the center of the axis of rotation. When this happens, we know that rotational inertia will be less than if you spread your leg and arms out, causing the mass to distributed towards the outside of the axis of rotation. Accordingly, because the rotational inertia is less, then the rotational velocity will be greater causing the skater to go faster.