Transcript Chapter 15 - MASHChemistry

1.
What is Energy?
It is the ability to do
work.
It is transferred by a
force moving an
object through a
distance.
2. What are the two
general types of
energy?
Kinetic Energy
Potential Energy
A1. What is Kinetic
Energy?
The energy of motion
Comes from the Greek
word kinetos,
“moving”
A2. What does Kinetic
energy depend
upon?
Mass and speed
A3. What is the formula
for Kinetic Energy?
KE = ½ mv2
Name
Symbol
Units
Equation
Kinetic Energy
KE
Joules (j)
KE = ½ mv2
Mass
M
Kilograms (kg)
M = 2KE / v2
Velocity
V
Meters/sec (m/s)
V = √ (2KE / m)
A4. Math Skills on Page 448
A 0.10-kilogram bird is flying at a constant
speed of 8.0 m/s. What is the bird’s
kinetic energy?
List, show formula, sub, math, answer!
Math Practice on page 448
1. 140 joules
2. 440,000 joules
3. 27 m/s
B1 What is Potential
Energy?
It is energy that is
stored as a result of
position or shape.
Potential Energy is
converted into
Kinetic Energy!
B2 What are two forms
of potential energy?
Gravitational potential
energy
Elastic potential energy
B3 What are some
examples?
Plucking a string and
lifting a book
B4. What is gravitational B5. What is elastic
potential energy?
potential energy?
Potential energy that
depends upon an
object’s height
Potential energy of an
object that is stretched
or compressed
Higher the height,
greater the PE
Greater the stretched or
compressed, greater
the PE
B6. What is the formula
for gravitational
potential energy?
PE = m x g x h
Name
Symbol
Units
Equation
Gravitational
Potential Energy
PE
Joules (j)
PE = m x g x h
Mass
M
Kilograms (kg)
M = PE / g x h
Gravity
G
Meters/second2
(m/s2)
G = PE / m x h
Height
H
Meters (m)
H = PE / m x g
Suppose the diver at the top of a 10.0
meter-high diving platform has a mass of
50.0 kilograms. What is her potential
energy?
A pear is 3.5 meters above the ground and
has a mass of .14 kg. What is the pear’s
potential energy?
C1. What are the final
two forms of
potential energy?
Chemical Energy
It is the energy stored
in chemical bonds.
When bonds are
broken , the
released energy can
do work.
Nuclear Energy
It is the energy stored in
atomic nuclei
It involves two forces,
strong and weak.
What are the different
forms of Kinetic
energy?
Light (EMR)
Electricity
Sound (Mechanical)
Wind (Mechanical)
Thermal (Heat)
Mechanical Energy
The energy associated
with the motion and
position of everyday
objects.
Speeding trains,
bouncing balls, wind,
and sound
Thermal Energy
It is the energy needed
to make the atoms
move faster.
Electrical Energy
Electromagnetic Energy
It is the energy
associated with
electric charges.
It is a form of energy that
travels through space
in the form of waves
Batteries
Lightning bolts
Ultraviolet
Roy G Biv
1.
What is energy
conversion?
Energy can be
converted from one
form to another.
2. What are the
different conversions
for lighting a match?
3. What is the law of conservation of energy?
Energy cannot be created or destroyed.
Energy can be converted from one form to
another.
4. What is the most
common energy
conversion?
The gravitational
potential energy of an
object is converted to
the kinetic energy of
motion as the object
falls.
5. What is a pendulum?
It consists of a weight swinging back and forth
from a rope or string.
Kinetic energy and potential energy undergo
constant conversion as a pendulum swings.
6. How do we find the total amount of energy
(Mechanical Energy)?
ME = KE + PE
ME = ½ mv2 + mgh
7. Math Skills on page 458
List, formula, sub, work, answer
Add on question: How high is the rock?
8. Math Practice on Page 458
9. What is the
relationship between
Energy and Mass?
Energy and mass are
equivalent and can be
converted into each
other.
10. What is the formula
for this relationship?
E = mc2
Albert Einstein
Special theory of
relativity in 1905
Name
Symbol
Unit
Equation
Energy
E
Joules
E = mc2
Mass
M
Kilograms
M = E / c2
Speed of light
C
Meters/second
C = √ (E / m)
11. How much energy does 1 gram of mass
have when converted to energy?
C = 3.0 x 108 m/s
List, formula, sub, answer
Answer = 9 x 1013 joules
1.
What are the two
types of energy
resources?
Nonrenewable and
renewable
2. What are
nonrenewable energy
resources?
They exist in limited
quantities and, once
used, cannot be
replaced except over
the course millions of
years.
Resources are oil,
natural gas, coal, and
uranium.
3. What are renewable
energy resources?
They are resources that
can be replaced in a
relatively short period of
time.
Resources are
hydroelectric, solar,
geothermal, wind,
biomass, and possibly in
the future, nuclear fusion
Hydroelectric Energy  energy obtained
from flowing water.
Solar Energy  sunlight that is converted
into usable energy.
Geothermal Energy  thermal energy
beneath Earth’s surface.
Biomass Energy  the chemical energy
stored in living things
Hydrogen Fuel cell  generates electricity
by reacting hydrogen with oxygen.
4. What is energy conservation?
Energy resources can be conserved by
reducing energy needs and by increasing
the efficiency of energy use.