TABLE OF CONTENT S What is Physics 4 Energy 5 Mass Length and Time 5 Motion and Force 6 Motion 6 Force 6 The Four Fundamental Forces 7 Velocity and Acceleration 8 Newton’s Three Laws of Motion 10 Friction 12 Circular Motion 13 Gravity 15 Energy 17 Work 17 Simple Machines 17 Forms of Energy 23 Conservation of Energy 23 Potential and Kinetic Energy 24 Momentum and Collisions 26 Electricity and Magnetism 27 Electric Charges 27 Current 30 Magnetism 32 Heat 36 Temperature 36 Expansion and Contraction 37 How Heat Works 40 The Uses of Heat 41 Waves Sound and Light 43 Waves and Sound 43 The Nature of Light 45 Where Light Comes From 48 Reflection and Refraction 48 Nuclear Energy 52 Uses of Nuclear Energy 53 Fission and Fusion 54 People Who Study Physics 60
What Is Physics S Physics is the science of how the universe works It is a science based on experiments observation and measurement Experiments involve making things change Observation is when scientists watch what they are studying very carefully Measurement is describing things by their weight size or temperature Physics looks at how tiny atoms are put together Atoms are tiny particles that make up everything in the universe Physics looks at how huge planets and stars move It helps scientists understand the way matter acts Matter includes the solids liquids and gases in the universe Physics also helps scientists understand how energy acts C I S Y H P S I T A H W PHYSICS A physicist uses precise measurements The protons and neutrons in the nucleus of an atom are surrounded by a cloud of electrons Astrophysicists are physicists who study the stars and planets 4
5 PHYSICS W H A T I S P H Y S I C S Energy Energy is everywhere Energy is the ability to do work It takes on many different forms Energy is stored inside atoms Light and sound are forms of energy People who study physics study how energy is used They study how energy changes Scientists are constantly improving the understanding of the basic or fundamental laws of nature New discoveries are being made every day These discoveries have a big effect on how people live and what they do Mass Length and Time The laws of physics can be described in simple terms These terms explain the way the universe works Scientists use units of measurement to describe what they do This is done so that all scientists can understand each other’s results The three fundamental units of measurement they use are mass length and time Plants get their energy from the sun Animals get their energy from plants or from eating other animals Mass measures the amount of material in an object Length measures how long something is Time measures how long changes take Mass Length and Time atom AT-uhm very small part of an element energy EN-ur-jee the ability to do work experiment ek-SPER-uh-ment trying to make substances change and recording what happens matter MAT-ur anything that takes up space and has mass size measurement MEZH-ur-ment saying how big something is how much it weighs or how hot it is observation ob-zur-VAY-shuhn when scientists watch what they are studying very carefully and write down what they see physics FIZ-iks the study of matter and energy
6 PHYSICS M O T I O N A N D F O R C E In physics the International System of Units is used to measure things This system is based on the metric system The metric system uses specific units of measurement The International System Unit of mass is the kilogram The basic unit of length is the meter The basic unit of time is the second Scientists can describe almost everything by using these units in different combinations Motion Everything is in motion Both small things and big things move People and animals move about on the surface of the Earth The Earth itself rotates turns and moves in an orbit circles around the sun The largest view that we can have is to look at the entire universe Scientists often choose a certain point of view or frame of reference when studying physics This allows them to study specific actions in the universe Force Forces are at work everywhere A force is anything that affects the movement or shape of an object Objects can be so small that you cannot see them with the naked eye They can be bigger than planets Kilogram kg used to measure mass Meter m used to measure length Second s used to measure time International System of Units International System of Units in-tur NASH-uh-nuhl SISS-tuhm uhv YOO nitz a standard way of measuring something force forss what causes something to change its speed or it’s direction of movement mass mass the amount of material in an object metric system MET-rik SISS-tuhm a system of measurement based on tens that uses basic units such as the meter liter and gram motion MOH-shuhn when something is moving Motion and Force The water in a river is in constant motion
