Physics 100 Energy Spring 2009 Physics 100 Energy

Physics 100 Energy Spring 2009

Physics 100 - Energy Spring 2009 Instructor: Office: Phone: E-mail: Office Hours: Dr. Michael Carini TCCW 229 56198 mike. carini@wku. edu By appointment Textbook: Energy and the Environment, 2 nd ed. Ristine & Kraushaar Class Meets: MWF 12: 40 -1: 35 TCCW 236 Course Grade: 3 examinations worth 20% each. Class attendance and participation 10% Homework and in class exercises worth 10% Comprehensive Final Examination worth 20%. Course Description A one-semester survey of the concepts of energy applicable to the understanding of energy in our environment. Topics covered are the nature of energy, sources, transmission, consumption, energy and the environment, and prospects for the future. Experiments will be conducted as part of the classroom work. I expect regular and prompt attendance in this class. Regular attendance is critical to attaining a passing grade in this class. If you need to be absent, do what you can to contact me in advance and for issues involving a visit to a medical professional, please provide verification. General education goals: Through coursework, discussion, readings, reliable resources and empirical exercises Physics 100 introduces the scientific method and critical thinking associated with the impact of science on society that prepares students at Western Kentucky University to understand the relevance and impact of Energy Students with disabilities: In compliance with university policy, students with disabilities who require accommodations (academic adjustments and/or auxiliary aids or services) for this course must contact the Office for Student Disability Services in DUC A-200 of the Student Success Center in Downing University Center. Please DO NOT request accommodations directly from the professor or instructor without a letter of accommodation from the Office for Student Disability Services. Examinations: No makeup examinations will be given unless your absence has been pre-approved or you have a valid excuse (Dr. ’s note, etc) NO LATE ASSIGNMENTS WILL BE ACCEPTED, except for certain cases where you were not in class due to an illness or other verifiable, excused absence.

Physics 100 Weekly Schedule Spring 2009 Week of: Chapter January 26 Energy basics and uses February 2 Energy basics and uses, fossil fuels February 9 Fossil fuels February 16 Heat engines February 23 Test 1, Solar Energy March 2 Other renewable energy sources March 16 Other renewable energy sources March 23 Nuclear Power March 30 Test 2 Energy sources for transportation April 6 Energy sources for transportation April 13 Effects of energy generation on the environment April 20 Effects of energy generation on the environment April 27 Test 3, Conservation May 4 Conservation 1 1, 2 2 3 4 5 5 Last day of Class is Friday, May 8 Cumulative Final Exam Tuesday, Thursday, May 14 1: 00 – 3: 00 pm Note: There is no class March 9 -13 (Spring break) 6 8 8 9 10 7 7

What is Energy? • Physics Definition: The ability to do work • Work: Force applied over a distance (W =f*d) • Force: From Newton, force is the product of a mass and its acceleration (F=ma) also known as Newton’s second law. • But this applies mostly to mechanics, the study of the physics behind an objects motion

What is Energy? • Thermodynamics: the study of the conversion of heat energy into other forms of energy. • In themodynamics, work is defined as the quantity of energy transferred from one system to another without a change in its amount of order (called entropy)

Units of energy • Joules: – The work done by a force of one newton traveling through a distance of one meter; – The work required to move an electric charge of one coulomb through an electrical potential difference of one volt; or one coulomb volt, with the symbol C·V; – The work done to produce power of one watt continuously for one second; or one watt second (compare kilowatt hour), with the symbol W·s. Thus a kilowatt hour is 3, 600, 000 joules or 3. 6 megajoules; – The kinetic energy of a 2 kg mass moving at a velocity of 1 m/s. The kinetic energy is linear in the mass but quadratic in the velocity, being given by E = ½mv²

Everyday examples of the Joule • the energy required to lift a small apple one meter straight up. • the energy released when that same apple falls one meter to the ground. • the energy released as heat by a quiet person, every hundredth of a second. • the energy required to heat one gram of dry, cool air by 1 degree Celsius. • one hundredth of the energy a person can receive by drinking a drop of beer. • the kinetic energy of an adult human moving a distance of about a hand-span every second.

Power • Power: the rate at which work is performed – Or, the rate at which energy is transmitted – Or the amount of energy expended per unit time • • Measured in Watts: • Other units: – HP or horse power – BTUs

Horse power • Arose as a result of the invention of the steam engine. People needed a way to compare the power of a steam engine to that of the horses it was replacing. • Confusing unit there are too many different definitions!

BTU • BTU: British Thermal Units - an energy unit – the amount of heat required to raise the temperature of one pound of liquid water by one degree from 60° to 61°Fahrenheit at a constant pressure of one atmosphere • Used in the power, steam generation, heating and air conditioning industries and the energy content of fuels. • However, BTU is often used as a unit of power, where BTU/hour is often abbreviated BTU. – So you need to watch the context!

Back to Watts…. . • A human climbing a flight of stairs is doing work at a rate of about 200 watts. • A typical household incandescent light bulb uses electrical energy at a rate of 25 to 100 watts, while compact fluorescent lights typically consume 5 to 30 watts. • A 100 Watt light bulb consumes energy at the rate of 100 joules/second. • After 1 hour, this light bulb uses 100 watt-hours • 1 kilowatt (kw) is 1000 Watts