Transcript Notes: Energy

Quick Write
•What is energy?
•What are the different
types of Energy?
Notes:
Energy
• Energy is the ability to work.
•Work is done when a force
exerted on an object moves
that object some distance.
•Work is a transfer of energy
Both work and energy are
measured in Joules.
Work & energy is force times distance
Units are: Newtons x meters
or
Joules
Two Types of Energy
• Kinetic Energy
• Energy
associated with
motion
• Ex. Dropping
the bowling
ball.
• Potential
Energy
• Stored energy
• Ex. Lifting a
bowling ball to
a height.
Kinetic Energy= 1/2mass X velocity squared
KE = ½m x v²
KE = (½ 3600Kg) X (10m/s)²
If the truck has a
mass of 3,600Kg
and a velocity of
10m/s, what’s it’s
Kinetic energy?
= 180000J
Kinetic energy
depends on the square
velocity! So at twice
the speed the truck has
4 x the energy
A more massive
truck has more
kinetic energy.
Equation for Gravitational
Potential energy
• PEgrav = mass x gravity x height
or
• PEgrav = m x g x h
Another type of Potential Energy
• Elastic PE
• PE associated with
objects that can be
stretched or
compressed.
Elastic Potential Energy
Gravitational
Potential
Energy
50Kg
10 meters
high
PEgrav = mass x gravity x height
PEgrav = 50Kg x 9.8m/s/s x 10m =
4900J
Please select a Team.
1.
2.
3.
4.
5.
6.
7.
8.
Team 1
Team 2
Team 3
Team 4
Team 5
Team 6
Team 7
Team 8
0%
0%
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0%
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8
If the mass of an object is 6g and
the density is 3g/mL, what is the
volume? Density = mass/volume
34
1.
2.
3.
4.
0
2mL
2g
18mL
18g
0%
1
0%
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4
What, if any, is the difference
in density between a 20g piece
of gold and a 600g piece of
gold?
34
1. 600g is greater in
density
2. No difference
0
0%
1
0%
2
What forces are acting on the
balloon?
34
1.
2.
3.
4.
0
Friction only
Gravity only
Elastic only
All of the above
0%
1
0%
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0%
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0%
4
When the motion of an object
changes, what has most likely
happened?
34
1. Forces are balanced
2. Forces are
unbalanced
0
0%
1
0%
2
Team Scores
4
Team 3
4
3.25
3
3
Team 4
Team 7
Team 1
Team 2
Channel Setting Instructions for ResponseCard RF
1. Press and release the "GO" or "CH" button.
2. While the light is flashing red and green, enter the 2 digit
channel code (i.e. channel 1 = 01, channel 21 = 21).
Channel is 41
3. After the second digit is entered, Press and release the
"GO" or "CH" button. The light should flash green to
confirm.
4. Press and release the "1/A" button. The light should flash
amber to confirm.
50Kg
Now calculate
Kinetic Energy
What’s its
velocity if-Just
it Add Water Lab
falls for one
second?
Kinetic Energy = ½m x v²
KE = (½ 50Kg) X (9.8m/s)²
= 2401 J
Thermal Energy
Temperature
• The measure of the particle
movement or kinetic energy of
atoms and molecules in an
object.
Absolute zero
• The lowest temperature
possible (-273 °C) when no
more energy can be removed
from matter, or when particles
are no longer moving.
Thermal Energy
•The total energy of
all particles in
matter.
Heat
•Movement of thermal
energy from a high
temperature to a low
temperature.
Heat Transfer
•Conduction: Heat is
transferred from one
object’s particles to
another
Heat Transfer cont…
• Convection: The mass
movement of heated
liquid or gas.
• EX. Wind, oven, home
heating system.
Radiation
• Transfer of energy
through electromagnetic
waves.
• EX: The sun
Conductors and Insulators
• A material that absorbs or conducts
heat well is a conductor.
• EX: Metals
Conductors and Insulators
• Insulators are materials that
do not conduct heat well and
slow the transfer of energy.
• EX: Wood, wool, straw,
Styrofoam
Specific Heat
• The amount of energy required to
raise the temperature of 1Kg of a
substance by one Kelvin.
• EX: water has a specific heat of
4.18J/KgxKelvin
• Units: J/KgxKelvin
Equation for change in Energy or
transfer of thermal energy
•Mass x specific heat x
change in temperature
Heat added = specific heat x mass x (tfinal - tinitial)
• Energy conversion – a
change from one form of
energy to another form.
Energy conversion cont…
• Most forms of energy can be
converted into other forms
• Example: Mechanical energy
(running water) can be converted
into electrical energy (electricity)
For example burning coal at an electrical
power plant converts chemical energy
into heat. The heat makes steam
turns
Gaswhich
 engine
turbines mechanical energy to make
electrical energy. The electrical
energy
photosynthesis
is converted back into heat (oven), light
(lights in the house), and
Food  your body
mechanical energy (a car’s engine)
when it is used.
Heat lamp or hair
dryer
Oil  electricity via
power plant
Conservation of Energy
• Law of Conservation of Energy:
when one form of energy is
converted into another form of
energy, no energy is destroyed in
the process
• Energy can not be created or
destroyed
Different Forms of Energy
• Mechanical = motion or position of
an object
• Thermal = total energy of the
particles in an object (the more
energy the more heat is given off)
• Chemical = PE stored in chemical
bonds (food)
• Electrical = energy caused
by moving electric charges
• Electromagnetic energy =
visible light, microwaves,
x-rays, and uv light
• Nuclear = fission and
fusion
Power
• Power is the amount of work
done in a given time.
Equation for power
Power = work/time
or
Power= force x
distance/time
Power cont…..
• Units for Power
Joules/second or…
Watt (w)
Formation of fossil fuels
• In the earth’s crust, under
distinct pressure,
temperature and geological
processes, nonrenewable
energy formed from once
living organisms.
Common Types of
Fossil Fuels
•Coal
•Oil (petroleum)
•Natural Gas
• Fossil Fuels make good fuels because the energy stored
in them is abundant and easy to release when heated.
•
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Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Pentadecane
jet fuel)
• Tetracosane
oil)
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C15H32
(gas)
(gas)
(gas)
(gas)
(liquid, found in gasoline)
(liquid, found in gasoline)
(liquid, found in gasoline)
(liquid, found in gasoline)
(liquid, found in kerosene and
C24H50
(liquid, found in lubricating
Some common uses of Crude Oil
•
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•
•
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•
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Solvents
•Kerosene
Fertilizers
•Synthetic fibers
Pesticides
•Synthetic rubber
Plastics
•Detergents
Diesel fuel
Jet fuel
liquified petroleum gas
plastics
Source: Energy Information Administration