Unit 4 Lesson 1 Energy Conversion and Conservation Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 4 Lesson 1 Energy Conversion and Conservation Florida Benchmarks SC.7.P.11.2 Investigate and describe the transformation of energy from one form to another. SC.7.P.11.3 Cite evidence to explain that energy cannot be created nor destroyed, only changed from one form to another. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Unit 4 Lesson 1 Energy Conversion and Conservation Florida Benchmarks MA.6.A.3.6 Construct and analyze tables, graphs, and equations to describe linear functions and other simple relations using both common language and algebraic notation. LA.6.4.2.2 The student will record information (e.g., observations, notes, lists, charts, legends) related to a topic, including visual aids to organize and record information and include a list of sources used. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Perfect Form What are some forms of energy? Unit 4 Lesson 1 Energy Conversion and Conservation Perfect Form What are some forms of energy? Energy can come in many forms. Mechanical energy is the sum of an object’s kinetic energy and potential energy. Sound energy results from the vibration of particles. This is why sound cannot travel through empty space. Copyright © Houghton Mifflin Harcourt Publishing Company 4

What are some forms of energy? Unit 4 Lesson 1 Energy Conversion and Conservation What are some forms of energy? Electromagnetic energy is transmitted in the form of electromagnetic waves. Electromagnetic waves are produced by the vibration of electrically charged particles. Electromagnetic waves can travel through empty space. Copyright © Houghton Mifflin Harcourt Publishing Company 5

What are some forms of energy? Unit 4 Lesson 1 Energy Conversion and Conservation What are some forms of energy? Chemical energy is the energy stored in chemical bonds that hold chemical compounds together. Thermal energy is the energy an object has due to the motion of its molecules. The faster the molecules move, the more thermal energy the object has. Heat is the transfer of thermal energy. Copyright © Houghton Mifflin Harcourt Publishing Company 6

What are some forms of energy? Unit 4 Lesson 1 Energy Conversion and Conservation What are some forms of energy? Nuclear energy comes from the nucleus of an atom. When an atom’s nucleus breaks apart, or when the nuclei of two atoms join together, energy is released. Copyright © Houghton Mifflin Harcourt Publishing Company 7

Transformers What is an energy transformation? Unit 4 Lesson 1 Energy Conversion and Conservation Transformers What is an energy transformation? An energy transformation takes place when energy changes from one form into another form. Any form of energy can change into any other form of energy. Often one form of energy can change into two or more other forms. Copyright © Houghton Mifflin Harcourt Publishing Company 8

What is an energy transformation? Unit 4 Lesson 1 Energy Conversion and Conservation What is an energy transformation? In a flashlight, chemical energy is transformed into electrical energy. The electrical energy is then transformed into light and thermal energy. Copyright © Houghton Mifflin Harcourt Publishing Company 9

Unit 4 Lesson 1 Energy Conversion and Conservation Is energy conserved? A group of objects that transfers energy only to one another is called a closed system. In a closed system, all the energy is conserved. The law of conservation of energy states that energy cannot be created or destroyed. It can only change forms. Copyright © Houghton Mifflin Harcourt Publishing Company 10

Efficiency Expert! How is efficiency measured? Unit 4 Lesson 1 Energy Conversion and Conservation Efficiency Expert! How is efficiency measured? When energy is transformed from one form to another form, not all of it is turned into useful energy. Usually, some energy is also transformed into thermal energy. Efficiency is the ratio of useful output energy to input energy. Copyright © Houghton Mifflin Harcourt Publishing Company 11

How is efficiency measured? Unit 4 Lesson 1 Energy Conversion and Conservation How is efficiency measured? Energy efficiency is highly desirable because it means as much energy as possible is converted to useful forms. Efficiency is calculated by dividing energy out by energy in and then multiplying by 100 percent. If less energy is wasted, then less energy is needed to operate a machine. Copyright © Houghton Mifflin Harcourt Publishing Company 12

Practice problems % efficiency = (energy out / energy in)100 An old refrigerator required 400 J of energy to give out 50 J of energy. What is its efficiency?

% efficiency = (energy out / energy in)100 A vacuum cleaner uses 120 J of electrical energy. If 45 J are used to pull air into the vacuum cleaner – how efficient is it?