Transcript Physics 100 - Astronomy at Western Kentucky University

Physics 100
Energy
Spring 2009
Physics 100 - Energy
Spring 2009
Instructor:
Office:
Phone:
E-mail:
Office Hours:
Dr. Michael Carini
TCCW 229
56198
[email protected]
By appointment
Textbook: Energy and the Environment, 2nd 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