Download File - Mrs. burt`s physical science class

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Unit 6
• Lesson 11 Thermal Energy
• Lesson 12 Temperature
• Lesson 13 (Optional)
Mission
The mission of the Michigan Virtual Charter
Academy is to provide an innovative, intensive
academic preparation that inspires and educates
students to achieve the highest levels of academic
knowledge and skills. Michigan Virtual Charter
Academy embraces a collaborative partnership
between teachers and parents in order to empower
student
to
reach
extraordinary
heights.
Extraordinary results require extraordinary efforts!
Through commitment, hard work. Consistency, and
responsibility, every students will meet the
challenge of mastering high expectations.
Vision
The vision of Michigan Virtual
Charter Academy is to lift students
up in a safe, student-centered
environment to become confident
leaders of the digital age.
Agenda
• House keeping
• Thermal Energy
– Conduction
– Convection
– Radiation
• Temperature
– Temperature vs. Thermal energy
– Expansion and Contraction
– Thermometers
• Fahrenheit, Celsius, Kelvin
• Converting
• Exit ticket
House keeping
• Office Hours
– Mrs. Schneider’s Tuesday 2-3pm
– Mrs. Burt’s Wednesday 2-3pm
• You can attend either office hours, but only
Kmail your teacher with questions.
• Remember to be positive!
Lesson 11 Objectives
Thermal Energy
1. Compare and contrast the transfer of thermal
energy through radiation, convection, or
conduction.
2. Recognize that changes in the temperature of
an object will affect the kinetic energy of that
object.
3. Describe how thermal energy flows from a
system of higher temperature to a system of
lower temperature.
Why does an popsicle melt on a warm
tongue?
• There is a temperature difference between
the tongue and the popsicle, so heat energy
flows from the warm tongue into the cold
popsicle.
• This means that the popsicle melts as it gets
warmer.
Review
• Kinetic energy is the energy of motion
• Potential energy is the stored energy of position.
New
• Thermal energy is the total energy of an object.
That is the total of the kinetic and potential
energy
Thermal Energy depends on the size of
the object.
Which block has more atoms?
Which block has more energy?
Which block has more thermal energy?
Thermal energy depends on
temperature of the object.
Which block has
more kinetic Energy?
Which block’s atoms
are moving faster?
Which block as more
thermal energy?
Thermal energy is the total of all the
internal energy in an object.
Heat
Cup gets cooler while
hand gets warmer
The flow of
thermal energy
from one object to
another.
Heat always flows
from warmer to
cooler objects.
Ice gets warmer
while hand gets
cooler
Heat transfer is a flow of energy between two
objects due to a temperature difference
between the objects.
–Heat transfer is the way in which
thermal energy is moved from a hot
object to a colder object.
Hot water
(90. oC)
Cold water
(10. oC)
Water
(50. oC)
Water
(50. oC)
What is thermal equilibrium?
• Thermal equilibrium – when the atoms of
both blocks are moving the same amount or
have the same temperature.
Thermal Equilibrium
Thermal Equilibrium

When hot water and ice
are placed in a closed
system:
1. The energy lost by the
hot water is equal to
2. The energy gained by
the ice.
3. Eventually, the
contents reach thermal
equilibrium.
What is Heat?
• Heat is the movement of thermal energy, or
the transfer of thermal energy, from one
substance to another;
• Why does a chocolate bar melt when you hold
it in your hand?
Why does a chocolate bar melt when
you hold it in your hand?
• Heat is transferred from warmer to cooler
objects
• Remember: Objects do not contain heat.
Instead they contain thermal energy. Heat is
just the transfer of that thermal energy.
Heat is transferred in three ways
Heat is the transition of thermal energy
from a hotter to a cooler body
• Radiation
• Conduction
• Convection
What is conduction?
How are the particles arranged in a solid, a liquid and a gas?
solid
liquid
gas
Particles that are very close together can transfer heat
energy as they vibrate. This type of heat transfer is called
conduction.
CONDUCTION . . . . . . . . .
. . . . . . heat transferred through a substance or from one
substance to another by direct contact of molecules.
CONDUCTION can take place in solids, gases, and liquids,
but takes place BEST in solids, because the molecules of a
solid are in direct contact with one another.
Which picture is showing conduction?
Convection
• Convection is the
transfer of heat by the
actual motion of a fluid
(liquid or gas) in the
form of currents.
• Convection comes from
a Latin word meaning
"to carry together."
CONVECTION . . . . . . . . . .
. . . . . . . . . heat energy transferred through liquids and gases by
means of up-and-down movements called convection currents.
WHEN A LIQUID is heated, the molecules begin to move faster.
The hot water at the bottom of the pot
rises to the top of the pot, and is
replaced by the cooler water.
Next the cooler water is heated.
Boiling water
Weather patterns and their movement are dependent
on convection currents . . . . .
Does your refrigerator use convection?
RADIATION heat energy transferred through space.
Heat from the sun reaches the Earth by means of
RADIATION . . . . . . ( 8 minutes at 186,000 miles per second).
fireplace . . .
Heat lamp . . .
Land heats up and cools down faster than water
Lesson 12 Objectives
Temperature
1. Explain that changes in the position and motion
of atoms in a solid, liquid, or gas are the result of
temperature increase or decrease.
2. Explain how the kinetic energy of atoms or
molecules of different objects varies with their
temperature.
3. Describe the differences between thermal
energy, kinetic energy, potential energy, and
temperature.
Temperature

Temperature is a measure of average kinetic
energy of the molecules of an object.
As temperature
increases, so does the
average kinetic energy
of the molecules.
Examples
Why does this
help to get the
lid off?
The temperature
of the metal
increase,
it expands.
LIQUIDS . . . . . . .
Most liquids expand when they are heated.
Exception: water expands as it cools. As the volume
increases, the density decreases.
Temperature
• The higher the average KE, the higher the temperature
• Which substance has a lower temperature?
When the temperature increases the particles move faster.
Temperature and Thermal Energy
What’s the difference?
• Temperature IS NOT HOW HOT OR COLD
SOMETHING IS!
• Temperature is defined as the measure of the
average kinetic energy of the individual
particles in an object.
• Thermal energy is defined as the total energy
of all the particles in an object.
Thermal Energy VS. Temperature
TEMPERATURE IS a measure of the average
kinetic energy of the molecules in a
substance.
Thermal energy is defined as the total energy of
all the particles in a substance
Adding thermal energy to a substance increases
the average kinetic energy of the molecules
and therefore causes a rise in temperature.
Higher temperature = faster molecular motion
Lower temperature = slower molecular motion
If these two blocks are the same
temperature that would mean what?
They have the same average kinetic
energy of their atoms.
A THERMOMETER IS AN instrument used for measuring
temperature and works because of thermal expansion . . . . . . .
As the liquid (usually alcohol) in a thermometer gets warmer, it
expands and rises in the tube. The opposite happens as the
liquid gets cooler.
Fahrenheit and Celsius
• People around the world measure
temperature with different scales.
• Two common scales are Fahrenheit and
Celsius.
• Let’s compare them by considering the
freezing and boiling points of water.
CELSIUS
FAHRENHEIT
100 degrees
boiling
point
(water)
212 degrees
37 degrees
human
body
temp
98.6 degrees
20 degrees
Comfortable
room temp.
68 degrees
0 degrees
freezing
point
(water)
32 degrees
Converting Fahrenheit and Celsius
• To convert Fahrenheit to Celsius: °C = (5/9) (°F – 32)
• To convert Celsius to Fahrenheit: °F = (9/5) (°C) + 32
•
•
•
•
•
•
•
Notice the difference! Order matters!
Change 20°C to Fahrenheit
°F = (9/5) (20°C) + 32
°F = (1.8) (20°C) + 32
°F = (36) + 32
°F = 68
20°C = 68°F
SCIENTISTS SOMETIMES USE another metric temperature
scale  the KELVIN SCALE.
The LOWEST temperature than can be reached ( a point in
which all molecular motion stops ), is called ABSOLUTE ZERO
or 0 K.
You can CONVERT Celsius degrees to Kelvins (K) simply by
ADDING 273 to the Celsius temperature.
0 ºC = 273 K
100 ºC = 373 K
0 K = -273 ºC
Celsius (C)
0
0
212
Matching…
a.
1.
2.
3.
4.
5.
6.
Farenheit Scale
Celsius Scale
Kelvin Scale
Absolute Zero
Thermal Energy
Temperature
b.
c.
d.
e.
f.
the temperature scale used in most of
the world
The total energy of all particles in a
substance
The temperature at which no more
energy can be removed from an object
A temperature scale in which the interval
between the freezing point and boiling
point of water is divided into 180 equal
parts
A measure of average kinetic energy of
the individual particles in an object
A temperature scale with no negative
numbers
Matching…
a.
1.
2.
3.
4.
5.
6.
Farenheit Scale
Celsius Scale
Kelvin Scale
Absolute Zero
Thermal Energy
Temperature
b.
c.
d.
e.
f.
the temperature scale used in most of
the world
The total energy of all particles in a
substance
The temperature at which no more
energy can be removed from an object
A temperature scale in which the interval
between the freezing point and boiling
point of water is divided into 180 equal
parts
A measure of average kinetic energy of
the individual particles in an object
A temperature scale with no negative
numbers
Exit ticket
• Fill out the following Exit ticket.
• https://docs.google.com/forms/d/19BWiIhjtCxcYcCnZKkBd5WSJruWUCnsNEIWjaeHH1Q/vi
ewform
• If you have question, come to office hours!