Through chemistry you have probably learned of the principle of conservation of mass. That is, matter is neither created nor destroyed, but must remain a constant in any interaction. In this chapter we consider the conservation of energy. Initially we will consider only a few of these, but they will enable us to analyze a large number of physical phenomena. The first form of energy is work.
Work is defined simply as a force times the distance over which that force acts.
Thus if a 4 pound book is lifted 3 feet, the work done is 12 foot-pounds. If it takes 7 newtons to slide a box 5 meters along a floor, the work done is 35 newton-meters. It's important to note that if there is no motion there is no work. This conflicts with our everyday English use of the word work which is very personally related. Yowork if your muscles get tired, or if you start to sweat, or if you study late into the night, or if you try hard at a crossword puzzle.