ENERGY Making this concept even more inter esting is the fact that energy is not just one thing There are different types of energy The earlier idea of children playing comes in handy when describing the forms of energy For instance there is kinetic energy which is the energy associated with motion Running from third base to home plate while playing baseball is a good example of kinetic energy So are riding a bike and swimming in a pool Then there is potential energy This occurs when an object is positioned in such a way that its energy will increase once it is forced into motion In other words the object has energy because of its potential for movement On the playground a swing set provides an excel lent example of potential energy Pushing a swing puts it in motion creating kinetic energy But at the height of its motion when in a position to be pulled in a downward are by gravity the swing has potential energy Likewise a child sitting at the top of a slide has potential energy before he or she glides down its surface to the ground Kinetic and potential energy are the two most basic forms of energy but there are others Chemical energy is present
INTRODUCTION whenever atoms are combined to form mol ecules which make up the cells of every living thing It is the chemical energy stored in a child's muscles that enable him or her to push a swing or run around a baseball diamond As a bat or tennis racket strikes a ball it gives off heat energy Radiant energy is released by the Sun that shines make ing outdoor play possible while electrical energy is contained in bolts of lightning during a thunderstorm that sends everyone scurrying inside Another interesting fact about energy is that it has the ability to change from one form to another As mentioned before a child sitting on top of a slide has potential energy That potential energy turns to kinetic energy as soon as he or she begins sliding down Within an energy system a group of objects that transfer energy back and forth among themselves energy may move from one part to another but the total amount of energy in the system does not change Studying physics certainly is not child s play meaning it is not simple or unimport ant But with a little imagination the idea of children playing can help make the concept of energy come
CHAPTER 1 ENERGY BASICs TI rock falling off a cliff is different from the same rock lying on the ground below A rubber band pulled taut is different from the same rubber band left slack A glowing lightbulb is different from the same bulb when the electricity is switched off It is the same rock the same rubber band the same lightbulb The differ ence is one of energy Energy is one of the most basic ideas of science All activity in the universe can be explained in terms of energy and matter But the definition of energy is not at all simple since energy occurs in many different forms and it is not always easy to tell how these forms are related to one another and what they have in common One of the best known defini tions of energy is the classical definition used in physics Energy is the ability to do work The many forms of energy include kinetic potential chemical nuclear electrical light heat and sound energy All these types of energy can do work IO
ENERGY BASICs ICE Energy is the difference between the glowing bulb in the center and the dark ones that surround it Shutterstock com ENERGY SSTEMs Energy is readily transferred from object to object especially in the form of heat For this reason it is often necessary to study an entire group of objects that may be transferring energy back and forth among themselves Such a group is called a system The energy of a system is the ability of the entire system II
