Chapter 5: Energy and Energy Resources

Section 1: What is Energy? Energy and Work—working together Energy: ability to do work Measured in SI unit joule

Section 1: What is Energy? Kinetic Energy is Energy in Motion Kinetic Energy: Energy in motion Kinetic Energy Depends on Speed and Mass Kinetic Energy = mv2 / 2 m= mass; v=object’s speed The faster something is moving the more kinetic energy it has. The more massive something is the more kinetic energy it has. Speed has more effect than mass

Section 1: What is Energy? Potential Energy Is Energy of Position Potential Energy: energy an object has because of shape or position Gravitational Potential Energy Depend on Weight and Height Depends on distance from earth’s surface Depends on weight of object Calculating Gravitational Potential Energy GPE = weight x height Expressed in joules

Section 1: What is Energy? Mechanical Energy Sums it All Up Mechanical Energy: total energy of motion and position of an object Could be all potential energy, all kinetic energy or some of both ME = PE + KE When PE increases/decreases KE does the opposite

Section 1: What is Energy? Forms of Energy Thermal Chemical Electrical Sound Light Nuclear

Section 1: What is Energy? Thermal Energy Total energy of particles hat make up an object High temperatures make particles move faster Faster moving particles (more kinetic energy) leads to more thermal energy

Section 1: What is Energy? Chemical Energy Energy of a compound that changes as its atoms are rearranged to form a new compound Form of potential energy Examples: food, gasoline

Section 1: What is Energy? Electrical Energy Energy of moving electrons Form of Kinetic energy

Section 1: What is Energy? Sound Energy Caused by an object’s vibrations Form of kinetic and potential energy

Section 1: What is Energy? Light Energy Produced by vibrations of electrically charged particles

Section 1: What is Energy? Nuclear Energy Energy associated with changes in nucleus Two nuclei join together or nucleus split

Section 2: Energy Conversions Energy Conversion: change form of energy into another Any form can be converted into any other form

Section 2: Energy Conversions From Kinetic to Potential and Back Example—Jumping on a trampoline Jumping—Movement is Kinetic Energy In Air—Gravitational potential energy Trampoline—Stretching is gravitational potential energy Example—Motion of A Pendulum Potential Energy converted to kinetic energy

Section 2: Energy Conversions Conversion Involving Chemical Energy Chemical Energy in food converted to energy for the body Sun’s energy converted into sugar— chemical energy through photosynthesis Carbon dioxide + Water Yields Sugar + Oxygen

Section 2: Energy Conversions Conversions Involving Electrical Energy Electrical energy easily converts to other forms of energy Example: Hair Dryer Electrical Energy Enters—Converts to kinetic energy Electrical Energy—Converts to Thermal Energy Electrical Energy—Converts to Sound

Section 2: Energy Conversions Energy and Machines Machines transfer your energy Energy can be converted to other forms of energy Machines are energy converters Kinetic energy may be converted into other forms

Section 2: Energy Conversions Why Energy Conversions Are Important Making Energy Useful Converts energy to a useful form Making Conversions Efficient Energy efficient—compares amount of energy before conversion with the amount of useful energy after conversion