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. A single sound wave is made up of one compression area and one spread area.

2. Frequency = number of times the string vibrates in a given amount of time. (hertz)

3. 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. Light is a form of energy that travels in waves but doesn’t need matter.

2. Electromagnetic spectrum = all energy waves that travel at the speed of light in a vacuum.

- radio, microwaves, infrared, visible, ultraviolet, x-ray, 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

LightCarbon Dioxide    +    Water    >>>>>      Glucose   +    Oxygen Chlorophyll

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 Diffraction3. 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