Tuesday, May 18, 2010

Electric Circuits: The Final Post

An electric circuit is a pathway for energy transfer. When connected in a closed path, the electric current can travel from a source to an object. However, the circuit MUST have a source, such as batteries. Since the circuit is a closed path, the wiring must connect to both terminals of the source. Electric circuits consist of resistors, batteries, and wires. Ways of measurements include ammeters and voltmeters. An ammeter measures current and a voltmeter measures the voltage across an element of a circuit. There are two types of circuits: series and parellel. However, you can also combine circuits.
In a series circuit, the current is the same at all points, but the equivalent resistance is equal to the sum of each single resistor and the voltage drop sum is equal to the voltage drop across the whole circuit.

In a parellel circuit, the voltage sum is equal to the voltage drop on each branch and the total current is the sum of each resistors' current. Also, the equivalent resistance is decreased each time a new resistor is added to the circuit.

This circuit consists of a series and two parellel. The two parallel resistors are connected in series with the single series resistor on the right. To find the total current, you can combine the parellel circuit's resistance and the series resistances.

Sunday, April 25, 2010

Reflective Pool: Natural Photo

Physics Picture: Natural Photo

            This picture has to do with reflection. The picture is a natural photo because I didn’t stage the picture or manipulate any of the objects involved with it. The frame of the arch is being reflected. The water in this case would be considered a flat surface, such as a plane mirror. With a plane mirror, a virtual image forms under the water’s surface. The light rays from the top of the arch to the water surface reflect at the same angle of incidence. According to the law of reflection, the angles of reflection and incidence are equal. If you extend that reflected ray below into the water, you will see an image that is identical to the object, which in this case is the archway. If you use the ray tracing method in a diagram, the image forms directly below the object. So the image is virtual and the same exact size as the actual object.

Friday, March 12, 2010

Einstein Quote Reflection

"The only source of knowledge is experience." -Albert Einstein

This quote basically means that you don't know something until you have tried it. You learn from your past experiences. If you made a mistake in your past, you learn from your mistake and you don't make the same mistake twice. One cannot assume something unless they have had the experience of doing that something.

For example, someone who's rich (and always has been) doesn't have the experience of not being wealthy. For another example, a student doesn't have the knowledge of what it means to fail if they have only ever gotten "A's" in their lifetime. The quote by Einstein basically says that you don't know something until you have tried it and that you cannot assume! You learn from past experiences, whether they are good or bad experiences. You can either learn from your bad experiences or relive the good ones. You don't have the knowledge of something until you have experienced it.

Friday, February 19, 2010

Reflection: Energy

Part A:

This is what I learned about the Conservation of Energy (COE). I learned that energy is a conserved quantity with the ability to produce change. Energy itself is non-changing, but it can simply be moved around and stored in different ways. In this unit, I learned about different types of energy storage. Some of these different kinds include elastic (Eel), gravitational potential (Eg), chemical potential (Echem), and kinetic (Ek). I also learned about internal energy, which involves friction. Internal energy is often found in the final stage of an energy bar diagram. When energy is transferred, the total amount of energy is conserved, which means the amount is the same and stays constant. Transferring energy from a type of energy storage to another is called "work". I also learned that there are three ways of energy transfer in or out of a system. The three ways are: working, heating, and electromagnetic radiation. During this unit I also learned how to construct a bar graph/energy flow diagram. In the diagrams, I use bar graphs to represent the initial and final energies. Some equations I used in this unit were: W=Fx (if F and d are in the same direction), P=W/t, KE=1/2(mv^2), PE=mgh, and PEe=1/2(kx^2).

I have also had some difficulties in this unit. I often get confused when I should use a net force equation in a problem. When there is a total amount of a certain energy, such as potential energy, I get confused about if I should add up the types of potential energy, such as PEg and PEe. Another thing I get confused about is when I need to find "h" sometimes. When a ramp is involved in a problem, I sometimes do not know when it is necessary to find "h" or "x". I believe that it is possible though to overcome my difficulties with these certain problems.

My problem-solving skills in this unit are a little under where they need to be I think. I feel like my weaknesses involve choosing which equation to use in problems. Some equations seem so similar to me that I sometimes forget they are different, such as the equation for PEe and KE. I feel though that this is just a memorization issue. If I take the time to study and learn these equations, I feel like my problem-solving skills in this unit will improve. My strengths include drawing diagrams for the given problem. Whether the problem involves a bridge, a ramp, or simply a flat surface, I feel like I can draw a diagram sufficiently. I definitely need to work some practice problems though.

Part B:

Energy and everyday life situations are connected in many ways. Every move we make involves energy in some way. For instance, I'll use a rollercoaster as an example. When the rollercoaster is at the top of a hill, it has little to no kinetic energy, but it has a lot of potential energy. Even if you are just mowing your lawn, energy is taking place. You are transferring energy into the lawnmower (at an angle). Energy is apparent everywhere.

Monday, February 1, 2010

Application: Force Glogster

This is my glogster about the forces involved with ice-skating. Click on the link below to find out about forces and what the centripetal force requirement is when ice-skating. My question is: What are the forces involved when someone is ice-skating (at constant speed) around the rink in circles and which one is the centripetal force requirement?
Kira's Force Glogster

Tuesday, January 26, 2010

Reflection: "Circular Motion and Gravitation"

I learned about circular motion, gravitation, and centripetal force. We learned before the difference between scalar and vector quantities, which comes in handy when it comes to centripetal force. Objects moving in a circular motion have a constant speed, but that doesn't mean the velocity will be constant since the object is changing direction. An object traveling at a constant speed in a circular motion is said to be in uniform circular motion. In order to obtain the velocity (m/s), one must figure out the distance and the period. To find the distance (around a circle's perimeter), you would use the equation: 2∏r. "T", the period, is the time that it takes to complete a full rotation. Also, an object is considered accelerating if it is changing direction. In circular motion, it's called centripetal acceleration. Acceleration is perpendicular to the velocity. Also, the inward force that keeps the object in a circular motion is known as the centripetal force. Moving on to universal gravitation, the Law of Universal Gravitation states, "Every object in the universe attracts every other object in the universe with a force that varies directly with the product of their masses and inversely with the square of the distance between the centers of the two masses." There is a lot to know about circular motion and gravitation!

What I have found difficult is drawing FBDs for objects in circular motion. I get confused as to where to place the arrow that describes where the acceleration is going. Also, I sometimes have finger problems when typing universal gravitation equations into my calculator. I believe that these difficulties can be solved over a short amount of time though.

I feel that my problem-solving skills are average. I definitely think that there is room for improvement though! On problems that aren't exactly like ones I have done before, I need to use similar skills used on previous problems rather than freaking out because I haven't seen anything like it. I feel that I am fairly good at figuring out the data I have and the data that I need to find out though. With some more practice, I can get my problem-solving skills to above average!

Sunday, January 10, 2010

Newton's Second Law

Part A:

I learned about Newton's Second Law about acceleration and forces. Newton stated that "for a particular force, the acceleration of an object is proportional to the net force and inversely proportional to the mass of the object." In an equation, this would be a=∑F/m, which could also be seen as ∑F=ma. Newton's Second Law provides a concrete connection between force and acceleration. Also, the directions of acceleration and the force are the same. Also, in this unit, we worked with friction a lot. In order to get the net force used in Newton's Second Law, we sometimes need to know friction. There are two types of friction, static and kinetic. Static friction occurs when objects are at rest, and kinetic friction occurs when an object is in motion. With this information, it was possible to solve problems pertaining to forces and acceleration.

What I have found difficult is knowing what equation to use. I find it challenging to set up an equation sometimes because it confuses me on when to set the equation to equal zero or m×a. Once I figure out the correct equation, though, I can solve the problem without much confusion.

I feel that my problem-solving skills are accurate enough to succeed in honors physics. In other words, my problem-solving skills are average. As mentioned in reflection 1, I sometimes get impatient and frustrated when I can't figure out how to solve a problem. I do, however, feel confident in drawing FBDs and solving for the unknown once I have figured out the equation to use. My weaknesses include occasionally forgetting to multiply the mass by 9.8 in order to get the weight of an object, or visa-versa. I do feel, though, that I can solve the majority of problems without a hitch.