Download Thermal Energy

Thermal Energy
Temperature
• What’s today’s temperature outside?
• Depending on the weather, we wear different
clothing and accessories. For example, when
it’s cold, we wear?
• But, does “hot” mean the same thing to you
as it does to me? What about “cold”?
What is temperature?
• In order to define temperature we need to do
a quick review of atoms!
• Atoms: the smallest particles that make up all
matter.
• Matter: everything around us (has mass and
takes up space)
• Solid, Liquid, & Gas: atoms move differently in
each of these
• Kinetic energy: energy that moves!
Temperature & Kinetic Energy
• Note: Temperature – is a measure of the
average kinetic energy of particles in an
object.
• Let’s make the connection: The higher the
temperature of an object, the more it’s atoms
and molecules have more _______ energy.
Measuring Temperature
• Celsius- scale was devised by dividing the range of
temperature between the freezing and boiling
temperatures of pure water at standard atmospheric
condition into 100 equal parts: freezing point of water is 0
C and boiling point is 100 C; bigger than F
• Kelvin- temperature scale is an extension of the degree
Celsius scale down to absolute zero
• Fahrenheit- non-metric temperature scale was devised and
evolved over time so that the freezing and boiling
temperatures of water are whole numbers, but not round
numbers as in the Celsius temperature scale; freezing point
of water 32 F and boiling point is 212 F (divided into 180
degrees) – used mainly in the US.
Converting
• From F to C: 5/9 x (F – 32)
• From C to F: (9/5 x C) + 32
• From C to K: C + 273
Just Thermal!
• Thermal energy:
– Particles in matter are moving
– They have energy because they are moving
– Continual motion = Thermal energy
– Can be transferred (all energy can)
Thermal in Action
Thermal Energy & Heat
• Thermal Energy happens when? Let’s Review
• We also know that thermal energy (all energy)
can be transferred.
• Let’s think about a cold glass of tea. It’s colder
than my hand that’s holding it. The heat from my
hand transfer to the glass…and the glass warms
up.
• Note: Heat – is the transfer of thermal energy
from a substance at a higher temperature to a
substance at a lower temperature.
Thermal Energy & Heat Continued
• Note: Thermal energy moves from warmer
objects to cooler ones.
• Note: Water is unusual because it takes a large
amount of thermal energy to raise its
temperature; water’s temperature doesn’t
change as much as surrounding air or land.
• Note: Thermal energy can be transferred in 3
ways: Conduction, Convection & Radiation
Conduction
• Have you ever picked up a metal spoon from a boiling
pot? How does it feel?
• HOT!!!! But, how did it get so hot and why?
• The answer is Conduction!
• Note: Conduction - is the transfer of thermal energy
by collisions between atoms; usually occurs in solids
• As part of spoon in the boiling water becomes warmer,
the atoms and molecules move faster….increasing it’s
temperature. These particles hit (collide) with the
slower particles in the spoon, and the thermal energy
is transferred.
Conduction - Visual
Conduction in Action
• Conduction
Good Conductor & Insulators
• Thermal energy moves differently depending on the
materials it’s moving to.
• Good conductors – are materials in which thermal
energy can transfer easily
• What are some good conductors that you know of?
• - Metals (are the most popular)
• Insulators are different. These materials are NOT good
conductors, so they are used as thermal insulators.
• Insulators keep the heat in. (Ex. Sweaters, blankets,
thermal underwear)
Convection
• Thermal energy can also be transferred by
particles that move from one place to another.
• Note: Convection – transfers thermal energy
when particles move between objects or areas
that have different temperature.
Convection 101
Convection in Weather
Convection - Visual
Radiation
• Background: Comes from Radient Energy (sunlight)
• Radiation: Thermal energy that is transferred by
waves.
• These waves can be visible (light waves) or invisible.
• The sun transfers energy to the Earth via radiation.
• When you stand by a fire the radiation of heat makes
you feel warm.
• A microwave cooks your food using microwave
radiation to transfer energy to your food.
Radiation
Radiation – Visual
We use all 3!