Transcript File - Mrs. Spock 8th Grade Science

Opening Assignment
What is the primary energy source
that drives all weather events, including
precipitation, hurricanes, and tornados?




A. the Sun
B. the Moon
C. Earth’s gravity
D. Earth’s rotation
How is heat transferred?
 Conduction!
 Convection!
 Radiation!
What is conduction?
Heat is transferred from one particle of
matter to another without the
movement of the matter.
 Hot atoms and molecules come in
contact with cool atoms and molecules
and heat is transferred!

http://tdflashzone.net23.net/index
.php?p=2_73
Slide 5
When do you experience heat
transfer by conduction
When you walk on a hot sidewalk or hot sand on the beach, the
sand warms—or burns—your feet through conduction. When a
warmer substance with quickly moving molecules (the sand)
comes into contact with a cooler substance with slowly moving
molecules (your bare feet), the faster molecules bump into the
slower ones and make them move faster, too.
Youtube video

Eureka! Episode conduction
What is convection?


Convection is heat transferred by movement of currents
in a liquid or a gas (like air).
Hot fluids (air or liquids) rise! Cold fluids sink!
Why do hot fluids rise? Why do
cool fluids sink
Density!!!
Heat caused the
molecules to move
faster and expand.
They become less
dense.
 The colder, more
dense fluid sinks


Youtube video
Convection Currents
 TeacherAJH
 Convection Currents - YouTube

Convection in the mantle
Heat transfer from the center of
Earth to the surface
Examples in real life

Why is upstairs in your house always
hotter than your basement?
Radiation!

Radiation is the
transfer of energy by
electromagnetic
waves.
– Sun
– Heat from a fire
– lamp
 Radiation does not
require matter to transfer
heat
The diagram below represents an experiment on different
types of soil.

The thermometers are measuring the temperature of the center of
the soil samples. The temperatures are different. Why

The thermometers are measuring
the temperature of the center of the
soil samples. Which of the following
is a cause of the measured
difference in the temperature of the
two soils?

A. conduction within different soil types
B. condensation within different soil types
C. radiation emitted by different soil types
D. convection in the air above different soil
types



MCAS Question
Heat from deep in Earth's interior is
transferred to its crust by which of
the following?





A. conduction in the ocean
B. convection in the mantle
C. radiation from the solid core
D. evaporation at mid-ocean ridges
Opening Assignment

You want to pour very hot coffee into a
cup so you can drink it after it cools
down…. Which cup is a better choice?
Why?
Conductors and Insulators
A conductor transfers thermal energy or
heat well. An insulator does not!
 Metals such as silver and stainless steel
are good conductors.


Insulators
A substance/material that heat or
electrical current cannot flow though well
Insulating window
Other insulators
List some other materials you know that are
good insulators.
Heat absorption

On a very hot day in the summer what
color shirt should you wear?
Answer
Black or dark colors absorb radiation from
the sun.
 White or shiny objects reflect the sun’s
radiation

Conductors

a conductor is a material conducts heat
well and electrical charges can easily flow
through.
The end.