In the Energy Unit I have learned that energy is never created but just reused. Because of that, in one system there will always be the same amount of energy. For example, when someone bungee jumps the system would be the earth, the bungee jumper, and the bungee cord. Before the bungee jumper jumps, quantitatively he has 4 units of gravitational potential energy (Eg) and after he jumps, and is hanging by the cord, he could have 1 unit of Eg, 2 units of elastic energies (Eel), and 1 unit of internal energy (Eint). The most difficult thing about understanding the conservation of energy would definitely be being able to plug in equations with other equations and knowing what to substitute. I am studying all of the equations because being able to quantitatively solve the equations, it is important to know what substitutes for what. I am working really hard to learn all of them before the test. The one that I usually get mixed up is when to use co-sine in the work equations. I just need to remember that when the force (F) and the distance (x) are parallel to eachother you use the equation W=Fx but when they are not parallel but rather at an angle of eachother you use the equation W=Fxcosθ. However I have found reading the problems in this unit a lot more straightforward than in the previous units. Overall, I think that the most important thing to walk away with is that there will always be the same amount of energy in a system. It is a good way to check yourself because no matter what the initial energy will equal the final energy but just in different forms. The energy can transfer to one form or another by moving, being at a height, or preforms work. If it is moving it has kinetic energy (Ek), if it has height it has potential gravitational energy (Eg) and if it a force is being applied to a distance it is doing work, another type of energy.
Over this unit I realized that everything we do uses energy. No matter what you do you will always use energy which I personally find to be amazing. Physics really is everywhere, who would've thought it? One common example among teenagers is car crashes. While a car is moving it has kinetic energy but lets say they hit a wall. All of the energy becomes internal.