Tuesday, May 18, 2010

Crazy Circuits

A DC circuit, or a direct current Circuit, is one in which all the elments are directly connected and current flows through each. It is essentially a closed loop through which cuurent can flow.

A DC circuit has certain required elements, it must have:

-a supply of energy (such as a battery or other source of energy to provide an excesss of electrons)

-a closed path in which to conduct energy (so that there is a path for electrons to flow)

Examples of DC circuits:

Series Circuit-in a series circuit the resistors are arranged in a series and if the stream of electrons is broken all the elements go off. In a series circuit the current is the same at all points along the wire and the sum of the voltage drops is equal to the voltage drop across the entire circuit. As you can see the current is .45 A along all point and the voltage of one of the light bulbs is exactly half of the voltage of the battery, it both are added together they will equal the total voltage.

Parallel Circuit-In a parallel circuit each resistor provides a new path for electrons so the total current is equal to the sum of the currents through each resistor. Because the elenments are in parallel, the volotage drop is also equal to the total voltage of the source. As you can see the voltage of one of the lightbulbs is equal to the voltage of the battery and the sum of the current is equal to the total current.

Combo Circuit-a combo circuit is a circuit that includes both parallel and series elements and the current in a complex circuit can be found by calculating the sum of the resistence in the parallel elements and adding it to the resistance of the series elements. Then you can use that resistence and the voltage of the battery to determine the current. The rules for the current of series and parallel circuits both apply, in all the series elements the current is the same and the sum of the current of the parallel elements is equal to the total parallel resistence. The same rules as previous circuits also apply to the voltage, the voltage drop of each parallel element is equal to the sum of the voltage in the entire parallel part of the cicruit. for the series part, the voltage for each series elements is equal to the total voltage for the entire series part of the circuit. as seen in the picture below the sum of the amperage in the parallel is equal to the total amerage and also the amperage in the series.the voltage of the series if added to the voltage of the parallel elements will equal the total voltage.

Saturday, May 1, 2010

Water and Waves

What you are seeing in the picture above is a prime example of wave interference. Wave interference is, simply put, what happens when waves traveling in the same medium meet. There are two types of wave interference, constructive interference and destructive interference. Constructive interference occurs when two waves in the same medium tih displacement in the same direction (from the normal) meet. In constructive interference waves can have either a positive or negative displacement from the normal, as long as it is in the same direction. Interference of the Destructive variety occurs when two waves in the same medium that have opposite directions of displacement meet. In the picture above, you can see as the water leaves the Jacuzzi and enters the swimming pool the water makes a series of circular waves when it enters. The waves undergo interference and create the patters seen in the picture. There are both waves crests and troughs and at different point in small disturbances in the water where wave interference between them is occurring. The way the water moves into the pool is an exemplary example of another idea of physics as well. As you gaze down at the bottom of the pool you may realize that the water is casting shadows, but how can water cast shadows if it is transparent? The answer lies in the make up of water itself. Although water is clear it does not let all light pass through it, only 98% of incident light is transmitted through the water. The 2% decrease of light is the reason that the shadows appear.

Saturday, April 24, 2010

Rod Refraction

The rod pictured is not physically bent, but it appears to bend because of the physics principal of refraction, which is the distortion of light waves as they move from one medium to another. Refraction can be categorized with the index of refraction, represented by n.

So, how does refraction create the optical illusion of the bent cleaning rod? Well, as explained earlier, refraction occurs when light goes from one medium to another, in this case from air to water. The light goes from a medium in which it moves fast, the air (n=1), to a medium in which it slows down, the water (n=1.33). As the light enters the denser medium with a higher index of refraction it bend towards the normal (the perpendicular line originating from the spot that the pool rod touches the water. However, I have just said that the light ways bend towards that normal and it looks as if the pool rod is bending away from the normal line, how can both the picture and my statements be true? It is because the appearance of the rod is opposite the direction of travel of light going into the water. As the light enters the water the rays bend towards normal but as the ray exits it bends away from the normal and travels toward your eye at a "lower" angle than the angle that it would approach your eye if the light travelled in a straight line.

Monday, March 22, 2010

Einstein quote reflection

"There are only two ways to live your life. 
One is as though nothing is a miracle.  The other is as though everything is a miracle."

Of the numerous quotations and sayings of Einstein, this is perhaps the most famous and influential. This may be because it is indicative of the human condition and because it so genuinely expresses the contrast between optimism and pessimism. Einstein points out one of the greatest internal conflicts that humans face almost every day in their decisions. This decision is how they decide where to place their mind-set and goals, as well as creating and building hope and determination for a brighter future, and a longer, happier life.
If you look at life, it is truly precious.  To look at life in a negative fashion causes no good things. People only have one life to live, and why should they waste time brooding on the negative aspects of it. People sometimes don’t realize that they have “one life” and each day should be spent wisely. Einstein is trying to tell people that you have to “enjoy the little things” to truly achieve happiness. He is saying that is you treat every small occurrence and victory as something truly great, you will learn to appreciate the big things even more while also increasing your overall vigor and spirit.
            Einstein was not only a physicist; he was a great philosopher as well.  Einstein is overlooked usually as just one of the most brilliant minds of the 20th century. His personality was very deep and people can learn a great deal from his sayings and work. Einstein was the “whole package.” He was able to break barriers in the scientific and mathematical worlds, as well as create life lessons that can change people’s minds and attitudes in a positive direction.

"Imagination is more important than knowledge.
Knowledge is limited. Imagination encircles the world."

Though Einstein said many influential things that have been recorded in history, this quote is one of his most well known and it is one that I think puts in perspective the importance of being yourself and being a free thinker. In this quote einstein is basically saying that if you are creative and inquisitive knowledge will come along with it. He is basically trying to say that though knowledge is important, it is less important than boundless creativity and imagination.What he is really saying is that our knowledge is limited, and that Imagination is the key to unlocking limitless knowledge.

Wednesday, March 10, 2010

Momentum team project

In the glog my Team and I created we showed how Physics related to bobsledding. We diplayed how conservation of energy and conservation of momentum affect bobsleigh and we displayed vector diagrmas to further explain how these concepts apply.

Team 2 Digital tool

Saturday, February 20, 2010

Reflection: conservation of energy

Part A:

This unit we learned about the conservation of energy. We learned that energy is a conserved substance like quantity with the ability to produce change. I also learned that energy can be moved around and stored in different ways but energy itself is unchanged. Energy does not exist in different forms, it is just stored in different ways. While there are not different types of energy, energy is distinguished by the mechanism that is used to store it, such as kinetic, elastic, gravitational potential, and chemical potential. Each of these is not a different type of energy, just a different method for storing energy. As energy is transferred from one method of storage to another, the total amount of energy remains unchanged (this is conservation of energy). energy can be transferred in or out of a physical system in there ways, working (energy is transferred by forces that cause displacements), heating (temperature differences between a system and its surroundings cause energy to be transferred from the warmer object to the cooler object), and radiation (matter loses energy as it emits electromagnetic radiation and gains energy as it absorbs it). I also learned how to represent the transfer of energy with an energy conservation bar diagram. We used bar graphs to represent the initial and final energies and an energy flow diagram to represent what happens during the process of transferring energy. I also learned about work, which is the amount of change that a force produces when it acts on a body. Work is a scalar quantity and its unit is the joule. The rate at which work is done by a force is called power and the unit of power is watts. Power is also equal to the force multiplied by the velocity. After learning the amount of change that a force produces and the rate of that change, I learned about some different transfer methods of energy, namely kinetic energy, potential energy, and elastic potential energy. Kinetic energy is the energy a body has by virtue of motion and is calculated by dividing the product of the mass and the square of the velocity by 2. The gravitational potential energy of a body is found by the product of the mass of the body, the acceleration due to gravity, and its height above a given reference level. elastic potential energy is potential energy associated with elastic materials and is found with the equation PEe=1/2 k(x*x) in which k is the spring constant and x is the displacement. All these transfer methods of energy can be related with work using the work energy theorem. This Theorem states that the net work done on a body is equal to the change in energy of that body, which basically means that Work=change in KE=change in PE. I could then use all these equations to solve problems in which I was given portions of any equation, put them all together and come up with an answer.

The only thing I have found difficult in this unit was when we got into conservation of energy and had problems in which we were figuring out velocity and only being given mass force and displacement. It ocnfused me to come up with the equation for the of the final energy but once I did that I was able to solve the problem much more easily

I feel my problem solving skills have gotten better in this unit, just as they have in units past. The problems we get require us to use critical thinking bacuse not all of them can be approached the same way, and the more practice I have gotten at solving these problems the better my skills have become.

Part B:

The things we learned about conservation of energy are very relevant in real life situations. For example, te physics principles of the conservation of energy are clearly demonstrated in roller coasters. when you are at the top of a ridge in the roller coaster you have x amount of potential energy. When you go down, at the halfway point you have the same amount of energy but now half of it is kinetic and half potential. the instat before the tracks level out and you are almost at ground level, you still have the same amount of energy that you had at the top but now it is all kinetic energy as you are moving (except for a small amount that is internal energy due to friction). Roller coasters clearly show the law of the conservation of energy and demonstarte that energy is only stored in different ways, it does not change forms and is neither created nor destroyed.

Monday, February 1, 2010

physics and Recoil Voki

Get a Voki now!

Dyanmics Application: How is Newton's third law responsible for recoil?

this is a Glog I created to show how recoil is attributed to Newton's third law of Motion. The glog explains why there is recoil and it also talks about why bigger and more powerful guns have more recoil.

edited Dynamics application Glog

Friday, January 8, 2010

N2L and friction reflection

In this unit I learned about Newton's second law of motion and about the force of friction. Newton's second law states the for a particular force, the acceleration of the object is proportional to the net force and inversely proportional to the mass of the object. The direction of the force is the same as that of the acceleration. In equation form this is simply: F=m(a). I learned how to apply the knowledge of the second law to determine mass and value of forces when an object is accelerating. When calculation the sum of the forces for an object that is accelerating just set the sum equal to ma instead of zero. I also learned about apparent weight and discovered that the apparent weight of a body is the force the body exerts on whatever it is resting on. Another thing I learned about is pulley systems and add wood machines. This is where there are two connected objects hung over a pulley, with one possibly resting on a table. I was able to create net force equations for these systems and then find the value of different variable. The final thing I learned about was the force of friction, I learned how to calculate friction and the coefficient of friction (expressed in mu). To solve for variables in these types of problems we used equations from both kinematics and dynamics.

What I have found difficult about what we have studied is the problems containing the coefficient of friction. In these problems you use equations from this unit and the last. Sometimes the answer is not apparent at first but when you keep substituting you are able to cancel out variables. I feel that as I get more practices with these types of problems I will be more comfortable solving them.

My problems solving skills are good in my opinion, and I feel that they have improved over this last unit. During this unit I have had to look at not just what we are learning currently but equations that we learned in the beginning of the year. I had much larger set of possibilities from which I had to choose the rights way to solve the problem. I think I have gotten better at doing this and I look foreword to more opportunities to hone my problem solving skills as the year progresses.