Chapter 1 and 2 notes- SOUND
- A wave is disturbance that carries from one place to another.
- Mechanical waves require a medium. Electromagnetic a vacuum or through a medium.
- When a wave is graphed, the highest points are called a crest and the lowest points are called troughs.
- The maximum displacement of a wave is its amplitude.
- The distance between two consecutive similar points on a wave is a wavelength.
- The frequency of a wave is the number of waves that pass a point per unit of time.
- In a transverse wave, the motion of the medium is at the right angles of the direction of the motion of the waves.
- The motion of the medium is parallel to the direction of a longitudinal wave.
- The wave speed equals frequency times the wavelength.
- The density and elasticity of a medium affect the speed of CHAPTER 3 EARTH SCIENCE REVIEW
VOLCANOES AND PLATE TECTONICS
Volcanoes form at weak spots in the earth’s crust where magma comes to the surface.
- Magma: molten rocks, gases and water from the mantle
- Lava: magma reaching the surface
Volcanic activity is a constructive force…why?
IN YOUR OWN WORDS: Tell me in 2-3 sentences now…..:
Locations of volcanoes:
- 600 active volcanoes
- Many lie beneath the sea
- Occur in belts across continents and oceans
Pacific ocean has the “ ring of fire.”
Volcanoes occur from divergent plate boundaries and in subduction zones at convergent plate boundaries.
Divergent plate boundary volcanoes.
- Form along the mid-ocean ridge
- Lava pours out of cracks in the floor
Convergent plate boundary volcanoes:
- Subduction zones cause oceanic crust to sink into the mantle. Crust melts and forms magma which rises to the surface
- Where oceanic plates collide, the older plate goes under the newer, creating a trench. The trench melts and forms magma, eventually forming volcanoes
- Island arcs are formed this way
Hot spots are areas were magma melts through the crust like a blowtorch. Usually lie in the middle of an oceanic and continental plate.
VOCABULARY FOR THE CHAPTER:
Volcano- A weak spot in the crust where molten material or magma comes to the surface.
Magma- A molten mixture of rock forming substances, Gases, and water from the mantle.
Lava- When magma reaches the surface.
Ring of fire- One major volcanic belt.
Island arc- The resulting volcanoes that create a string of islands.
Hot spot- An area where magma from deep within the mantle melts through the crust like a blow torch.
Magma chamber- Beneath the volcano where magma collects in a pocket.
Pipe- a long tube in the ground that connects the magma chamber to the earth’s surface.
Vent- Molten rock and gas leave the volcano through a vent.
Lava flow- The area covered by lava as it pours out of a vent.
Crater- A bowl shaped area that may form at the top of a volcano around the volcanoes central vent.
Silica- A material that is formed from the elements oxygen and silicon is one of the most abundant materials in the earth’s crust and mantle.
Pahoehoe- Fast moving hot lava.
Aa- lava that is cooler and slower moving
Pyroclastse flow- when an explosive eruption hurls out ash, cinder, and bombs as well as gases.
Active- live volcano
Dormant- or sleeping volcano
Extinct- or a volcano that is unlikely to erupt.
Hot spring- ground water heated by a near by body of magma rises to the surface and collects in a natural pool.
Geothermal energy- water heated by magma can create a clean reliable energy source.
Shield volcano- places on the earth’s surface; thin layers of lava pour out of a vent and harden on top of previous layers. Such lava flows gradually build a wide, gently sloping mountain.
Cinder Cone Volcano- a steep cone shaped hill or mountain. If a volcanoes lave is thick and stiff it may produce ash cinders and bombs.
Composite Volcanoes- tall cone shaped mountains I nwhich layers of lava alternate with layers of ash.
Calderas- huge hole left by the collapse of a volcanic mountain.
Volcanic Neck- it forms when magma hardens in a volcano’s pipe.
Dike- Magma that forces itself across rock layers to harden.
Sill- when magma squeezes between layers of rock.
Batholith- mass of rock formed when a large body of magma cools inside the crust.
Like Earth, Venus has Volcanic Mountains and other features that are probably ade of thin, runny, lava. On Mars there are large shield volcanoes similar to those on Venus and Earth, as well as Cone shaped volcanoes and lava flows.
Io and Triton have volcanic features very different from those on Earth, Mars, and Venus.
- Reflection occurs when a wave bounces back.
- Refraction is the bending of waves due to a change in speed
- The low of refraction states that the angle of the incidence equals the angle of reflection.
- The bending of the waves around the edge of the barrier is called diffraction.
- Waves traveling through the same space at the same time interfere with each other.
- A wave produced at the resonant frequency of a material is a standing wave
- Sound is a form of energy that causes particles of medium to vibrate back and forth.
- Sound is a longitudinal wave.
- The speed of sounds on the properties of the medium. Speed travels faster at high temperatures, in more elastic mediums, and in less dense mediums.