Wt=50N
1. What is the KE at point A? Why?2. What is the PE at point A?3. What is the ME at point A?4. What is the height at point B?5. What is the height at point C?
A.
B.C.
WARM UP
Warm up…
1. What is heat?
2.How does thermal energy play a role in the Law of Conservation of Energy?
Bill Nye; HeatBEFORE: List the forms of energy that
you know and understand
DURING: Write notes about heat, conduction, convection, radiation
AFTER: Write a paragraph that describes thermal energy, heat, and the processes of conduction, convection, and radiation.
Roller Coaster Energy Problems
1. Find the PE at point A.2. Find the KE at point A.3. Find the ME at point A.4. Find the KE at point B.5. What is the ME at point C?6. Find the PE at point C.7. Find the KE at point C.
HT=250 mWT=200N
HT=20 mWT=200NM=20kg
V=200m/s
Answer the problems on the left on your sheet under the
roller coaster picture.
A.
B.C.
Warm up…
1. Describe the energy transfers that occur in a light bulb.
2. Describe the energy transfers that occur when the body is
powered by food.
Warm up…
1.Describe the energy transfers in a hairdryer.
2.What is the difference between renewable and
nonrenewable energy resources?
Types of EnergyForms Explanation Example
MechanicalTotal energy of
motion and position
ThermalTotal kinetic energy
of particles
ChemicalEnergy stored in
rearranging atoms
Types of EnergyElectrical
Energy of moving electrons
SoundEnergy of vibrating
particles
LightVibrations of electrically
charged particles
NuclearEnergy in the nucleus of
an atom
1. Mechanical Energytotal energy of motion and position
ME=KE + PE
An object on the top of a hill has high ____ energy and low ____ energy.
As the object rolls down, what happens?
Why does there seem to be less energy at the bottom of the hill than at the top?
2. Electrical Energythe energy of moving electrons
Like charges repel and
Opposite charges attract
++
+ -
Two Types of ElectricityStatic Electricity
Current Electricity
The Power of ElectricityCan be turned into other kinds of energyCan do work
Hairdryer converts electric to thermalAlarm clock converts electric to sound and
light
3. Nuclear Energy
Fission Fusion
the energy of the nucleus of an atom
Pros and Cons of Nuclear Energy
+ make electrical energy
+ no carbon dioxide or other gases
- limited fuel supply - radioactive waste
products- possible release of
radioactive material
+ fuel is plentiful+ only small amounts
of radioactive waste products
- not currently
practical - large amount of
energy needed to heat and contain the hydrogen plasma
Fission Fusion
The Sun
Giant nuclear fusion reactor
Ultimate source of energy for our planet
4. Chemical Energythe energy of rearranging atoms
Is photosynthesis endothermic or exothermic?
Is respiration endothermic or exothermic?
5. Sound Energy
-caused by vibrations & carried through a substance.
the energy of vibrating particles
Making Sound vs. Hearing Sound
Have you heard this riddle?
If a tree falls in the forest and no one is around to hear it, does the tree make a sound?
What do you think?
0
When a tree falls and hits the ground, the tree and the ground vibrate. These vibrations are
transferred to the surrounding air.
So there would be a sound!!!
0
Change Frequency = Change Pitch
TRY IT! – Vocal cordsWATCH IT! – Jars vs. Bottles
TRY IT!Hold the cut rubber band stretched tight.
Have a partner pluck the rubber band with their finger.
Notice the pitch.
Shorten the length of rubber band by holding it in the middle.
What was different??
Echolocation
6. Light Energythe vibrations of electrically charged particles
Called PHOTONS
The EM SpectrumVisible light is one portion of
the Electromagnetic Spectrum.
All of these waves are energy-filled waves.
Insects, like bees, see shorter wavelengths than humans. What type of EM waves do they see?
WATCH IT! - prism
Possibilities of LightLight rays move away from their source in straight lines.
When they hit something, they are either
Reflected(bounced off)
Refracted(bent)
Absorbed(stopped)
WATCH IT! - Mirror
TRY IT!Fill beaker half full of water. Put a pencil in the glass.Look at the pencil through the side of the
glass.How does the pencil look different than it did
before you put it in the water?This is an example of ______________.
TRY IT!Prop up the card with the arrow on it.
Place a glass of water a little to one side of the card and a few inches in front of it.
Now stoop down until your eyes are level with arrow.
Slide the glass between the card and your eyes. Try sliding it back and forth a few times.
What happened? What causes this?
Light Source or Not?You can see a light source even in the dark because its light passes directly into your eyes. Most things around you are not light sources. Why can you still see them?
You can still see them because light from light sources reflects off the objects and then travels to your eyes.
The Speed of LightWatch this clip to learn more about the speed of
light.
Check your Light Understanding
What is a photon?
On the EM spectrum, what type of EM radiation has the highest energy – radio waves, gamma rays, or x-rays?
What are 3 possible things that can happen to light rays after they leave the source?
Sound & Light: Alike, but Different
Sound*vibration*needs a medium
*longitudinal
Light
*does NOT need a
medium*transverse
Both
are
WAVES
7. Thermal Energy
more thermal energy = faster moving particles
less thermal energy = slower moving particles
the total kinetic energy of the particles
Thermal Energy vs. HeatHeat is the transfer of energy between objects that are at different temperatures.
Three Kinds of HeatConduction Convection
Radiation
(touch) (current) (rays)
Hot Cold
Common
Check your Thermal UnderstandingIs thermal energy kinetic or potential?
If you touch something in which the particles are moving faster than the particles in your skin, how would it feel?
When objects have more thermal energy than their surroundings, what do you predict will happen in terms of heat?