Saturday, February 20, 2010


A) This past unit has been the one that I have learned the most from. To start off the unit I learned to use bar graphs as a way to show how energy is transferred. This concept provided a great base for the rest of the unit.  I learned the types of energy storage there are such as elastic, kinetic, gravitational, potential, and dissipated. And how different types of situation have different types of energy. No matter what situation or how much energy, the total amount of energy never changes. Energy can be transferred in many ways. Through work, heating and electromagnetic radiation. Work happens as energy is transferred by forces that cause displacements. When there is a temperature difference between an object and its surroundings the warmer object transfers energy to the colder. Electromagnetic Radiation is when an object absorbs light or loses it. When I make a graph I must show the types of energy in the original system and how it is transferred to different types in the final situation. To do this I must identify what is causing the energy change and then graph them. The difference between the the starting energy and the final one is change in dissipated energy. The process of transferring energy from one system to another is called work. Work measures the amount of change, i.e. change in velocity, in position, size, and shape, that a force produces when it acts on something. Work is a scalar quantity, work does not have direction. Work is equal to product of the force and the distance force is moving or W=Fx. Work can not happen if the distance and the force are perpendicular, no work can be done. The force and the distance must be in the same direction or at and angle(that is not 90 degrees).  Power, or the rate at which the work is done, happens when there is a constant force is parallel to a body in constant velocity. In this unit I have also learned how to how to calculate the amount of kinetic, potential or elastic energy an object has through simple equations such as KE=1/2mv^2, PE=mgh, or PEe=1/2kx^2. In the equation Pe=1/2kx^2, k is the force constant that measures the stiffness of the spring. I have also drawn on things from past units such as net force. The net force equals the change of energy of a body or W=changeKE=changePE. When I find the mechanical energy, that is the sum of all types of energy of a body. This unit is very different from the ones we have done in the past. I have had to learn a whole new set of equations and how to apply them. Usually in the past things have tied more closely to past units but in this unit's problems are vastly different from the ones in the past. How to use the new equations and these new problems have been the most difficult for me, I am not used to the types of things the question is asking me to solve for. Over all this unit was full of new types of problems, new equations, and new answers that I was uncomfortable with at first but over time they have become easier to understand. My problem solving skills have continued to become better. In this section I have had more challenging problems then ever, that I have worked hard to solve. I have tried to understand why I use a certain equation or why I I set PE equal to KE and not just try to get the problem over with as fast as I can. The problem solving strategy listed in the book has helped a lot with this problem.

B)Energy is major part in everyday life. We can see energy in roller coster rides at six flags, when the coster is at the top of the loop it energy is mainly potential, but as it goes down the ramp its energy is all or mostly kinetic. Or when a person is about to jump off a bridge with a rope around them all their energy is gravitational but at the end of the just it is mainly elastic. Or if you push an object across the room you are transferring from yourself to the object. Another example is with a bow and arrow, you transfer energy to the string which then transfers energy to the bow to travel through the air.