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Pitch and Musical Instruments 1. How does the length of the vibrating medium affect the pitch? 2. If a string on a guitar is tightened, what happens to the pitch? 3. If a string on a guitar is shortened, what happens to the pitch? 4. If one string is thicker than the other at the same tension, what happens to the pitch 5. If two bottles have water in them, one more than the other, which will produce a higher pitch when someone blows over the opening? 6. If one chime is longer than another, which will produce the higher pitch. Amplification and Musical Instruments 1. Does amplification of sound waves change the pitch? If not, what does it change? 2. Using two different instruments, describe two ways that sound waves can be amplified. 3. Which materials seem to make the best amplifiers? May 2, 2013—Dynamic Earth Main ideas of plate tectonics: 1. Earth’s surface is composed of lithospheric plates 2. Plates are moving 3. Moving plates change the location of continents and alter the surface of the earth Plate Tectonics = Continental Drift + Sea Floor Spreading • 2. Sea floor moves to carry the continents • 3. Inner core/outer core—mantle—crust • 4. Come together (convergence), spread apart (divergence) and move past (transform) • 5. Along plate boundaries • 6. Earth’s inner core is solid, its outer core is liquid. The composition of both metal: iron and some nickel. Even though the core is hot enough to melt, it is under too much pressure to melt in the inner core. • 7. Earth mantle is solid igneous rock. • 8. The core is hotter than the crust. • 9. Convection in the mantle (hot mantle rises, cooler mantle sinks) • 10. The Decay of radioactive elements Seismic Waves and Dynamic Earth Learning Targets (Ch. 12) Can you… Compare and contrast the two types of body seismic waves (the P-waves and the S-waves) that travel through the Earth? Explain what causes earthquakes and its relationship to plate tectonics? Explain why three seismic stations are needed to find the epicenter of an earthquake? Explain what seismic evidence supports the idea that the outer core is liquid? Explain the sources of internal heat in the Earth? Explain what occurs in the mantle to cause the plates to move? Explain the three plate boundaries and what is the difference between convergence and divergence? Explain the difference between an epicenter and focus of an earthquake? Explain where most of the major earthquakes on Earth occur? Explain where the oceanic crust is youngest and oldest with respect to the mid-oceanic ridge? http://www.youtube.com/watch?v=L6jYgqL yIPw http://earthguide.ucsd.edu/eoc/teachers/t_t ectonics/p_paleomag.html Seismic Waves http://www.youtube.com/watch?v=_YLjIvJX hpg Mechanical waves that travel through the Earth or along its http://www.youtube.com/watch?v=FWsurface. TkpvKPl0 http://www.youtube.com/watch?v=0lAXStQ Cjr8 Cause • Any physical disturbance that causes the Earth to vibrate – Earthquakes (most commonly) – Volcanoes – Landslides (terrestrial or undersea) – Extraterrestrial impacts (asteroids – and meteorites) – Any disturbance! Barringer Meteor Crater, Arizona Iron-nickel meteorite 49,000 years old 50 m in diameter Impact speed 12.8 km/s 1.186 kilometers (.737 miles) in diameter 170 m in depth Earthquakes • Earthquakes occur when built-up stress is suddenly released. • Rupture or slippage of rock within the Earth produce seismic waves http://quake06. stanford.edu/c entennial/tour/s top11.html Earthquakes 2 Deformation • Moving plates place stress on the earth (1)compressive stress (push together) (2) a tension stress (pull apart) (3) a shear stress (moving past) (4) torsion stress (twisting) Earthquakes 2 Earthquake Waves • Earthquake waves travel out in all directions from a point where strain energy is released. This point is the focus. • The point on Earth’s surface directly above the focus is the epicenter. Earthquakes 2 Energy Release • When stress leads to strain, energy is released suddenly, and it causes rock to lurch to a new position. • A fault is a crack along which movement has taken place. • The sudden energy release that goes with fault movement is called elastic rebound. The Earth’s Surface is in constant motion! • The Theory of Plate Tectonics explains that the Earth’s surface is composed of several brittle lithospheric plates that move. • The surface of the Earth is under continuous stress from the motion of the plates. • Most earthquakes are caused by the motion of the lithospheric plates. Fig. 2-14, p. 38 Fig. 9-5, p. 191 Surface Waves 2 Body Waves— seismic waves that pass through the Earth Primary waves, also called P-waves, are longitudinal waves (compressional). • P-waves pass through solids and liquids • P-waves are faster than s-waves. Secondary waves, also called S-waves are transverse waves. • S-waves can travel through solids but not liquids • S-waves are slower than p-waves Body Fig. 9-8, p. 194 Longitudinal or compressional Or rarefactions transverse Fig. 9-9, p. 195 Fig. 9-10, p. 196 Gases emitted from the interior during this process are likely the source for the formation of the atmosphere and oceans. Fig. 1-10, p. 14 Internal Temperature of Earth Crust-mantle boundary 800-1200 C Core-mantle boundary 3500-5000 C Temperature of the Earth increases with depth (25 degrees C per km, closer to the surface) Fig. 1-10c, p. 14 Sources of Earth’s Internal Heat 1. Heat from Earth’s formation – gravitational contraction increased temperature of the interior) – Heat from extraterrestrial impacts (kinetic energy to thermal energy) 2. Heat from ongoing decay of radioactive nuclides (radioactive particles and energy increase temperature) Fig. 1-11, p. 15 The Earth’s Layers • Earth layers result from density differences between the layers caused by variations in composition, temperature, and pressure. • Core: metal (Fe and small amount of Ni) [10-13 g/cm3] • Outer liquid core • Inner solid core • Mantle: iron-rich rock (FeMg-Peridotite) [3.3–5.7 g/cm3] • Crust: aluminum and magnesium rich rock • Continental Crust: SiAl (rock) less dense [2.7 g/cm3] • Oceanic Crust: SiMa (rock) darker, more dense [3.0 g/cm3] Lithosphere and Asthenosphere • Lithosphere is the solid, brittle outer layer of the Earth composed of: – Oceanic and continental crust – Top part of the mantle • Asthenosphere is the plastic layer of the mantle directly below the lithosphere over which the lithospheric plates move. • The lithosphere is broken into many pieces called plates. Plate Boundaries • Divergent Plate Boundary (oceanic ridges and undersea volcanoes—see the Atlantic Ocean) spread apart • Convergent Plate Boundary (trenches and volcanic mountain chains—see the Andes Mountains) come together • Transform plate boundary (side-by-side plate motion—see the San Andreas Fault)--move past Three types of plate boundaries 1. Divergent plate boundary 2. Convergent Plate Boundary 3. Transform Plate boundary Fig. 1-14, p. 18 The Mechanism for Plate Motion is Convection in the Mantle Heat from the interior flows outward toward the crust Fig. 1-12, p. 15 What is the evidence that the Earth’s outer core is liquid? (See next slide) P-Waves P-waves and Swaves provide seismic evidence that the outer core is liquid and the inner core is solid Refraction: the bending of a wave as it passes from one medium to another S-Waves Caused by changes in wave speed Fig. 9-21, p. 210 Earth’s Interior 3 Shadow Zones • P-waves and S-waves travel through Earth for 105 degrees of arc in all directions. • Between 105 and 140 degrees from the epicenter, nothing is recorded. • This “dead zone” is termed the shadow zone. • This seismic pattern indicates that the outer core is liquid. Benioff Seismic Zone (associated with a subduction zone at a Convergent Plate Boundary) Pattern of earthquake occurrences indicates the location of the subducted limb of the lithospheric plate Fig. 2-13, p. 37 Fig. 2-19, p. 43 Fig. 2-23, p. 46 • http://videos.howstuffworks.com/howstuffw orks/230-how-tsunamis-work-video.htm http://www.uwiseismic.com/General.aspx?i http://www.geogateways.com/toolkit/ggima ges/tsunami1.jpg d=23 Earth’s Interior 3 Solid Inner Core • The fact that P-waves pass through the core, but are refracted along the way, indicates that the inner core is denser than the outer core and solid. • When pressure dominates, atoms are squeezed together tightly and exist in the solid state. • If temperatures are high enough, atoms move apart enough to exist in the liquid state, even at extreme pressures. Earthquakes 2 Surface Waves • Surface waves move in a more complex manner. • They can exhibit an up and down rolling motion, and also a side-to-side motion that parallels Earth’s surface. Earthquakes 2 Surface Waves Earthquakes 2 Earthquake Measurement • The Modified Mercalli scale ranks earthquakes in a range from I-XII, XII being the worst and uses eyewitness observation and postearthquake assessments to assign an intensity value. Earthquakes 2 Earthquake Measurement • The Richter magnitude scale uses the amplitude of the largest earthquake wave. • Richter magnitude is intended to give a measure of the energy released during the earthquake. Earthquakes 2 Earthquake Measurement • The table shows the global frequency of different magnitude earthquakes. Earthquakes 2 Levels of Destruction • Research has shown that poor building methods are the largest contributors to earthquake damage and loss of life. Earthquake Proofing • Although no building can be made entirely earthquake proof, scientists and engineers are finding ways to reduce the damage to structures during mild or moderate earthquakes. Earth’s Interior 3 Shadow Zones The Nature of Waves 1 Seismic Waves • Seismic waves are a combination of longitudinal (p-waves) and transverse waves (s-waves). They can travel through Earth and along Earth’s surface. • The more the crust moves during an earthquake, the more energy is released. Click image to view movie. http://www.youtube.com/watch?v=a7QqrFkiE7g http://www.youtube.com/watch?v=yOGoKCK17a4&feature=related http://www.forgefx.com/casestudies/prenticehall/ph/seismic/seismic-wavessimulator.htm http://aspire.cosmic-ray.org/labs/seismic/index.htm Seismic Waves The sudden release of energy within the Earth produces waves. http://www.youtube.com/watch?v=FW-TkpvKPl0 http://www.youtube.com/watch?v=0lAXStQCjr8&feature=related Seismic Waves • Seismic waves are produced by earthquakes when stresses build up by moving plates are suddenly released. • Body waves vs. surface waves • Interior waves produced by this disturbance include longitudinal waves or p-waves and transverse waves or s-waves. • P-waves are faster than s-waves, and can travel through solids or liquids. S-waves cannot travel through liquids. • The epicenter and focus of an earthquake can be calculated using seismic data from at least The Nature of Waves 1 Seismic Waves • Forces in Earth’s crust can cause regions of the crust to shift, bend, or even break. • The breaking crust vibrates, creating seismic (SIZE mihk) waves that carry energy outward. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Borussia 32 Dortmund FC Bayern 32 München FC Schalke 32 04 Borussia Mönchengla 32 dbach VfB Stuttgart 32 Bayer 04 32 Leverkusen Hannover 96 32 SV Werder 32 Bremen 1899 32 Hoffenheim VfL 32 Wolfsburg 1. FC 32 Nürnberg 1. FSV 32 Mainz 05 Sport-Club 32 Freiburg Hamburger 32 SV FC Augsburg32 1. FC Köln 32 Hertha BSC 32 1. FC Kaiserslauter 32 n 23 6 3 71:23 +48 75 CL* 21 4 7 71:21 +50 67 CL* 18 4 10 67:42 +25 58 CL* 16 8 8 46:24 +22 56 CL* Qual. 14 8 10 60:42 +18 50 EL* 13 9 10 47:43 +4 48 EL* Qual. 11 12 9 39:43 -4 45 EL* Qual. 11 9 12 46:52 -6 42 10 11 11 38:41 -3 41 12 5 15 42:56 -14 41 11 6 15 34:43 -9 39 9 11 12 47:48 -1 38 9 10 13 41:56 -15 37 8 11 13 35:56 -21 35 7 8 6 13 6 10 12 18 16 35:49 -14 37:67 -30 35:59 -24 34 30 28 Relegation Abstieg 4 11 17 21:47 -26 23 Abstieg