Unit 3 Energy, Work and Power
In this unit, you will be able to: 1.Define and describe concepts related to energy – i.e. types of energy 2.Demonstrate an understanding of energy transformations and how this relates to efficiency 3.Define and describe the physics concepts of work and power and how it relates to energy 4.Demonstrate an understanding of changes of state and how latent heat is involved 5.Analyze the costs and benefits of various energy sources and energy transformation technologies that are used around the world
The Kinds and Forms of Energy Energy is the ability to do work energy is transferred from one object to another whenever work is done energy is always conserved in a closed system energy can be transferred, changed from one form to another, or stored all energy forms eventually become waste heat
Forms of Energy gravitational potential energy potential energy an object has as a result of its distance above a reference point i.e. raising a hammer elastic potential energy stored in an object when its is forced out of shape i.e. sling shotsling shot nuclear potential energy stored in the nucleus of an atom i.e. nuclear fision chemical potential energy stored in molecules i.e. food kinetic energy of motion i.e. riding a bike
thermal energy an object has as a result of the random motion of molecules i.e. boiling water sound energy that is carried from molecule to molecule by vibrations i.e. thunder radiant energy that travels as electromagnetic waves i.e. the sun electrical energy associated with moving electric charges i.e. lightning
Energy Transformations Recall that energy can change from one form to another. i.e. the sun heating a solar powered car radiant energy chemical potential electric energy kinetic energy heat (friction) sound energy More Examples of Energy Transformations Waterslide 1 Waterslide 2 Myth Busters Honda – Rube Goldberg Iphone Rube Goldberg Insane Domino Tricks
Measuring Energy energy is measured by determining the work done or the heat produced whenever work is done, energy is used more energy is always consumed than the work accomplished this is because friction is always present and the energy used to overcome friction becomes waste heat joule (J) kilojoule (kJ) = J (10 3 ) megajoule (MJ) = (10 6 ) gigajoule (GJ) = (10 9 ) 4.1 Prac. #2,3 UC #1,2