Physics: Understanding the Properties of Matter and Energy
INTRODUCTION atter and energy are the basic building blocks of the universe Matter is any thing that has mass and occupies space It is made up of particles called atoms and mole cules which means that this book you are holding the water you drink and even the air you breathe have mass Even though atoms have mass most of an atom is actually empty space An atom is made of electrons protons and neutrons The mass of an atom is centered in its nucleus where different numbers of protons and neutrons are combined forming a variety of chemical elements Molecules are groups of two or more atoms The most familiar states of matter are solid liquid and gas but there is a fourth plasma Energy is defined as the capacity for doing work In the early 1900s Albert Einstein theorized that energy and matter are related to each other in a fundamental way He proposed that it was possible to convert matter into energy His theories helped scientists understand nuclear energy Einstein also understood that the reverse was possible convert ing energy into matter though this is difficult to achieve because of the large amounts of energy that are needed Energy can be categorized into two basic types kinetic and potential Kinetic energy is energy of This girl and the skateboard she is on are made of matter and they are demonstrating kinetic energy the energy of matter in motion Purestock Thinkstock
PHYSICS UNDERSTANDING THE PROPERTIES or MATTER AND ENERGY motion A bird flying through the air and an arrow shot out of a bow both have kinetic energy Potential energy is energy that is stored up but not yet used A rubber band that has been stretched out has potential energy As soon as it is let go that energy becomes kinetic because it is in motion The water behind a dam also has potential energy which becomes kinetic energy when water released from a dam rushes out In this book you will learn about the fun damentals of matter and energy and how physicists have discovered the basic building blocks of the universe and their properties You will also learn about the prominent scientists who have made these discoveries tested theo ries and given us a wider view of the known universe all by looking at its most basic parts 10
CHAPTER 1 WHAT IS MATTER n electron a grain of sand an ele phant and a giant quasar at the edge of the visible universe all have one thing in common they are composed of matter Matter is the material substance that makes up the physical universe A beam of light the motion of a falling stone Large elephants and the tiny dust specs that they kick up are all made of the same substance matter Johan Swanepoel Shutterstock com 11
