Transcript File - OCMS Science

Heat Transfer
Energy transformations
Heat
When atoms/molecules move, they transfer
thermal energy creating heat.
Key words/connections
• The faster they move = more heat produced
• Heat and its transfer is important for creating
Earth processes like weather, ocean currents,
and climate
Temperature
• The measurement of how fast
the molecules inside an object
are moving.
Key words/connections
Fast moving molecules = high temperature
Slow moving molecules = low temperature
Heat Transfer
When heat energy moves between two objects of
different temperatures. Heat energy moves from
the object with more heat to one with less
Key words/Connections
Energy cannot be created or destroyed! It
just moves to another object!
Thermal Equilibrium
• The transfer of heat energy from hotter
objects to colder objects until both are the
same temperature (equal).
I got to work and poured myself a cup of hot coffee. I
then got called to a meeting. I was gone for over an
hour. When I came back my coffee was now cold.
Can you explain what has
happened?
What is the temperature in
degrees Celsius?
Each centigrade (notch/line) is
worth how many degrees
celsius?
Thermal equilibrium lab
• Hot beaker
• Cold beaker
• Measuring temp and taking observations
Eureka video: Conduction
• http://www.youtube.com/watch?v=wV7gzcKe
gdU
• Conduction heat energy that must be
transferred directly from one object to
another through direct contact. (touching)
Heat can be transferred from one
object to another, or from one
molecule to another through the
process of conduction. As one
molecule is heated it begins to move
and shake rapidly. As it does so, it
passes some of its heat energy to
other molecules around it. Through
this process, all the molecules of an
object pass heat from one to another,
until they are all hot
Where do you see conduction?
Where do you see conduction?
Where do you see conduction?
Where do you see conduction?
Where do you see conduction?
• Why do people use the phrase “heat rises”?
Where does this phrase come from? (which
method of heat transfer does it relate to?
Exit Slip
Welcome to Class
1. Agenda’s
2. Get out your guided notes packet that we
were working on and a pencil!
Eureka- convection
• http://www.youtube.com/watch?v=ON2Y3FEk
_UI
• Convection Heat that is transferred through
a liquid or a gas that causes it to rise and fall in
something called a convection current.
Convection Current
• As a gas or a liquid is heated, it warms, expands, and rises
because it is less dense (lighter). When the gas or liquid cools,
it become heavy (more dense) and falls. As the gas or liquid
warms and rises and then cools and falls it creates a
convection current. Convection is the primary method heat
moves through a liquid or gas.
Convection Current
• As a gas or a _______is heated, it warms, expands (spreads
out), and ___________because it is less ___________. When
the gas or liquid cools, its molecules come closer together and
become more ____________making them_________. As the
gas or liquid warms and rises and then cools and falls it
creates a convection____________. Convection is the primary
method heat moves through a _____________ or _________.
Convection Currents
The wind we feel outside is often
the result of convection currents.
You can understand this by the
winds you feel near an ocean.
Warm air is lighter than cold air and
so it rises. During the daytime, cool
air over water moves to replace the
air rising up as the land warms the
air over it. During the nighttime, the
directions change -- the surface of
the water is sometimes warmer and
the land is cooler.
Convection currents
• Convection is the movement of gases or liquids from a warmer spot to a
cooler spot. If a soup pan is made of glass, we could see the movement of
convection currents in the pan. The warmer soup moves up from the
heated area at the bottom of the pan to the top where it is cooler. The
cooler soup then moves to take the warmer soup's place. The movement
is in a circular pattern within the pan
Where do you see convection?
Where do you see convection?
Convections Currents
Where do you see convection?
Where do you see convection?
Where do you see convection?
Where do you see convection?
• Writing Prompt
How do we feel the heat from the sun?
How does it transfer its heat to us?
• Radiation: heat that is transferred through
empty space in the form of rays or waves.
• Radiation is the final form of
movement of heat energy. The
sun's light and heat cannot reach
us by conduction or convection
because space is almost
completely empty. There is
nothing to transfer the energy
from the sun to the earth.
• The sun's rays travel in waves
called heat rays. When it moves
that way, it is called radiation.
The Sun's Radiation
• The sun emits many kinds of radiation. Heat is only a
part of what it emits.
• The sun also emits light, radio waves, gamma
radiation, ultraviolet and infrared radiation.
• All these forms of radiation together are called the
Solar Wind.
http://www.youtube.com/watch?v=2JZciWtK6vc
• Radiation: Electromagnetic waves that directly transport
ENERGY through space. Sunlight is a form of radiation that is
radiated through space to our planet without the aid of fluids
or solids. The energy travels through nothingness! Just think
of it! The sun transfers heat through 93 million miles of space.
Because there are no solids (like a huge spoon) touching the
sun and our planet, conduction is not responsible for bringing
heat to Earth. Since there are no fluids (like air and water) in
space, convection is not responsible for transferring the heat.
Thus, radiation brings heat to our planet.
Microwaves
• Microwave radiation refers to the radiating wave
movement in which microwave energy travels.
• Microwaves take a straight line path. Like all
electromagnetic waves, they do not require a
medium to travel through. They can pass through
non-metal materials like plastic and glass, but get
reflected off metal surfaces.
Where do you see radiation?
Where do you see radiation?
Where do you see radiation?
Set your paper up like this
Procedure
•
•
•
room temperature water
ice water
hot water
1. Cold water = blue
hot water = red
2. Use a dropper to drop the
cold water into the room temp
water
3. Use a dropper to then drop
the hot water into the room
temp water.
Observation
What form of heat
transfer? Why?
Set your paper up like this
Procedure
Observation
Draw what you observed
happening
What form of heat
transfer? Why?
Set your paper up like this
Procedure
Observation
What form of heat
transfer? Why?
This demonstration shows
me how heat is transferred
through a liquid so it shows
me CONVECTION.
I observed hot water rising
and cool water sinking. This
shows me that when liquids
gain heat energy they
become less dense and rise
and when liquids have little
heat energy they become
more dense and fall.
This is what creates
convection currents.