Transcript Aim: What is work?

Date: 11/16/2007
Friday
Aim: What are 5 main forms of Energy?
Do Now: 1. What is work?
2. What are units of work?
Homework: Have a great weekend!!!
What is Energy? • The ability to do work
• Measured in Units of
Joules
What are the 1. Chemical:
5 main forms the energy found in the bonds
of Energy?
that hold atoms together
• When bonds are broken, energy
is released
• Example: fossil fuels (oil, gas,
coal), food, a battery
2. Heat:
• Associated with the internal motion of
atoms
• Causes change in temp. & phase changes
• Usually results from Friction
3. Electromagnetic:
Energy associated with moving charges
called electrons
Examples: electricity, light, x-rays…
4. Mechanical:
energy associated with motion
Examples: Sound, moving water, wind…
5. Nuclear:
• energy associated with the
nucleus of an atom
Ex) Radioactive Substances have unstable
nuclei that breakdown
• When the nucleus splits (fission) heat &
light are released
• When hydrogen nuclei collide & fuse to
form helium fusion occurs (Sun)
• The most concentrated form of energy
Date: 11/19/2007
Monday
Aim: How does Potential Energy compare to
Kinetic Energy?
Do Now:
1. Take out homework.
2. Handout
Homework: Read pgs 128-133 & Define the 9
Vocabulary Words on the top of pg 148
(Using Vocabulary)
What is • Stored energy or energy of
Potential
position
Energy? • Example: Stretched rubber
band, or compressed spring
What
What
happens
happensto
to • Gravitational Potential Energy
GPE
GPEas
as
What
weight
G.P.E. = Weight X Height
heightis
weight?
increases?
increases?
What is • Energy of Motion
Kinetic
• K.E. = mass x velocity2
Energy?
2
What happens
What
happens
is
toWhat
K.E as
to K.E as
velocity?
mass
velocity
increases?
increases?
Which Rubber Band has Greater
Potential Energy?
Which picture
demonstrates
Potential Energy
& what picture
shows Kinetic
Energy?
P. E.
K.E.
Why doesn’t the
still ball have
Energy at the
bottom of the hill?
Date: 11/20/2007
Tuesday
Aim: Lab – What is the difference between
potential & kinetic energy?
Do Now: Handout (Ball: K.E. vs. P.E.)
Homework: Complete Lab questions.
1. Where is Potential
Energy the greatest?
2. Where is Kinetic
Energy the greatest?
3. Where is the least
K.E.?
4. Where does
K.E. = P.E.?
Date: 11/21/2007
Wednesday
Aim: 1. What is the Law of Conservation of
Energy?
2. How did you do on your Work &
Machines Exam?
Do Now: Take out homework (lab)
Homework: Have a Happy & Safe Thanksgiving!!!
Study for quiz on Energy (Next Tuesday)
What is the
• Energy can neither be
Law of
created or destroyed by
Conservation ordinary means
of Energy?
• It can only change from
one form to another
(During the change some
energy is always converted
to heat.)
1. Where is Potential
Energy the greatest?
1
5
2
3
4
2. Where is Kinetic
Energy the greatest?
3. Where is the least
K.E.?
4. Where does
K.E. = P.E.?
0.10 N
0.22 N
Inclined Plane
35 N
2m
50 N
DE/DR = 2m/1m = 2
FE X DE = 35 N X 2 m = 70 J
FR X DR = 50 N X 1 m = 50 J
Woutput / Winput X 100 = 50/70 X 100 = 71%
Date: 11/26/2007
Monday
Aim: What are energy conversions?
Do Now: Compare Potential to Kinetic Energy.
Homework: Study for tomorrow’s Quiz (Energy)
Example:
What are
• Chemical energy in gasoline is
energy
conversions? transformed into mechanical
energy in an automobile engine.
• Energy, in the form of heat, is
almost always one of the
products of energy
transformations.
P.E. is converted into K.E. &
K.E. is converted into P.E.
A
B
A-B
B-C
C-D
D-E
E-F
P.E. decreases as K.E. increases
P.E. increases as K.E. decreases
P.E. decreases as K.E. increases
P.E. increases as K.E. decreases
P.E. decreases as K.E. increases
Chemical Energy
to Light & Heat
Energy
Mechanical Energy
to Mechanical
Energy (Sound)
Mechanical
Energy to
Electromagnetic
Energy (Light) &
Heat Energy
Electromagnetic
Energy (Light)
to Chemical
Energy
Date: 11/27/2007
Tuesday
Aim: What is the difference between nonrenewable & renewable energy resources?
Do Now: Prepare for quiz.
Homework: pg 512 (1-14) Use complete sentences.
Energy Quiz
(Choose: Chemical, Heat, Electromagnetic, Mechanical,
or Nuclear for your answers)
1. Sound is a type of _________ energy.
2. When atomic bonds are broken, _______ energy is
released.
3. Energy associated with motion is called ______
energy.
4. The internal motion of atoms is called _______ energy.
5. Light & electricity are forms of _________ energy.
Non-Renewable Energy Sources
• Fossil fuels:
coal, oil, petroleum, and natural gas
• Considered non-renewable because humans
use them faster than they can be made
(they take millions of years to make)
• These are a major source of energy in the
U.S.
Problems With
Non-Renewable Energy Source
• When fossil fuels burns, they release carbon
dioxide gas.
• Increases in CO2 creates the “Greenhouse
Effect” which is associated with Global Warming.
• Global Warming melts polar ice caps & raises
water levels leading to flooding & strange
weather patterns.
• The burning of coal also contributes to making
sulfuric & nitric acids which make acid rain.
Problems With
Non-Renewable Energy Source
• Transport of fossil fuels has also been associated
with oil spills that directly kill wildlife or damage
the wildlife’s environment.
Renewable Energy Source
• Examples:
Sunlight (a major source of energy for the
earth), wind, falling water, tides, geothermal,
& biomass
• Each of these create very little or no pollution
• Wood (biomass) can be considered a
renewable energy resource as long as trees are
replanted.
Solar Energy
• Photovoltaic cells convert solar energy directly
into electrical energy. Ex) solar calculator
• The heat from the Sun can also be used to boil
water to create steam to turn a turbine & make
electricity
Wind Energy
• As the Sun strikes Earth, the atmosphere is
unevenly heated creating wind.
• Wind energy can be used to turn the turbines of a
generator producing electricity.
Hydroelectric Energy
• Moving water can turn a turbine to create
electricity.
• Water can be heated by burning biomass
(wood, manure…), geothermal energy, or
the sun to create steam.
• Steam can also turn a turbine to create
electricity.
Geothermal Energy
• In the middle of the earth is hot liquid rock called
magma.
• The heat from inside Earth, can be used to heat
homes or boil water to create steam that drives
turbines.
Date: 11/28/2007
Wednesday
Aim: How is matter affected by heat?
Do Now: 1. Take out homework.
2. What is matter?
3. What is heat?
Homework: Read pgs 260-265 Answer Self-check
Questions (1-3) on pg 265.
What is
matter?
• Anything that has mass &
takes up space
(volume)
1. Solids:
What are 3 phases
• Have a definite volume &
of matter & their
shape
properties?
• Particles are tightly packed
together & vibrate in place
(least K.E.)
2. Liquids:
• Have a definite volume, but
take the shape of its container
(particles can slide past each other:
attractive forces are weaker)
3. Gases:
• Have no definite volume or
shape
What are 3 phases
of matter & their • Particles are very far apart
properties?
& move the fastest
• Attractive forces = weakest
4. Plasma:
• No definite shape or volume
• Exists in very high temps. (ex)
stars & lightning)
• Charged particles
• Thermal Energy
• Caused by the internal motion of
What is particles of matter
heat? • Always flows from areas of
Hot (warm) to Cold (cool)
Until both areas reach the same temp.
• Addition or removal causes phase
changes to occur (physical changes of
matter from one state to another)
Where will the heat flow?
A. 20º C
C. 38º C
B. 15º C
D. 65º C
Which has the most heat energy?
Date: 11/29/2007
Thursday
Aim: How does heat affect temperature?
Do Now: 1. Take out homework.
2. Are phase changes physical or
chemical changes? Why?
Homework: Read pgs 254-259 & Answer self-check
questions (1-5) on pg 259.
• The measure of the motion
What is
(avg. kinetic energy) of
temperature?
molecules in a substance
When does water have a greater K.E.
at 50º C or 70ºC?
How does heat 1. When heat is added avg. K.E.
increases (molecules move
effect the
faster & spread apart) &
temperature of
temp.
increases
a substance?
2. When heat is removed avg.
K.E. decreases (molecules
move slower & usu. closer
together) & temp. decreases
• Most substances expand when heated &
contract when cooled.
• Water is an exception, expanding when
changing to ice.
• Temperature also affects the solubility of
some substances in water.
Phase Change Movie
Celcius
Freezing
pt. of
What are
water
some
Boiling
important
temperatures? pt. of
water
0º C
Fahrenheit
Kelvin
32º F
273 K
100º C 212º F 373 K
Body
Temperature
37º C
Absolute
Zero
-273º C
98.6º F 310 K
0K
How can you Heat gained or lost =
find the
Mass x ΔT x Specific Heat
amount of heat
(Δ = change)
gained or lost Units = calories
by a sample of
water?
Specific Heat =
The ability of a substance
to absorb heat
1) The temperature of a 10 gram sample of
water increases from 20º C to 40º C. How
much heat energy did it gain?
Heat gained = Mass x ΔT x Specific Heat
Heat gained = 10 g x 20º C x 1 cal/g. º C
Heat gained = 200 calories
2) The temperature of a 5 gram sample of
water decreases from 50º C to 45º C. How
much heat did it lose?
Heat gained = Mass x ΔT x Specific Heat
Heat gained = 5 g x 5º C x 1 cal/g. º C
Heat gained = 25 calories
Date: 11/30/2007
Friday
Aim: What are various types of phase
changes?
Do Now: 1. Take out note-packet & homework.
2. What is absolute zero?
Homework: Study for next Thursday’s Exam on
Energy & Heat.
Handout (phase changes)
Absolute Zero:
K.E. = Zero
No Molecular Motion
Adding Heat
sublimation
What are
the various
types of
phase changes?
melting
S
vaporization
L
G
freezing condensation
deposition
Removing Heat
sublimation example:
Dry Ice (solid) changes to CO2 (gas)
Heat Energy
Phase Change Movie Clip Yahoo! Video
What is a
heating
curve?
A graph that shows how
the physical state &
temperature of a substance
is affected by the addition
of heat over time
Physical State of the Water
1.
2.
3.
4.
5.
6.
7.
8.
9.
Between Points A & B___________________
Solid
Solid
At Point B_____________________________
Between Points B & C___________________
Solid & Liquid
At Point C____________________________
Liquid
Between Points C & D__________________
Liquid
Liquid
At Point D____________________________
Between Points D & E___________________
Liquid & Gas
At Point E_____________________________
Gas
Between Points E & F___________________
Gas
Date: 12/3/2007
Monday
Aim: 1. What are differences between
insulators & conductors of heat?
2. What are 3 methods of heat transfer?
Do Now: 1. Take out handout & note-packet
2. How does an ice cube form?
Homework: Read pgs 266-270 & answer self-check
questions (1-5) on pg 270
Type of phases change
Freezing(liquid to solid)
Melting(solid to liquid)
Vaporization(liquid to
gas)
Evaporation(liquid to
gas)
Sublimation(solid to
gas)
Condensation(gas to
liquid)
Deposition(gas to solid)
Heat change
Heat removed
Heat added
Heat added
Heat added
Heat added
Heat removed
Heat removed
Energy Changes
1. Every Diagonal
Temperature
changes as heat
energy is added or
removed
2. Every Plateau
(Phase Change)
Temperature stays
the same as heat
energy is added or
removed
• Substances that don’t
What are
insulators of conduct heat easily
heat?
• Examples: Glass, Wood,
plastic, rubber
What are
• Substances through which
conductors of
heat transfers easily
heat?
• Examples: Copper, Silver,
Iron, Aluminum
What are 3
methods of
heat transfer?
1) Conduction
2) Convection
3) Radiation
What are 3
1) Conduction:
methods of
• Heat transfer occurs by
heat transfer?
collision of particles
(direct contact)
• From warmer particles to
cooler particles
What are 3
2) Convection:
methods of
• Heat transfer through
heat transfer?
Liquids & Gases through
convection currents
• Ex. creates winds &
occurs in the mantle of
the earth
(Its less dense)
Cool air sinks
(Its more dense)
Convection Current
molecules move
faster & spread
apart becoming
less dense anything
less dense rises
molecules move
slower & closer
together becoming
more dense, anything
more dense sinks
What are 3
methods of
heat transfer?
3) Radiation:
• Heat transfer by infrared
waves through empty
space (a vacuum)
• Ex) The sun radiates
heat
Date: 12/4/2007
Tuesday
Aim: Lab: What are examples of conduction
& convection?
Do Now: 1. Take out homework.
2. Brainpop: States of Matter
Homework: Study for Quiz on Heat
Date: 12/5/2007
Wednesday
Aim: 1. Take & Go over Quiz
2. Review: What do you know about
Energy & Heat?
Do Now: Prepare for Quiz.
Homework: Bring a Pencil & Study for Exam on
Energy & Heat (Part II)
Name___________
Quiz
1. Heat never flows from areas of ___________ to
___________. (Hot to Cold, or Cold to Hot)
2. ___________have particles that are close together
& move the slowest. (Solids, Liquids or Gases)
3. ___________Phase changes are (chemical/physical)
changes of matter from one state to another.
4. ___________is the transfer of heat energy by
molecular (or direct) contact. (Conduction or
Induction)
5. ___________The condensing point of a substance
is equal to the __________ point. (Boiling point or
Freezing point)
6. ___________ is the measure of the average
kinetic energy of a substance. (Heat or
Temperature)
7. ___________During condensation (gas to
liquid) is energy absorbed or released?
8. ___________A phase change directly from a
solid to a gas is known as ____________.
(Melting, Condensation, Sublimation, or
Deposition)
9. ___________When a substance is heated,
its molecules vibrate (move):
A) Slower & closer together
B) Slower & farther apart
C) Faster & farther apart
D) Faster & closer together
10. ___________These pictures demonstrate
a process of heat transfer known
as________. (Conduction, Convection, or
Radiation)
Date: 12/6/2007
Thursday
Aim: Exam: What do you know about
Energy & Heat? (Part (II)
Do Now: Take out pencil, put up binders &
Prepare for Exam.
Homework: Bring a Pencil & Study for Exam on
Energy & Heat (Part I)
Date: 12/7/2007
Friday
Aim: Exam: What do you know about
Energy & Heat? (Part (I)
Do Now: Take out pencil, put up binders &
Prepare for Exam.
Homework: Have a good weekend!!!
Name___________
Quiz
1. ___________ is the energy trapped within
the bonds that hold atoms together.
2. ___________ is the most concentrated form
of energy.
3. ___________ are units used for energy.
4. ___________is energy associated with
moving charges (electrons).
5. ___________is the ability to do work.
6. ___________ is the type of energy associated
with the internal motion of molecules.
7. ___________is energy of position.
8. Potential Energy depends upon the
weight X _________ of an object.
9. The Law of ___________ of __________
states that energy can’t be created or
destroyed by ordinary means it can only
change from one form to another.
Answer questions 10-12 with the letter(s)
in the diagram to the left.
10. Where is P.E.
the greatest?
11. Where is K.E.
the greatest?
12. Where does
K.E. = P.E.?