Transcript Energy
Energy
Chapter 14
Prior Knowledge
What is energy?
What are waves and where are they
found?
What are the parts of a wave?
What is light?
14-1
What Are Some Forms of Energy?
1. Energy= the ability to cause change in
matter.
2. Potential energy= energy that is due to
the position or condition of an object.
Example:
Skier at top of hill.
Yo Yo before it falls
Newton ball before it is let go.
Water at top of waterfall
Stretched rubber band
Drawing a bow and arrow
3. Kinetic energy = Energy of motion.
Examples: Skier moving down a hill
yo yo moving up and down.
Newton balls moving back and forth
Water flowing down a waterfall
Rubberband flying through the air
Arrow moving towards a target
Examples of Energy
Transformations
1. Fireworks:
-starts as stored chemical energy as a rocket
-moves to kinetic energy at the rocket moves into sky.
-Flash of light is chemical energy
- Sound (bang) is sound energy.
2. Battery:
-starts as chemical potential energy.
- When battery is being used it is electrical energy.
- Heat is produced so it is thermal energy.
-Light shown is light energy.
14-2 What are Waves?
1. Waves are a disturbance that carries
energy through matter or space.
2. Wavelength = distance from middle of
crest to middle of next crest on a wave.
3. Amplitude = distance from resting position
to either the top of crest or bottom of
trough
Sound waves
1.
2.
3.
A single sound wave is made up of one
compression area and one spread area.
Frequency = number of times the string
vibrates in a given amount of time.
(hertz)
Pitch: refers to how high or low sound is.
The higher the frequency or a wave the
higher the pitch.
4. Loudness is measured in decibels (dB).
-The larger the amplitude the louder
the sound.
- Loud sounds can cause pain and
hearing damage.
*wear ear protection to block
sounds above 80 dB.
(airplanes, rock concerts, factories.)
Light and
Electromagnetic Waves
1.
2.
Light is a form of energy that travels in
waves but doesn’t need matter.
Electromagnetic spectrum = all energy
waves that travel at the speed of light in
a vacuum.
-
-
radio, microwaves, infrared, visible, ultraviolet, xray, and gamma rays
Visible light is part of the spectrum that you can
see.
Light Energy from the Sun
-
-
Heat
Makes air flow
Water to evaporate (water cycle)
Produces food for plants, animals, humans
Photosynthesis
Carbon Dioxide
+
Light
Water >>>>>
Glucose +
Chlorophyll
Oxygen
14-3 How Does Light Behave?
1.
Reflection = The bouncing of light off a
surface.
- mirror or still water
- rough surfaces don’t reflect light they
absorb light.
2. Visible light is white.
- when white light passes through a prism, its
path changes, and white light is separated.
**Red Orange Yellow Green Blue Indigo Violet
Carrot
is orange because all other colors are
absorbed and orange is reflected.
Black objects absorb all wavelengths of light and
reflect very little light. This is why black top parking
lots are hot.
Refraction and Diffraction
3. Refraction = The bending of light as it
passes from one material to another.
Examples: pencil, straw, or flower in
glass of water.
(light leaves water
and enters air it
speeds up
and bends.)
4. Diffraction = The bending of light around
the edge of an object.
-Particles in the air cause diffraction in
the atmosphere.
-Longer wavelengths
(red) tend to diffract
more often.
5. Transparent = allowing almost all light to pass
through.
Example: colored glass, light covers
6. Translucent = allowing some light to pass
through.
Example: tissue paper, wax paper, some
plastic.
7. Opaque = don’t allow any light to pass through.
Example: metals, clay pots, soil, tree, house