## Sunday, February 21, 2010

### Energy!

A1) This is what i learned about energy. I learned that work is energy transferred by forces that cause displacements. I learned how to do energy flow diagrams and the bar charts that go with them. The bar charts show the transfer of energy from the initial energy to the final energy. I learned the equation for work which is W=Fx, and if F and x are not parallel but F is at the angle with respect to x, then W=Fx cos 0. The units for work is Joules (J). The equation for Kinetic Energy i s KE=1/2mv^2.
The equation for Potential energy is PE=mgh. The equation for elastic potential energy is PEe=1/2kx^2.  Mechanical Energy is the sum of KE and all forms of potential energy, so ME=PE + KE.  Something that i really understood the most though was the conservation of energy and how energy is never lost. Before we started to learn this, i had always thought about that, but never really got it. I understand it now thought that no matter what kind of energy is transfered, it always remains the same.

A2)  What i have found difficult about energy is all of the different equations. There are many equations that have many similar things in each equation. For example, there are 3 equations that have PE in them. This confuses me a lot, but what helps me if just taking it  slow and really understanding what each equation is saying. The most difficult thing for me thought is knowing which energy is present. I have had trouble lately determining which energy is present.

A3) My problem solving skills are a lot better in this chapter than they have been usually. I am more confident and I am taking my time on a lot of the problems. I am also breaking a lot of the problems down piece by piece which helps me a lot. These three questions have helped to solve problems easier: Is the object at a height, 2. Is the object in contact with a spring, and 3. Is a force applied through a distance.  Once i figure out the equation I need to use, it seems so easy. Just plug in the numbers and solve for whatever is needed!

B1) Everywhere i look there is conservation of energy! Bungee jumping, driving up a hill, climbing stair, going down a water slide, or shooting a gun. When at the top of a ski hill, and you are about to ski down the hill without stopping, you have a potential energy. When you are half way down the hill, you still have a potential energy because you still have a part of the hill in front of you, but you also have Kinetic Energy because you are moving. It is cool to know that the Potential Energy you had at the top of the hill is equal to the Kinetic Energy plus the Potential Energy you have when half way down the hill!