9-16-09 Science Notes: Ch. 1, section 1The Air Around You After the lesson, you should be able to 1. Describe the composition of the earth’s atmosphere. 2. State how the atmosphere is important to living things. Key Terms: Weather- condition of the earth’s atmosphere at a particular time and place Atmosphere- envelope of gases that surrounds the planet Ozone- form of oxygen that has 3 oxygens instead of 2. Water vapor- water in the form of gas. Composition of Atmosphere Nitrogen- 78% Oxygen – 21% All other gases-Carbon Dioxide, Water vapor, many other gases, particles and solids – 1% Nitrogen an element colorless, odorless gas 6th most abundant gas in the universe Most abundant gas in atmosphere - 78% mostly given off by volcanoes Oxygen Colorless Odorless Tasteless Denser than air Slightly soluble in water Poor conductor of heat and electricity Supports combustion but does not burn Extremely active, forming compounds with all the elements except the inert gases Preview-O3/ozone Ozone or trioxygen (O3) has three oxygen atoms. 2 kinds: Ground-level ozone - air pollutant with harmful effects on the respiratory systems of animals and humans. upper atmosphere ozone filters damaging ultraviolet light from reaching the Earth's surface. It is present in low concentrations throughout the Earth's atmosphere. Carbon Dioxide Carbon Dioxide 0.038% CO2 (O=C=0) Why is it important? Essential to life Plants need it to produce food and the plants are needed to give off oxygen for us to breathe. This is done through the process of photosynthesis (removes CO2) and respiration (releases CO2). Importance of the Atmosphere Earth’s Atmosphere makes conditions suitable for living things. Traps energy from the sun that allows water to exist as a liquid. End. Getting this! 1. Demonstrations- see sheet 2. Lake Nyos Story 3. Horseshoe Lake in California video clip Lake Nyos--The Deadly Eruption Horseshoe Lake-Short Video Clip http://bbs.keyhole.com/ubb/ubbthreads.p hp?ubb=showflat&Number=1070068&sit e_id=1#import 9-17-09 Ch.1, section 2 Air Pressure After the lesson, you should be able to… Identify some properties of air Name instruments that are used to measure air pressure Explain how increasing altitude affects air pressure and density Key Terms: Density Pressure Air pressure Barometer Mercury Barometer Aneroid Barometer Altitude Properties of Air Air has mass, density and pressure. Density-the amount of mass in a given volume Density – mass(g)/volume (ml) Pressure The force pushing on an area. The weight of the atmosphere exerts a force on surfaces. Air pressure -is the result of a column of air pushing down on an area. Air pressure is defined as the weight of the air in a column stretching from the surface to the top of the atmosphere. Balanced and Unbalanced Pressure- Measuring air pressure Barometer- instrument that measures air pressure Mercury Barometer-consists of a glass tube partially filled with mercury, with its open end resting in a dish of mercury Aneroid Barometer-measures changes in wind speed without using a liquid Mercury Barometer Aneroid Barometer Unit of Air Pressure Inches of Mercury – (if the column in a mercury barometer is 30 inches high, air pressure is “30 inches” Millibars – 1 inch of mercury = 33.87 millibars. 30 inches of mercury = 1,016 millibars. Barometer readings in tracking the weather The average air pressure world wide is 29.92 inches. A drop of less than an inch can signal a major storm A rise of less than an inch can signal fair weather. Understanding Pressure Pressure Demos and Discussion Questions Question 1- What is the relationship between altitude and air pressure? Question 2- Why is air pressure greater at sea level? Question 3- Is density higher or lower at high altitudes? Question 4- Areas with high altitudes, such as mountain ranges, usually have low or high pressure? Why? Question 5- Areas with low altitudes, such as areas at or below sea levels, usually have low or high pressure? Why? Altitude also affects density As you go up through the atmosphere, the density of the air decreases-meaning the molecules that make up the atmosphere are further apart at high altitudes than they are at sea level. 9-22-09 Ch. 1, sect. 3 Layers of the Atmosphere By the end of this section, you should be able to: Identify the four main layers of the atmosphere. Describe the characteristics of each layer. Layers of the Atmosphere Troposphere Stratosphere Mesosphere Thermosphere http://www.windows.ucar.edu/tour/link=/earth/Atmosphere/layers.html Meteoroid and Meteorite A meteoroid is a sand- to bouldersized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's atmosphere is called a meteor. If a meteoroid reaches the ground, it is then called a meteorite. Troposphere Tropo means “turning” or “changing” we live here conditions are more variable than in the other layers. layer where the weather occurs. Stratosphere Lower stratosphere is colder. Upper stratosphere is warmer- “good” ozone in middle absorbs energy from the sun, converts it into to heat, which warms the air. Mesosphere Meso means “middle” Layer that protects earth from being hit by most meteoroids (chunks of metal and stone from space). Thermosphere “thermo” means heat Outermost layer Thin air-0.001 percent as dense as at sea level. Divided into 2 layersIonosphere and Exosphere This is an image of the space shuttle as it is orbiting around the Earth. The space shuttle orbits in the thermosphere of the Earth. Ionosphere Lower layer of thermosphere Energy from sun causes gas molecules to become electrically charged particles called ions. Radio waves bounce off ions Light displays from particles from sun that enter ionosphere near poles. (Auroras) Exosphere Outer portion of thermosphere Video http://video.google.com/videosearch?q =aurora%20borealis# 9-23-09 Ch. 1,sect 4. Air Quality After the lesson, your should be able to… Identify the major source of air pollution Identify what causes smog and acid rain Describe what can be done to improve air quality. Air around us contains… Pollutants- harmful substances in air, water, soil. Sources of Pollution Natural Sources- Forest fires, soil erosion, and dust storms, pollen, mold, erupting volcanoes spewing dust, ashes and poisonous gases. Sources of Pollution Human Activities –Farming and construction. Most comes from burning of fossil fuels (coal, oil, gasoline, and diesel fuel) Burning produces Carbon Monoxide, Nitrogen Oxides, Sulfur Oxides Almost ½ comes from cars/motor vehicles. Smog and Acid Rain Burning of Fossil Fuels cause smog and acid rain London-Type fog- coal smoke combines with water droplets in humid air. Photochemical Smog Brown haze that develops in sunny cities. Formed by action of sunlight on pollutants (hydrocarbons and nitrogen oxides) Chemicals react to form brownish mixture of ozone and other pollutants. Acid Rain Rain that has more acid than normal. Forms from nitrous and sulfur oxides that combine with water in the air to form nitric acid and sulfuric acid. Can damage surfaces, lakes, ponds Improving Air Quality Laws have been passed to reduce air pollution Newer cars and power plants make less pollutants, but… There are still more cars on the road and more power plants burning fossil fuels. Air Quality Index http://www.bing.com/videos/search?q=air +quality+index&adlt=strict&docid=107593 7345675&mid=C502426E03905C3E0817 C502426E03905C3E0817&FORM=VIVR 10# Next- Effects of Pollution http://www.usatoday.com/weather/tg/wglobale/wglobale.htm Question of the Day: Without the Sun would Earth have weather? View online pictures of the the sun and the earth iJournal Question: What is energy? Where does the earth's energy come from? Observe a demonstration of how the Sun's energy reaches Earth and participate in a discussion about what you observed. Big Idea Statement: Weather is the Movement of Energy Complete Movement of energy learning tool 10-13-09 Ch.2, sect. 1 Energy in Earth’s Atmosphere Key Terms Electromagnetic waves Radiation Infrared Radiation Ultraviolet Radiation Scattering Greenhouse effect Energy from the Sun… Travels to earth as electromagnetic waves. Electromagnetic waves-a form of energy that moves through space. Classified by wavelength, or distance between the waves. Electromagnetic Spectrum Color the Electromagnetic Spectrum in your notes. Label Spectrum. Electromagnetic Waves http://www.colorado.edu/physics/2000/waves_ particles/index.html Water Waves http://www.colorado.edu/physics/2000/waves_ particles/waves.html Stadium Waves http://www.colorado.edu/physics/2000/waves_ particles/stadium_wave.html Radiation- Direct transfer of energy by electromagnetic waves. Most energy from the sun travels to Earth in form of visible light and infrared radiation. a small amount arrives as ultraviolet radiation. Infrared Radiation ↓ Visible Light ↓ ↓ Ultraviolet Radiation Visible Light Red, Orange, Yellow, Green, Blue and Violet Red has the longest wavelength. Violet has the shortest wavelength Non-Visible Radiation Infrared Radiation-has wavelength are longer than red light. Not visible but felt as heat. Ultraviolet Radiationwavelengths shorter than violet. Can cause sunburns, skin cancer and eye damage. Infrared Radiation ↓ Visible Light ↓ ↓ Ultraviolet Radiation Energy in Atmospheresunlight Some sunlight is absorbed or reflected by atmosphere before it can reach the surface. Rest of the sunlight passes through atmosphere to surface. Absorption Ozone layer in stratosphere absorbs most ultraviolet radiation. Water vapor and CO2 absorbed infrared radiation/ Clouds, dust, and other gases absorb energy. “Scattering” Dust particles and gases in atmosphere reflect light in all directions. Energy at Earth’s Surface ½ sun’s energy is absorbed by land and water and changed into heat. When earth’s surface is heated, it radiates most of the energy back into the atmosphere as infrared radiation. Greenhouse Effect Process by which gases hold heat in the atmosphere- much of the infrared radiation can not travel back to space so it is absorbed by water vapor, carbon dioxide, methane and other gases. 10-14-08 Lab Notebook: Heating Earth’s Surface Problem How do the heating and cooling rates of sand and water compare? Research Heating –process of warming something: Cooling-To make less warm. Hypothesis Which do you think will heat up faster? If I increase/decrease the rough texture/liquid form…, then the rate of heating will increase/decrease. Experiment -Read pg 40-41 in text. Data Table See Word Document or text page 40. Analysis See page 41 in text. Answer questions 1-8 Conclusion Two statements. First statement –tells whether your hypothesis was correct of not. Second statement-hypothesis written in past tense. 10-17-09 Ch.2, sect. 2 Heat Transfer Key Terms: Temperature Thermal energy Thermometer Heat Conduction Convection Convection currents Thermal Energy and Temperature Temperature- average amount of energy of motion of each particle in a substance Thermal energy- total energy of motion. i.e- hot tea has more thermal energy in tea pot than hot tea in cup because it has more particles. Measuring Temperature A thermometer measures air temperature. (thin glass tube with a bulb at one end that contains liquid or mercury) When air temp increases, the liquid in bulb increases and expands and rises Temperature Scales Temperature is measured in units called degrees Common scales Celsius freezing point –0oC boiling point – 100oC Fahrenheit freezing point –32oF boiling point – 212oF How is heat transferred? Radiation-direct transfer of energy by electromagnetic waves (space) Conduction- direct transfer (touching) of heat of one substance to another. Convection-transfer of heat by the movement of fluid. Heating in the Troposphere Radiation, Conduction, Convection Currents heat troposphere Radiation- sun heats earth’s surface Conduction- heat touches the ground and warms it Convection Currents-Upward movement of warm air and downward movement of cool air. What does this look like? http://www.classzone.com/books/earth_scienc e/terc/content/visualizations/es1903/es1903pa ge01.cfm?chapter_no=visualization Land and sea breeze http://www.hainesport.k12.nj.us/educatio n/sctemp/6d5952d0214ba64abedf609ff1 a9d0c0/1256043301/arv3Sea-nLandBreezeImage4wkst.pdf Next- in your notebook, diagram the following: The heating of the troposphere. Label Radiation, Conduction, Convection Currents. Include Arrows and Direction. Title: Heat Transfer Lab (40-41) Purpose: Research: Statement on heating Hypothesis: Guess on heating and cooling of sand and water. Experiment: Include data table Summarize what you did. Analysis/Conclusion: Answer Questions in complete sentences. 10-22-08 Ch.2, sect. 3 Wind Part 1 Key Terms Wind Anemometer Wind-Chill Factor Local Winds Sea Breeze Land Breeze Global Winds Coriolis Effect Latitude Jet Stream Wind Horizontal movement of air from an area of high pressure to an area of low pressure. Caused by differences in air pressure-unequal heating of the earth’s surface heated by the sun’s rays. How does heating impact pressure? Measuring Wind Winds are described by their direction and speed Name of the wind tells you where the wind is coming from “South wind”-blows from the south to the north “West wind” blows from the _____ to the_____? Wind speed measured by anemometer-has 3 or 4 cups that spin on an axel that is attached to a meter that shows wind speed. Wind Chill Factor Wind blowing over your skin removes body heat Increased cooling a wind can cause is the Wind Chill Factor Local winds Winds that blow over short distances-caused by unequal heating of Earth’s surface within a small area (these form when large scale winds are weak) Sea Breezes and Land Breezes Sea Breeze Happens during the day- it is a local wind that blows from the ocean or lake toward the land. How does this happen? Draw it… Sea Breeze- Draw it Land Breeze Happens at night- it is a local wind that blows from the land to the ocean or lake. How does this happen? Draw it. Land Breeze-Draw it 10-23-09 Ch.2, sect. 3 Wind Part 2 (will need red and blue colored pencils) Global Winds Occurs over large areas. Created by unequal heating of the Earth’s surface by the sun’s rays. Global Convection Currents Temp between the equator and poles produce giant convection currents Warm air rises at the equator- low pressure. Cold air sinks at the poleshigh pressure Warm air rises at the equator- low pressure. Cold air sinks at the poleshigh pressure Important to note- Because the Earth is rotating, these global winds do not blow in a straight line. What? 1. Draw/cut circle. 2. Pressing lightly, try to draw a straight line from the center of the circle while your partner turns the circle… What happens? – This effect is called the Coriolis Effect. Gaspard-Gustave Coriolis, a French scientist who described it in 1835, Effect of Coriolis Effect on Global Winds Global winds in the northern hemisphere turn to the right of it’s path. (deflected to the right) Global winds in the southern hemisphere turn to the left of it’s path. (deflected to the left) Coriolis Effect in Northern and Southern Hemisphere. Draw it. 1. Movement of wind without Coriolis effect (pencil) 2. Movement of wind with the Coriolis effect (red and blue pencil) The Coriolis Effect Global Wind Belts. Doldrums Horse Latitudes Trade Winds Prevailing Westerlies Polar Easterlies See sheet… let’s look at this. *Doldrums-calm areas where warm air rises. Near the equator. Sun heats the surface strongly. *Horse Latitude-calm areas of falling air. About 30O north and south of the equator. Latitude-the distance from the equator, measured on degrees. Warm air rises at the equator and flows north and south. At 30o north and south, air stops moving towards poles and sinks. *Trade Winds-blows from the horse latitudes toward the equator. When the cold air over the horse latitudes sinks, it produces high pressure surface winds that blow toward the equator and away from it. Between 30O north and south latitudes and the equator. *Prevailing Westerlies-blows away from the horse latitudes. In the midlatitudes. Between 30O and 60O north and south, winds that are blow towards the poles are turned east by the Coriolis effect. *Polar Easterlies-blows cold air away from the poles. Cold air near the poles sink and flow back to the lower latitudes. Coriolis effect shifts the polar winds to the west. Polar easterlies meet the prevailing westerlies at about 60o north and south latitudes. Jet Streams-bands of high speed winds about 10 kilometers above Earth’s surface. Global Wind Sheet – fill in. attach to NB 10/30-31/08 Ch.2, sect. 4 Water in the Atmosphere Key Terms Water cycle Humidity Psychrometer Dew point Evaporation Relative humidity Condensations Cumulus Cirrus Stratus Water cycle Movement of water between the atmosphere and the Earth’s surface. Evaporation-the process by which water molecules in liquid water escape into the air. Water Cycle Review http://livingclassrooms.org/slurrp/wat ercycle.html Know this… Air has water vapor in itmeasurement of it is called “Humidity” Air’s ability to hold water depends on its temperature. Warm air can hold more water vapor than cool air. How Clouds Form 1. Warm, moist air rises from the surface. As air rises, it cools. 2. At a certain height, air cools to the dew point and condensation begins. 3. Water vapor condenses on tiny particles in the air, forming a cloud. What would this look like? Draw it. Step 1. Step 2. Step 3 Insert picture on how clouds form Role of Cooling As air cools, the amount of water vapor it can hold decreases, so the water vapor condenses into tiny droplets of water or ice crystals. Temperature that condensation begins is called Dew Point. Dew point above freezing-water droplets Dew point below freezing-ice crystals Role of Particles Particles, such as salt crystals, dust from soil, and smoke are needed for the water vapor to condense on. Cloud in a Bottle Demo http://www.chias.org/www/edu/activiti es/activity1/activity1.html http://questgarden.com/46/09/1/0701 30184558/files/Making_Your_Own_Cl oud.doc Types of Clouds Clouds are classified by shape: cirrus, cumulus, and stratus. Clouds are classified by their altitude. Cirrus Clouds Wispy, feathery clouds form at high levels above 6 km where the temperatures are very low. Cirrocumulus are clouds that indicate a storm its way. Cumulus Clouds- Looks like fluffy piles of cotton. “Cumulus” means heap or “mass” Form less than 2 km above ground and may grow in size and height as they extend upwards as much as 18 km. Stratus Clouds Clouds that form in flat layers. Usually cover most or part of the sky. May produce rain, drizzle, or snow- they are then called Nimbostratus clouds. “Nimbus” means rain. Altocumulus and Altostratus Clouds “Alto” means high- but these are middle-level clouds that are higher than regular cumulus and stratus clouds but lower than cirrus and other high clouds. Fog Clouds that forms near the ground. Forms when ground cools at night after a warm, humid day. Fog Demo http://www.youthonline.ca/crafts/mak efog.shtml 10/31/09 Ch.2, sect. 5 Precipitation Key Terms Precipitation Rain Sleet Freezing Rain Snow Hail Precipitation Any form of water that falls from clouds and reaches Earth’s surface Not all clouds produce precipitation Cloud droplets or ice crystals must be heavy enough to fall through air. Types of Precipitation Rain Sleet Freezing Rain Snow Hail Rain Drops of water that are at least 0.5 mm in diameter. Sleet Occurs when rain drops fall through a layer of air that is below freezing and rain drops freeze into particles of ice. Ice crystals that are 5 mm in diameter are called sleet. Freezing Rain Rain drops that freeze when they touch a cold surface. Snow- Water vapor in a cloud is converted into ice crystals called snow flakes. Hail Round pellets of ice larger than 5 mm in diameter. Start as small pellets inside of cumulonimbus clouds and they grow larger as they are tossed up and down. When they become heavy, they fall to the ground. Modifying Precipitation Droughts-long periods of unusually low precipitation Cloud Seeding- tiny crystals of silver iodide and dry ice (solid carbon dioxide) are sprinkled into clouds from airplanes. http://video.google.com/videosearch?q=cloud%20seeding&safe=active# Measuring Precipitation Snowfall Measurements- using a measuring stick or by melting collected snow and measuring the depth of the water it produces. Rain Measurements- using a rain gaugean open ended can or tube that collects rainfall. Ch. 3. Weather Patterns Key Terms Air Mass Tropical Polar Maritime Continental Front Occluded Cyclone Anticyclone Air Mass huge body of air that has similar temperature, humidity, and air pressure at any given height Types of Air Masses Tropical-warm air masses that form in the tropics and have low air pressure Polar-cold air masses with high air pressure that form north of 50° north latitude and south of 50° south latitude Types of Air Masses Maritime-air masses that form over oceans Continental-air masses that form over land Types of Air Masses Maritime Tropical-warm, humid air masses that form over tropical oceans Maritime Polar-cool, humid air masses that form over the icy North Pacific and North Atlantic oceans Types of Air Masses Continental Tropical-hot, dry air masses that form mostly in summer over dry areas of the Southwest and northern Mexico Continental Polar-large continental polar air masses that form over central and northern Canada and Alaska How Air Masses Move: Prevailing Westerlies-the major wind belts over the continental United States, generally push air masses from west to east Jet Streams-bands of high-speed winds about 10 kilometers above Earth’s surface Front-the boundary where unlike air masses meet but do not mix Types of Fronts Cold Fronts-a fast moving cold air mass overtakes a warm air mass Warm Front-A warm air mass overtakes a slow moving cold air mass Stationary front-cold and warm air masses meet, but neither can move the other Occluded front-a warm air mass is caught between two cooler air masses Occluded-when the warm air mass is cut off Cyclones and Anticyclones Cyclone- a swirling center of low air pressure Anticyclones-high-pressure centers of dry air http://video.google.com/videosearch?q=a ir+mass+and+fronts&emb=0&aq=3&oq= air+mass&safe=active#q=Tornado&view= 2&emb=0 11-23-09 Ch 4, sect. 1 What Causes Climate? Key Terms Climate Microclimate Tropical Zone Polar Zone Temperate Zone Marine climate Continental Climate Windward Leeward Monsoon Climate The average temperature, precipitation, winds, and clouds in an area. Scientists use two main factors to describe the climate of a region -precipitation and temperature. Factors Affecting Temperature Latitude Altitude Distance from large bodies of water, ocean currents. Latitude Climates near the equator are warmer than areas further from the equator because the sun’s rays hit Earth’s surface more directly. Over the poles, same amount of solar radiation is spread over a large area bringing less warmth. Earths 3 Temperature Zones Tropical Zones-near the equator. Between 23.5 north and south of the equator. Polar Zones- extend from 66.5 to 90 north and south latitudes. Temperate Zones- between tropical and polar zones. In the summer rays strike temperate zones more directly. In the winter, rays strike at a lower angle. Altitude In the troposphere, temperature decreases about 6.5 Celsius degrees for every 1 kilometer increase in altitude. Therefore, you should be able to explain why Mt. Kilimanjaro, which is located in Africa has a cool climate even though it is located at low latitudes. Distances from Large Bodies of Water Oceans or large bodies of water affect temperatures- they can greatly moderate or make less extreme. Why? Distances from Large Bodies of Water Oceans or large bodies of water affect temperatures- they can greatly moderate or make less extreme. Why?-water heats and cools more slowly than land, therefore winds prevent extremes of hot and cold in coastal regions. Distances from Large Bodies of Water Much of West Coasts of North America, South America and Europe have mild Marine climates with mild winters and cool summers. Centers of North America, Asia, most of Canada and Russia are too far inland to be warmed or cooled by the ocean. -These experience Continental climates with more extreme temperate than marine climates. Winters are cold, while summers are warm or hot. Ocean Currents Marine Climates are influence with the ocean currents: • warm ocean currents move from tropics to the poles. • warm ocean warms the air above it and the warm air moves over the land. • cold currents move from poles to the equator. Cold currents bring cool air. Ocean Current Pause Ocean of Plastic http://video.google.com/videosearch?q=texas+sized+trash+in+ocean&ww w_google_domain=www.google.com&emb=0&aq=2m&oq=trash+in+ocea n&safe=active#q=trash+in+ocean&view=2&emb=0&safe=active&start=30 &qvid=Ocean&vid=7273400233017880628 Green Chemistry and Ocean Trash http://video.google.com/videosearch?q=texas+sized+trash+in+ocean&ww w_google_domain=www.google.com&emb=0&aq=2m&oq=trash+in+ocea n&safe=active#q=trash+in+ocean&view=2&emb=0&qvid=trash+in+ocean &vid=-645736240970897881 Ocean Current Career http://www.diveintoyourimagination.com/blogsection/ Factors Affecting Precipitation The main factors that affect precipitation are prevailing winds, the presence of mountains, and seasonal winds. Prevailing Winds Weather patterns depend on movement of huge cold/warm/ dry/moist air masses. Amount of water vapor in the air mass influences how much rain or snow will fall. Winds that blow inland from oceans carry more water vapor than winds that blow from over land. And water vapor brings precipitation. Mountain Ranges A mountain range in the path of prevailing winds can influence where precipitation forms. When humid air blows from ocean to mountain, air rises, cools, water vapor condenses, forming clouds and rain or snow falls. This is the windward side. What does “windward” look like? Draw it. Mountain Ranges By the time the air has moved over the mountains, it has lost water vapor and is now cool and dry. This is the leeward side of the mountain-downwind. Little precipitation falls here. What does “leeward” look like? Draw it Seasonal Winds Similar to land breezes and sea breezes but occur over wider areas. Sea and land breezes over large region that change direction with the seasons are called monsoons. Monsoon summer in South and Southeast Asia- big “sea breeze” Sea breeze blows steadily inland from ocean all summer. Air blowing in is warm and humid. Humid air rises over the land and cools causing the water vapor to condense into clouds, producing heavy rains. Seasons Winter - big “land breeze” Land cools and becomes colder than ocean, “land breeze” blows steadily from the land to the ocean and these winds carry little moisture. **Regions affected by monsoons receive little rain in the winter. Video- Career in Ocean Studies??? http://www.diveintoyourimagination.com/b logsection/ Ocean of Plastic http://video.google.com/videosearch?q=texas+sized+trash+in+ocean&ww w_google_domain=www.google.com&emb=0&aq=2m&oq=trash+in+ocea n&safe=active#q=trash+in+ocean&view=2&emb=0&safe=active&start=30 &qvid=Ocean&vid=7273400233017880628 Green Chemistry and Ocean Trash http://video.google.com/videosearch?q=texas+sized+trash+in+ocean&ww w_google_domain=www.google.com&emb=0&aq=2m&oq=trash+in+ocea n&safe=active#q=trash+in+ocean&view=2&emb=0&qvid=trash+in+ocean &vid=-645736240970897881 Ocean Current Career http://www.diveintoyourimagination.com/blogsection/ 11-30-09 Ch 4, sect. 2 Climate Regions Key Terms Rain Forest Desert Humid Subtropical Tundra Savanna Steppe Subarctic Permafrost Scientists classify climates according to two major factors: temperature and precipitation. There are six main climate regions: tropical, rainy, dry, temperate marine, temperate continental, polar, and highlands. Tropical Rainy Tropical Wet-Always hot and humid, with heavy rainfall (at least 6 centimeters per month) Tropical Wet and Dry-Always hot; alternating wet and dry seasons; heavy rainfall in the wet season Dry Climates Semiarid-Dry but receives about 25 to 50 centimeters of precipitation per year Arid-Desert with little precipitation, usually less than 25 centimenters per year Temperate Marine Climate Marine west coast-mild winters and cool summers, moderate precipitation all year Mediterranean-warm, dry summers and rainy winters Humid Subtropical-hot summers and cool winters Temperate Continental Humid Continental-hot, humid summers with moderate precipitation all year round Subarctic-short, cool summers and long, cold winters; light precipitation, mainly in the summer Polar Climates Ice Cap-Always cold, average temperature at or below 0 degrees Celsius Tundra-Always cold with a short, cool summer-warmest temperature about 10 degrees Celsius Highlands Generally cooler and wetter than nearby lowlands; temperature decreasing with altitude. Focus on the climates-With your partner, you will RESEARCH the climate zones (in your notes) and find the following: 1. A picture of a city or town or area in that climate zone. Include the name of the city/town/area/country/state, and population. (you may use pgs 120-121 to help you with cities/towns). 2. Write short description of how the people “make their living”/live in these climate zones. 3. Explain: How does their way of “making a living” make sense to the climate zone that they live in. Attach # 1,2, and 3 to your notes. 12-11-09 Ch 4, sect. 3 Long-Term Changes in Climate Key Terms Ice Age Sunspot Studying Climate Change Scientists follow this principle when studying ancient climates: If plants or animals today need certain conditions to live, then similar plants and animals in the past also required those conditions. Pollen Each plant has a particular type of pollen. Scientists can drill into the bottom of lakes and find pollen that was present years ago and they can see the type of climate that allowed the plant to grow. Tree Rings Layers showing the tree’s growth. In cool climates-thickness of tree rings depends on length of warm growing season. In dry climates-thickness of tree ring depends on amount of rainfall. From data, scientists can tell years of warm or cool, wet or dry. Activity on tree rings after notes. Ice Ages In earth’s history, climates have gradually changed. There have been periods of warm and cold. Cold periods- Ice Ages or “glacial episodes” During Ice Age, huge sheets of glaciers covered large parts of Earth’s surface. Ice Age During the ice age, much of the water was frozen as ice so the average sea level was lower than it is today. Possible explanations for the causes of Climate Change- Draw this # 1. Earth’s Position-earth’s tilt and orbit around the sun change over time. Possible explanations for the causes of Climate Change. Draw this # 2. Solar Energy- changes in number of sun spots on the sun. Sun produced more energy with sun spots. Possible explanations for the causes of Climate Change. Draw this. # 3. Volcanic Activity- volcanic eruptions releasing huge amounts of gas into the atmosphere which could filter incoming solar radiation and lower temperatures. Movement of Continents Continents have not always been located where they are now. At one time, most of the land was part of a single continent called Pangaea-and Pangaea broke apart and continents moved to different latitudes on the earth. More on Pangaea to come in next unit. 12-15-09 Ch 4, sect. 4 Global Changes in the Atmosphere Key Terms El Nino La Nina Global Warming Greenhouse Gas Chlorofluorocarbon Short Term Climate Change El Nino and La Nina are short term changes in the tropical Pacific Ocean and are caused by changes in ocean surface currents and prevailing winds. El Nino-Warm water event La Nina-Cold water event El Nino Warm water event that begins when an unusual pattern of winds forms over the western Pacific. Warm water moves eastward to South American coast. Disrupts cold ocean current-brings sever conditions- droughts or heavy rains in different parts of the world La Nina Cold water event When surface waters are colder than normal. Brings colder winters and greater precipitation to the Pacific Northwest and north central United States. Also brings greater hurricane activity in western Atlantic. Short Video- Weather Patterns vs Global Warming. El Niño connection. http://www.youtube.com/watch?v=5uk9nwtAOio&feature=related La Nina http://www.youtube.com/watch?v=U7lw2RsxhEs&feature=related Changing levels of CO2 Scientists believe caused by increased human activities, such as the burning of wood, coal, oil and natural activities have led to global warming. Climate Variation Hypothesis Some scientists think global warming is due to changes in energy of the sun producing warmer and cooler climates. Possible Effects of Global Warming Positive- places too cold could become farmland. Less positive-current farmlands could cause water to evaporate making them to dry for farming. Possible Effects of Global Warming Review of Global Warming: http://www.youtube.com/watch?v=_XDhuDEWSu4&feature=related Increased water temperature could increase strength of hurricanes. Ice could melt causing sea levels to rise flooding low lying coastal areas. Ozone Depletion Caused by chlorofluorocarbons, CFC’s which are used in air conditioners and refrigerators, cleaners, electronic parts, chemical in aerosol cans. Results in decreased ozone and increase amount of ultraviolet radiation that reaches the earth. Next El Nino and La Nina reading-complete with your partners. 1-4-10 Ch 1, sect. 1 Earth’s Interior The Science of Geology Geologists are scientists who study the forces that create Earth’s features and search for clues about earth’s history. They study the chemical and physical characteristics of rock. Studying Surface Changes: Geologists divide the forces that change the surface of the earth into two groups: →Constructive forces: shape the surface by building up mountains and landmasses. →Destructive forces: are those that slowly wear away mountains and, eventually, every other feature on the surface. In this picture, what formation shows evidence of the constructive force? destructive force? History- Two hundred years ago, geologists knew: that the Earth is a sphere with a radius at the equator more that 6,000 kilometers there are seven great landmasses, called continents, surrounded by oceans. that the continents are made up of layers of rock. But there were unanswered questions: How old is the earth? How has the Earth’s surface changed over time? Why are there oceans, and how did they form? Finding Indirect Evidence: Geologists can not observe Earth’s interior directly. They rely on indirect methods instead… For example- when earthquakes occur, they produce seismic waves. Geologists record the seismic waves to study how they travel through the earth. A Journey to the Center of the Earth Temperature: Increases as the depth increases (towards the center of the earth). Pressure: Increases as the depth increases (towards the center of the earth). Three main layers make up the Earth’s interior: the crust, the mantle, and the core. Each layer has its own conditions and materials. The Crust: - the layer of rock that forms Earth’s outer skin. - thinnest layer 5 to 40 kilometers thick. - crust beneath the ocean is basalt. Basalt is a dark, dense rock with a fine texture - crust beneath the continents is granite. Granite has larger crystals than basalt and is not as dense*. (fix typo) The Mantle: -at a depth between 5 to 50 kilometers beneath the surface. -The uppermost part of the mantle and the crust together is called the lithosphere. Lithos means “stone”. It is brittle. -the lower most part of the mantle is called the asthenosphere. Asthenes mean “weak.” It is soft and flows slowly The Core: -Earth’s core consists of two parts. The outer core and the inner core. -the outer core is a layer of molten metal that surrounds the inner core. -the inner core is a dense ball of solid metal. Earth’s Magnetic Field: Currents in the liquid outer core force the solid inner core to spin. The inner core spins faster than the outer core. 1-6-10 Chapter 1- Plate Tectonics Section 2-Convection Currents The movement of energy from a warmer object to a cooler object is called heat transfer. How is heat transferred? Radiation-direct transfer of energy by electromagnetic waves (space) Conduction- direct transfer (touching) of heat of one substance to another. Convection-transfer of heat by the movement of fluid. Convection current is the flow that transfers heat within in a fluid. The heating a cooling of the fluid, changes in the fluid’s density, and the force of gravity combine to set convection currents in motion. Convection in Earth’s Mantle Heat from Earth’s mantle and core causes convection current to form in the asthenosphere. 1-11-10 Chapter 1-Plate Tectonics Section 3-Drifting Continents If you were to look at a modern world map, you would notice how the coasts of Africa and South American look as though they could fit together like jigsaw puzzle pieces. Theory of Continental Drift Wegener’s hypothesis was that all the continents had once been joined together in a single land mass and have since drifted apart. Wegener named this super continent Pangaea, meaning “all lands.” According to Wegener, Pangaea existed about 300 million years ago. Over tens of millions of years, Pangaea began to break apart and slowly move over toward their present day locations, becoming the continents that they are today. *Continental Drift- Wegener’s idea that the continents slowly moved over Earth’s surface. Wegener gathered evidence from different scientific fields to support his ideas about continental drift. He studied landforms, fossils, and evidence that showed how the Earth’s climate had changed over many millions of years. In 1915, he published his evidence in a book called The Origin of Continents and Oceans. Wegener’s Evidence for Continental Drift Evidence from Landforms: Mountain ranges and other features on the continents provided evidence for continental drift. Example- the mountain ranges in running east to west in South Africa line up with a mountain range in Argentina. European coal fields match up with similar coal fields in North America. Evidence from Fossils: A fossil is any trace of an ancient organism that has been preserved in rock. *Example-Glossopteris, a fern like plant that flourished 250 million years ago, have been found in rocks in Africa, South America, Australia, India, and Antarctica. These seeds were very large, so they could not have been carried by the wind, and they were to fragile to have survived a trip by ocean waves. Evidence from Climate: Wegener used evidence of climate change to support his theory. *Example. Spitsbergen lies in the Arctic Ocean north or Norway. It currently has a harsh cool climate, but fossils of tropical plants are found on Spitsbergen. In mild South Africa of today, deep scratches in rocks showed that continental glaciers once covered South Africa. According to Wegener, Earth’s climate has not changed. Instead, the positions of the continents have changed. Scientists Reject Wegener’s Theory. Wegner could not provide a satisfactory explanation for the force that pushes or pulls the continents. Because Wegener could not identify the cause of continental drift, most geologists rejected his idea. In the early 1900’s, many geologists thought that the Earth was slowly cooling and shrinking. According to this theory, mountains formed when the crust wrinkled like the skin of a dried up apple. Wegener said that if this theory was correct, then mountains should be found all over Earth’s surface- but mountains usually occur in narrow bands along the edges of continents. 1–13-10 Chapter 1-Plate Tectonics Section 4-Sea Floor Spreading Mapping the Mid-Ocean Ridge The East Pacific Rise is one part of the mid ocean ridge, the longest chain of mountains in the world. In the mid 1900s, scientists mapped the mid-ocean ridge using sonar. Sonar is a device that bounces sound waves off under water objects and then records the echoes of these sound waves. Most of the mountains in the mid ocean ridge lie hidden under meters of water; however, there are places where the ridge pokes above the surface-the island part of Iceland. Evidence for Sea Floor Spreading Harry Hess studied the mid ocean ridge. In 1960, Hess suggested that the ocean floors move like conveyor belts, carrying the continents along with them. This movement begins at the mid ocean ridge and forms cracks in the oceanic crust. At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge. Hess called this process sea floor spreading. Picture of Sea Floor Spreading Evidence to support Sea Floor Spreading Evidence from Molten Material In the 1960’s scientist found evidence that new material is erupting along the mid-ocean ridge. On the ocean floor, scientists saw strange rocks that looked like toothpaste squeezed from a tube. These rocks can only form when molten material hardens quickly erupts under the water. Evidence from Magnetic Stripes When scientists studied patterns in the ocean floor, they found more support for the sea-floor spreading. Evidence shows that the Earth’s magnetic poles have reversed themselves. This last happened in 780,000 years ago. Scientist discovered that rock that makes up the ocean floor lied in a pattern of magnetized “stripes.” Evidence from Drilling Samples The final proof of sea floor spreading. Glomar Challenger, a drilling ship built in 1968. Samples from the floor were brought up from the pipes and scientists determine the age of the rocks in the samples. They found that the further away from the ridge are the older and the ones closest to the center were the youngest. Subduction at Deep-Ocean Trenches How can the ocean floor keeping getting wider and wider? The ocean floor generally does not just keep spreading. The ocean floor plunges into deep-ocean trenches forms where the oceanic crust bends downward. Subduction- where there are deep –ocean trenches, subduction is the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle. Convection currents under the lithosphere push new crust that forms at the mid ocean ridge away from the ridges and toward a deep-ocean trench. At deep-ocean trenches, subduction allows part of the ocean floor to sink back into the mantle, over tens of millions of years. Subduction and Earth’s Oceans: The process of subduction and sea floor spreading can change the size and shape of the oceans. *Subduction in the Pacific Ocean: The vast Pacific Ocean covers almost 1/3 of the planet. Yet it is still shrinking because a deep ocean trench can swallow more oceanic crust that the mid-ocean ridge can produce. *Subduction in the Atlantic Ocean: The Atlantic Ocean is expanding. It has only a few short trenches so the spreading ocean floor has virtually nowhere to go. 1–19-10 Chapter 1-Plate Tectonics Section 5- Plate Tectonics A Theory of Plate Motion Canadian scientist J. Tuzo Wilson observed that there are cracks in the continents similar to those in the ocean floor. In 1965, Wilson proposed that the lithosphere is broken into separate pieces called plates. . The theory of plate tectonics- *The plates of the lithosphere float on top of the asthensosphere. *Convection plates rise in the asthenosphere and spread out beneath the lithosphere causing the movement of Earth’s plates Plate Boundaries: Edges of different pieces of the lithosphere meet at lines called plate boundaries. Faults- are breaks in the earth’s crust where rocks have slipped passed each along the boundaries. Transform Boundaries Crust is neither created nor destroyed. A place where two plates slip past each other, moving in opposite directions. Divergent Boundaries The place where two plates move apart. -Most divergent boundaries occur at the mid ocean ridge as sea floor spreading occurs. -Divergent boundaries also occur on land-called a rift valley. For example, the Great Rift Valley in East Africa. Convergent Boundaries The place where two plates come together, or converge. When two plates converge, the result is called a collision. When two plates collide, the density of the plates determines which one comes out on top. Oceanic crust (made mostly out of basalt) is denser than Continental crust (made mostly out of granite). The Continents Slow Dance Plates move at slow rates- from one to ten centimeters per year. http://oceansjsu.com/105d/exped_shakin/3.html Ch 2, sect. 1 Earth’s Crust in Motion Stress in the Crust An earthquake is the shaking and trembling that results from the movement of rock beneath earth’s surface. The movement of Earth’s plates create powerful forces that squeeze or pull the rock in the crust- these are examples of stress. Stress-a force that acts on a rock to change its shape or volume. Types of stress: Shearing, Tension, and Compression Shearing: Stress that pushes a mass of rock in two opposite directions. Tension: Stress that pulls on the crust, stretching rock so that it becomes thinner in the middle. Compression: Stress that squeezes rock until it folds or breaks. Any change in the volume or shape of Earth’s crust is called deformation. Picture of 3 types of stress Kinds of Faults A fault is a break in the Earth’s crust where slabs of crust slip past each other. Faults usually occurs along plate boundaries, where the forces of plate motion compress, pull, or shear the crust so much that the crust breaks. Strike-Slip Faults- created by shearing. The rocks on either side of the fault slip past each other side ways with little up or down motion. A strike slip fault that forms the boundary between two plates is called a transform boundary. Normal faults- tension forces in the crust cause normal faults. In a normal fault, the fault is at an angle, so one block of rock lies above the fault while the other block lies below the fault. Hanging wall- Footwall- When movement occurs along a normal fault, the hanging wall slips downward. Reverse Faults- Compression forces produce reverse faults. The fault has the same structure as a normal fault, but the blocks move in opposite direction. Skipping Friction Along Faults and Mountain Building Normal Fault picture Reverse Fault Picture Ch 2, sect. 2 Measuring Earthquakes An earthquake starts at one particular point. The focus is the point beneath Earth’s surface where the rock that is under the stress breaks, triggering an earthquake. The point on the surface directly Seismic Waves are vibrations that travel through Earth carrying energy released during an earthquake. The seismic waves move like ripples in a pond. Seismic waves carry the energy of an earthquake away from the focus, through Earth’s interior, and across the surface. Three categories of seismic waves: P waves, S waves, Surface waves. P waves Primary waves. The first to arrive. Earthquake waves that compress and expand the ground like an accordion. Travels through solids and liquids S waves Secondary waves Earthquake waves that vibrate side to side as well as up and down When they reach the surface, they shake structures violently. Travels through solids not liquids Surface Waves When P and S waves reach the surface, some are transformed into surface waves. These move more slowly than P and S waves These produce severe ground movements. Measuring Earthquakes Three ways of measuring earthquakes: Mercalli scale, the Richer scale, the moment magnitude scale. Mercalli scale-developed in the early 20th century. Developed to rate earthquakes according to their intensity. Richter scale-rating the size of seismic waves as measured by a seismograph. The Richter scale provides an accurate measure for small, nearby earthquakes. But this scale does not work well for large or distant earthquakes. Moment Magnitude Scale-used today. The scale can be used to rate earthquakes of all sizes, near or far. Earthquakes with a magnitude below 5.0 on the moment magnitude scale are small and cause little damage. Earthquakes with a magnitude above 5.0 can produce great destruction. Earthquakes with a magnitude of 6.0 release 32 times as much energy as a magnitude 5.0 quake, and as nearly 1,000 times as much as a magnitude 4.0 quake. Moment Magnitude Is the measure of total energy released by an earthquake. Moment magnitude is the measurement and term generally prefered by scientists and seismologists to the Richter scale because moment magnitude is more precise. Moment Magnitude is not based on instrumental recordings of a quake, but on the area of the fault that ruptured in the quake. Moment Magnitude is calculated in part by multiplying the area of the fault's rupture surface by the distance the earth moves along the fault Richter and Moment Magnitude Scale http://quake.ualr.edu/public/moment.htm Locating the Epicenter Geologists use seismic waves to locate an earthquake’s epicenter. Seismic waves travel at different speeds. P waves arrive first at a seismograph, with S waves following close behind. To tell how far the epicenter is from the seismograph, scientists measure the difference between the P waves and the S waves. The farther away an earthquake is, the greater the time difference between the arrival of the P waves and S waves. Geologists draw at least three circles using data from different seismographs set up at stations all over the world. Ch 2, sect. 3 Earthquake Hazards and Safety How Earthquakes Cause Damage When a major earthquake strikes, it can cause great damage. The severe shaking produced by seismic waves can damage or destroy buildings and bridges, topple utility poles, and fracture gas and water mains. Local Soil Conditions- When seismic waves move from hard, dense rock to loosely packed soil, they transmit their energy to the soil causing the soil to shake more violently than its surroundings. Liquefaction- Occurs when earthquake’s violent shaking suddenly turns loose, soft soil into liquid mud. Aftershocks – an earthquake that occurs after a larger earthquake in the same area. Aftershocks may strike hours, days, or even months later. Tsunamis-When an earthquake jolts the ocean floor, plate movement causes the ocean floor to rise slightly and push water out of its way. If the earthquake is strong enough, the water displaced by the quake forms large waves, called Tsunamis. Choice of Location- The location of the building affects the type of damage it may suffer during an earthquake. Steep slopes pose the danger of landslides Filled land can shake violently Making Buildings Safer To reduce damage, new buildings must be made stronger and more flexible. Older buildings must be modified to withstand stronger quakes. Construction Methods The way a building is constructed determines whether it can withstand an earthquake. During an earthquake, brick buildings as well as some wood frame buildings may collapse if their walls have not been reinforced. Base-isolated buildings- a building designed to reduce the amount of energy that reaches a building Protecting Yourself during an Earthquake The main danger is from falling objects and flying glass. The best way to protect yourself is to drop, cover, and hold. (crouch beneath a sturdy table or desk and hold on to it so it doesn’t jiggle away during the shaking. If no desk is available, crouch against an inner wall, away from the outside of a building, and cover your head and neck with your arms. If you are outdoors, move to an open area such as a playground. Avoid power lines, trees, and buildings, especially ones with brick walls or chimneys. Sit down to avoid being thrown. After a major earthquake, water and power supplies may fail, food stores may be closed, and travel may be difficult. Ch 2, sect. 1 Earth’s Crust in Motion Stress in the Crust An earthquake is the shaking and trembling that results from the movement of rock beneath earth’s surface. The movement of Earth’s plates create powerful forces that squeeze or pull the rock in the crust- these are examples of stress. Stress-a force that acts on a rock to change its shape or volume. Types of stress: Shearing, Tension, and Compression Shearing: Stress that pushes a mass of rock in two opposite directions. Tension: Stress that pulls on the crust, stretching rock so that it becomes thinner in the middle. Compression: Stress that squeezes rock until it folds or breaks. Any change in the volume or shape of Earth’s crust is called deformation. Kinds of Faults A fault is a break in the Earth’s crust where slabs of crust slip past each other. Faults usually occurs along plate boundaries, where the forces of plate motion compress, pull, or shear the crust so much that the crust breaks. Strike-Slip Faults- created by shearing. The rocks on either side of the fault slip past each other side ways with little up or down motion. A strike slip fault that forms the boundary between two plates is called a transform boundary. Normal faults- tension forces in the crust cause normal faults. In a normal fault, the fault is at an angle, so one block of rock lies above the fault while the other block lies below the fault. Hanging wall- Footwall- When movement occurs along a normal fault, the hanging wall slips downward. Reverse Faults- Compression forces produce reverse faults. The fault has the same structure as a normal fault, but the blocks move in opposite direction. Skipping Friction Along Faults and Mountain Building Normal Fault picture Reverse Fault Picture Ch 2, sect. 2 Measuring Earthquakes An earthquake starts at one particular point. The focus is the point beneath Earth’s surface where the rock that is under the stress breaks, triggering an earthquake. The point on the surface directly Seismic Waves are vibrations that travel through Earth carrying energy released during an earthquake. The seismic waves move like ripples in a pond. Seismic waves carry the energy of an earthquake away from the focus, through Earth’s interior, and across the surface. Three categories of seismic waves: P waves, S waves, Surface waves. P waves- Primary waves. The first to arrive. Earthquake waves that compress and expand the ground like an accordion. Travels through solids and liquids S waves- Secondary waves Earthquake waves that vibrate side to side as well as up and down When they reach the surface, they shake structures violently. Travels through solids not liquids Surface Waves When P and S waves reach the surface, some are transformed into surface waves. These move more slowly than P and S waves These produce severe ground movements. Measuring Earthquakes Three ways of measuring earthquakes: Mercalli scale, the Richer scale, the moment magnitude scale. Mercalli scale-developed in the early 20th century. Developed to rate earthquakes according to their intensity. Richter scale-rating the size of seismic waves as measured by a seismograph. The Richter scale provides an accurate measure for small, nearby earthquakes. But this scale does not work well for large or distant earthquakes. Moment Magnitude Scale-used today. The scale can be used to rate earthquakes of all sizes, near or far. Earthquakes with a magnitude below 5.0 on the moment magnitude scale are small and cause little damage. Earthquakes with a magnitude above 5.0 can produce great destruction. Earthquakes with a magnitude of 6.0 release 32 times as much energy as a magnitude 5.0 quake, and as nearly 1,000 times as much as a magnitude 4.0 quake. Locating the Epicenter Geologists use seismic waves to locate an earthquake’s epicenter. Seismic waves travel at different speeds. P waves arrive first at a seismograph, with S waves following close behind. To tell how far the epicenter is from the seismograph, scientists measure the difference between the P waves and the S waves. The farther away an earthquake is, the greater the time difference between the arrival of the P waves and S waves. Geologists draw at least three circles using data from different seismographs set up at stations all over the world. Ch 2, sect. 3 Earthquake Hazards and Safety How Earthquakes Cause Damage When a major earthquake strikes, it can cause great damage. The severe shaking produced by seismic waves can damage or destroy buildings and bridges, topple utility poles, and fracture gas and water mains. Local Soil Conditions- When seismic waves move from hard, dense rock to loosely packed soil, they transmit their energy to the soil causing the soil to shake more violently than its surroundings. Liquefaction- Occurs when earthquake’s violent shaking suddenly turns loose, soft soil into liquid mud. Liquefaction is likely to occur when an earthquake’s violent shaking suddenly turns loose. Aftershocks – an earthquake that occurs after a larger earthquake in the same area. Aftershocks may strike hours, days, or even months later. Tsunamis-When an earthquake jolts the ocean floor, plate movement causes the ocean floor to rise slightly and push water out of its way. If the earthquake is strong enough, the water displaced by the quake forms large waves, called Tsunamis. Making Buildings Safer To reduce damage, new buildings must be made stronger and more flexible. Older buildings must be modified to withstand stronger quakes. Choice of Location- The location of the building affects the type of damage it may suffer during an earthquake. Steep slopes pose the danger of landslides Filled land can shake violently Construction Methods The way a building is constructed determines whether it can withstand an earthquake. During an earthquake, brick buildings as well as some wood frame buildings may collapse if their walls have not been reinforced. Base-isolated buildings- a building designed to reduce the amount of energy that reduces the amount of energy that reaches a building Protecting Yourself during an Earthquake The main danger is from falling objects and flying glass. The best way to protect yourself is to drop, cover, and hold. (crouch beneath a sturdy table or desk and hold on to it so it doesn’t jiggle away during the shaking. If no desk is available, crouch against an inner wall, away from the outside of a building, and cover your head and neck with your arms. If you are outdoors, move to an open area such as a playground. Avoid power lines, trees, and buildings, especially ones with brick walls or chimneys. Sit down to avid being thrown. After a major earthquake, water and power supplies may fail, food stores may be closed, and travel may be difficult. Ch 2, sect. 4 Section 4 Monitoring Faults Story- In the early 1980’s, geologists predicted that a strong earthquake was going to occur in Parkfield between 19851993. Geologists waited for the predicted earthquake, but it never came. Finally, medium-sized earthquakes rumbled along the San Andreas fault near Parkfield in 19931994. What went wrong? Geologists don’t know, but they continue to monitor the San Andreas fault. Someday they may find a way to predict when and where an earthquake will occur. Devices that Monitor Faults- To observe these changes in ground movement, geologists put in place instruments that measure stress and deformation in the crust. * Creep Meters-uses a wire stretched across a fault to measure horizontal movement of the ground. Geologists can measure the amount that the fault has by measuring how much the weight has moved against a measuring scale. * Laser-Ranging Devices- Uses a laser beam to detect even the tiny fault movements. The device calculates any change in the time needed for the laser beam to travel to a reflector and bounce back. * Tiltmeters-measure the tilting of the ground. Consists of two bulbs that are filled with a liquid and connected by a hollow stem. * Satellite Monitors- Besides ground based instruments, geologists use satellites equipped with radar to make images of faults. The satellite bounces radio waves off the ground. As the waves echo back into space, the satellite records them. Monitoring Risk in the United States Even with data from many sources, geologists can not predict when and where a quake will start. Geologists do know that earthquakes are likely wherever plate movement stores energy in the rock along faults. Geologists can determine earthquake risk by locating where faults are active and where past earthquakes have occurred. In the United States, the risk is highest along the Pacific coast where the Pacific and North American plates meet - California, Washington, and Alaska. Other regions of the United States also have some risk of earthquakes – rare east of the Rockies. Chapter 3 Volcanoes Section 1: Volcanoes and Plate Tectonics What is a Volcano? A volcano is a weak spot in the crust where molten material, or magma, comes to the surface. Magma is a molten mixture of rock-forming substances, gases, and water from the mantle. When magma reaches the surface, it is called lava. After lava has cooled, it forms solid rock. Location of Volcanoes There are about 600 active volcanoes on land. More lie beneath the sea. Volcanoes occur in belts that extend across continents and oceans. The Ring of Fire is one major volcanic belt formed by the many volcanoes that rim the Pacific Ocean. Most volcanoes occur along divergent plate boundaries, such as the mid-ocean ridge, or in subduction zones around the edges of oceans. Volcanoes at Diverging Plate Boundaries Volcanoes form along the m id-ocean ridge, which marks a diverging plate boundary. Along the ridge, lava pours out of the cracks in the ocean floor. Volcanoes at Converging Boundaries Many volcanoes form near plate boundaries where oceanic crust returns to the mantle. Subduction causes slabs of ocean crust to sink through a deep ocean trench into the mantle. Island Arc- a string of volcanoes formed by the volcanoes along a deep ocean trench. Hot Spot Volcanoes A hot spot is an area where magma from deep within the mantle melts through the crust like a blow torch. Hot spots often lie in the middle of continental or oceanic plates far from any plate boundaries. A hot spot volcano in the ocean floor can gradually form a series of volcanic mountains. Chapter 3 Volcanoes Section 2: Volcanic Activity How Magma Reaches Earth’s Surface Lava begins as magma in the mantle. It rises until it reaches the surface, or becomes trapped beneath layers of rock. A Volcano Erupts As magma rises to the surface, the pressure decreases. The dissolved gases begin to separate out, forming bubbles. During a volcanic eruption, the gases dissolved in magma rush out, carrying the magma with them. Inside a Volcano Beneath a volcano, magma collects in a pocket called a magma chamber. The magma moves through a pipe, a long tube in the ground that connects the chamber to Earth’s surface. Molten rock and gas leave the volcano through an opening called a vent (side vents). A lava flow is the area covered by lava as it pours out of a vent. A crater is a bowl-shaped area that may form at the top of a volcano around the volcano’s central vent. Inside a Volcano magma chamber pipe vent (side vents) lava flow crater Characteristics of Magma The force of a volcanic eruption depends partly on the amount of gas dissolved in the magma. Additionally, how thick or thin the magma is, its temperature, and its silica content are also important factors. Magma’s temperature partly determines how thick of fluid is. The more silica, formed from the elements of silicon and oxygen, the thicker the magma is. Magma that is high in silica produces light colored lava that is too sticky flow very far. This cools and forms Rhyolite. Other formations: Pumice (formed in high silica) when gas bubbles are trapped in cooling lava, leaving spaces in the rock. Obsidian (formed in high silica) when lava cools very quickly, giving it a smooth, glossy surface. Magma that is low in silica flows steadily and produces dark colored lava. (Example- Basalt) Types of Volcanic Eruptions The silica content of magma helps to determine whether the volcanic eruption is quiet or explosive. Quiet Eruptions- A volcano erupts quietly as its magma flows easily. Quiet eruptions produce two types of lava: Pahoehoe and aa. Pahoehoe- fast moving, hot lava. Surface looks like a solid mass of wrinkles, billows, and ropelike coils. aa.-forms a rough surface consisting of jagged lava chunks. Explosive Eruptions A volcano erupts explosively if its magma is thick and sticky. Thick magma does not flow out of the crater and down the mountain. Instead, it slowly builds up in the volcano’s pipe, plugging it like a cork in a bottle. Dissolved gases get trapped and build up under pressure until they explode. Pyroclastic flow occurs when an explosive eruption hurls out ash (fine rocky particles), cinders (pebble sized particles), and bombs (larger pieces) as well as gases. Stages of a Volcano Active – or “live volcano,” is one that is erupting or has shown signs that it may erupt in the near future. Dormant – or “sleeping,” is expected to awaken in the future and become active. Extinct – “or dead,” is unlikely to erupt again. Other Types of Volcanic Activity Hot spring- forms when the ground water heated by a nearby body of water of magma rises to the surface and collects in a natural pool.. Sometimes, rising hot water and stream become trapped underground in a narrow crack. Pressure builds up until the mixture suddenly sprays above the surface as a geyser. In volcanic areas, water heated by magma can provide a clean, reliable energy source called geothermal energy Monitoring Volcanoes Geologists have been somewhat more successful in predicting volcanic eruptions than in predicting earthquakes. Changes in and around a volcano usually give warning a short time before it erupts. Volcano Hazards Although quiet eruptions and explosive eruptions involve different volcano hazards, both types of eruption can cause damage far from the crater’s rim. Lava can flow from vents setting materials on fire. Volcanic ash can bury entire towns, damage crops, and clog car engines. Heavy ash can cause roofs to collapse. Eruptions can cause landslides and avalanches of mud, melted snow, and rock. Chapter 3 Volcanoes Section 3: Volcanic Landforms Landforms from Lava and Ash Rock and other materials formed from lava create a variety of landforms including shield volcanoes, composite volcanoes, cinder cone volcanoes, and lava plateaus. Shield volcanoes – created when thin layers of lava pour out of a vent and harden on top of previous layers. Cinder Cone Volcanoes – steep, cone shaped, may produce ash, cinders, and bombs. Composite Volcanoes – tall, cone shaped mountains with alternating layers of ash Lava Plateaus – instead of forming mountains, eruptions may form high level areas called plateaus. Lava flows out of several cracks along the area and cool and solidify. Calderas – enormous eruptions may empty vent or chamber and the huge hole that remains is a caldera. Soils from Lava and Ash Once the hard surface of lava breaks down, the soil is rich and can support plant growth. Volcanic ash also breaks down and releases phosphorous and other materials that plants need. Landforms from Magma Sometimes magma forces its way through cracks in the upper crust, but fails to reach the surface. Features formed by magma include volcanic necks, dikes, and sills, as well as batholiths and dome mountains. Volcanic necks – forms when magma hardens in a volcano’s pipe. Dikes – forms when magma forces itself between rock layers and hardens Sills – forms when magma forces itself between layers of rock. Batholiths – large rock masses that form when a large body of magma cools inside of the crust. Dome Mountains-forms when rising magma is blocked by horizontal layers of rock causing the layers of rock to bend upward into a dome shape. Chapter 4 Minerals Section 1:Properties of Minerals Properties of Minerals What is a Mineral? A mineral is a naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition. For a substance to be a mineral, it must have all five of these characteristics. Naturally Occurring – must occur naturally in nature. Cement, brick, steel, and glass all come from substance found in the earth’s crust, but these materials are manufactured by people. Inorganic-the mineral can not arise from material that was once part of a living thing. Solid-always a solid with a definite volume and shape. Crystal Structure-particles of a mineral line up in a pattern that repeats over and over again. The repeating pattern of a mineral’s particles forms a solid called a crystal. Definite Chemical Composition – the mineral always contains certain elements in definite proportions. An element is a substance composed of a single kind of atom. All atoms of the same element have the same chemical and physical properties. Identifying Minerals Because there are so many different kinds of minerals, telling them apart can be challenging. The color of a mineral alone provides too little information to make an identification. Each mineral has its own specific properties that can be used to identify it. Hardness test- Mohs hardness scale – this scale ranks ten minerals from softest to hardest. Color – the color of a mineral is an easily observed physical property. Streak – a streak test can provide a clue to a mineral’s identity. The streak of a mineral is the color of its powder. Luster – the term used to describe how a mineral reflects light from its surface. For example, terms to describe luster are shiny, metallic, earthy, waxy, and pearly. Density – (mass in a given space). No matter what the size of a mineral sample, the density of that mineral always remains the same. Crystal Systems – the crystals of each mineral grow atom by atom to form that minerals’ particular crystal structure. There are several different groups or crystal systems. (6 are described in your text). Cleavage and Fracture The way a mineral breaks apart can help to identify it. A mineral that splits easily along flat surfaces has the property called cleavage. A mineral that breaks apart in an irregular way is called fracture. Special Properties- Some minerals have special properties: fluorescent, magnetic, radioactive, chemically reactive, or electrical properties. Chapter 4 Minerals Section 2: How Minerals are Formed Process that Form Minerals In general, minerals can form in two ways: through crystallization of melted materials, and through crystallization of materials dissolved in water. Minerals From Magma Minerals form as hot magma cools inside the crust, or as lava hardens on the surface. When magma remains deep below the surface, it cools slowly over months and years. Slow cooling leads to the formation of large crystals. Magma closer to the surface cools much faster than magma that hardens deep below the ground. With more rapid cooling, there is no time for magma to form large crystals. Minerals From Hot Water Solutions – A solution is a mixture in which one substance dissolves in another. Pure metals that crystallize underground from hot water solutions form veins. A vein is a narrow channel or slab of a mineral that is much different from the surrounding rock. Many minerals form from solutions at places where tectonic plates spread apart at mid ocean ridges. First, ocean water seeps down through the cracks in the crust. There, the water comes in contact with magma that heats it to a very high temperature. The heated water dissolves minerals from the crust and rushes upward. The hot water billows out of vents, called “chimneys”. When the hot solution hits the cold sea, minerals crystallize and settle to the ocean floor. Minerals Formed by Evaporation Minerals can from when solutions evaporate. In the same way, thick deposits of mineral halite formed over millions of years when ancient seas slowly evaporated. Other minerals that come from the evaporation of sea water are gypsum, calcite crystals, and minerals containing potassium. Where Minerals Are Found Earth’s crust is made mostly of the common rock forming minerals combined in various rock. Less common and rare minerals, however are not distributed evenly throughout the crust Chapter 5 Rocks Section 1 Classifying Rocks Chapter 5 Rocks Section 1 Classifying Rocks How Geologists Classify Rocks Rocks are made of mixtures of minerals and other materials, although some rocks may contain only a single mineral. Geologists collect and study samples of rocks in order to classify them. When studying a rock’s sample, geologists observe the rocks’ color and texture and determine its mineral composition. Texture A rock’s texture is the look and feel of the rock’s surface. Some rocks are smooth and glassy. Others are rough and chalky. Most rocks are made of particles or other rocks, which geologists call grains. Grain Size – the grains may be large and easy to see (coarse grain) or so small that they can only be seen with a microscope (fine grained). Grain shape – the grains in rocks vary widely in shape. Some look like tiny particles of fine sand while others look like seeds or exploding stars. Grain shape results from fragments of other rock. These fragments can be smooth. Grain pattern – the grains in rocks often form patterns. Some lie in flat layers that look like a stack of pancakes. Others form wavy, swirling patterns or look like multicolored beads. Grains can also be random. No visible grain – these rocks cool very quickly giving the rock a smooth shiny texture. Other rocks with no visible grain are made up of extremely small particles that settle out of water. Mineral Composition – Geologists can test for the minerals that make up the rocks. Origin – There are three major groups of rocks: igneous, sedimentary rock, and metamorphic rock. Igneous – forms from the cooling of molten rock. Sedimentary – forms when particles of other rocks or the remains of plants and animals are pressed and cemented together. Metamorphic – formed when an existing rock is changed by heat, pressure, or chemical reactions. Chapter 5 and Your Understanding of Rocks Get your lab notebook. Turn to page 150 in your text book. Place tables together for groups. Read instructions Begin-Follow instructions as you work through the lab. Chapter 1: Motion Section 1: Describing and Measuring Motion Describing Motion-An object is in motion if its distance from another object is changing. Reference Points-To decide if you are moving, use a reference point. A reference point is a place or object used for comparison to determine if something changes position relative to its reference point. Objects that are stationary-such as a tree, a sign, or a building-make good reference point. Relative Motion – Whether or not an object is in motion depends on the reference point or the reference that you choose. For example, are you moving as you read this book? To answer that question depends on your reference point. When your chair is your reference point, you are not moving. But if you choose another reference point, you are moving. Sun example – if you choose the sun as a reference point, you are moving quite rapidly because you chair is on the earth and the earth moves about 30 km every second. Measuring Distances – You use units of measurements to describe motion precisely. (Standard quantities of measurement). Scientists all over the world use the same system of measurements - International System of Units. When describing motion, scientists use SI units to describe the distance an object moves. When you measure distance, you measure length. The SI unit of length is 1 meter. The length of an object smaller than a meter is called the centimeter. Calculating Speed – A measurement of distance can tell you how far an object travels. If you know the distance an object travels in a certain amount of time, you can calculate the speed of an object. The speed of an object is the distance the object travels per unit of time. The speed equation: Speed = Distance/Time Average Speed: The speed of most moving objects is not constant: The average speed equation: Total Distance/Total Time Instantaneous Speed: The rate at which an object is moving at a given instant in time. Describing Velocity – Knowing the speed at which something travels does not tell you everything in motion. To describe the objects motion completely, you need to know both the speed and direction of an object’s motion. Velocity- speed in a given direction. Graphing Motion. You can show the motion of an object on a line graph in which you plot distance versus time. Time is shown on a horizontal, or x axis. Distance is shown on the vertical, or y axis. The steepness of a line on a graph is called slope. The slope tells you how fast one variable changes in relation to the other variable in the graph. Calculating Slope: You can calculate the slope of a line by dividing the rise by the run. Different Slopes – Moving objects do not travel at a constant speed. See line graph that is divided into 3 segments (pg.15) Speed Challenge Demonstration Chapter 1: Motion Section 2: Acceleration What is Acceleration? In science, acceleration refers to increasing speed, decreasing speed, or changing direction. Increasing Speed-When an object’s speed increases, the object accelerates. Decreasing Speed-When an object’s speed decreases, the change is speed is sometimes called acceleration or deceleration. Changing Direction – recall that an object can be in a change of direction as well as a change in speed. Therefore a car accelerates as it follows a curve in a track. Many objects continuously change direction without changing speed. The simplest example of this motion is along a circular path. Calculating Acceleration Acceleration describes the rate at which velocity changes. If an object is not changing direction, you can describe its acceleration as the rate at which its speed changes. To determine acceleration of an object moving in a straight line, you must calculate the change in speed per unit of time. Acceleration: (Final speed-Initial speed)/Time Write the following problems in your notes. Solve them. Suppose a sprinter's velocity changes from 0 m/s to 10 m/s in 2 seconds at the start of a race. What is her acceleration? 1. Write formula 2. Fill in information. 3. Keep units 4. Cancel out 5. Write answer. A car starts from rest and accelerates at 2 m/s/s for 5 seconds. How fast will it be going? 1. Write formula 2. Fill in information. 3. Keep units 4. Cancel out 5. Write answer. A car's velocity changes from +2 m/s to +10 m/s in 4 seconds. What is its acceleration? 1. Write formula 2. Fill in information. 3. Keep units 4. Cancel out 5. Write answer. A car's velocity changes from +10 m/s to +2 m/s in 4 seconds. What is its acceleration? 1. Write formula 2. Fill in information. 3. Keep units 4. Cancel out 5. Write answer. Graphing Acceleration: You can use both a speed-versus-time graph and a distanceversus-time graph to analyze the motion of an accelerating object. Speed-versus-time graph-The slant of the speed versus time graph tells you how the object is accelerating. The slope of the speed versus time graph tells you the object’s acceleration. Speed-versus-time graph Distance-versus-time graph- You can represent the motion of an accelerating object with a distance-versus time graph. See figure 12 on pg. 12 - The curved line means that the object is accelerating. The curved line also tells you that during each second the speed is greater than the second before. From second to second the slope gets steeper. Since the slope is increasing, you can conclude that the speed is also increasing- the object is accelerating. Distance-versus-time graph- Which object has a faster speed? How do you know? What does this graph tell you about acceleration? Chapter 2: Forces Section 1: The Nature of Force What is a Force? In science, a force is a push or a pull. When one object pushes or pulls another object, you say that the first object exerts a force on the second object. Like velocity and acceleration, a force is described by its strength and by the direction in which it acts. The strength of a force is measured in the SI unit called Newton (N). You exert about one Newton of force when you lift a small lemon. Combining Forces Often, more than a single force acts on an object at one time. The combination of all forces acting on an object is called the net force. The net force determines whether an object moves and also in which the direction it moves. Forces can act in the same direction or in opposite directions. Unbalanced Forces When there is a net force acting on an object, the forces are unbalanced. Unbalanced forces can cause an object to start moving, stop moving, or change direction. Unbalanced forces acting on an object result in a net force and cause a change in the object’s motion. http://scienceclass.net/Physics/Force_Motion/forces_wsREG_V2.pdf Balanced Forces When forces are exerted on an object, the object’s motion does not always change. Balanced forces acting on an object do not change the object’s motion. Equal forces acting on one object in opposite directions are called balanced forces. Practice with Balancing Forces Chapter 2: Forces Section 2: Friction and Gravity Friction is the force that two surfaces exert on each other when they rub against each other. The Causes of Friction The strength of the force of friction depends on two factors: how hard the surfaces push together and the types of surfaces involved. Static Friction. The friction that acts on objects that are not moving is called static friction. Sliding Friction. Occurs when two solid surfaces slide over each other. Rolling Friction. When an object rolls across a surface, rolling friction occurs. Fluid Friction. Fluids such as water, oil, or air, are materials that flow easily. Fluid friction occurs when a solid object moves through a fluid. Go over Free Body Diagrams Gravity Gravity is a force that pulls objects toward each other. The law of Universal Gravitation This law states that the force of gravity acts between all objects in the universe. This means that any two objects in the universe attract each other. Factors Affecting Gravity Two factors affect the gravitational attraction between objects: mass and distance. -Mass is a measure of the amount of matter in an object. SI unit for mass is kilogram. The more mass an object has, the greater the gravitational force. Weight and Mass Mass is sometimes confused with weight. Mass is a measure of the amount of matter in an object; weight is a measure of the gravitational force exerted on an object. Weight varies with the strength of the gravitational force but mass does not. Gravity and Motion On earth, gravity is a downward force that affects all objects. Free Fall When the only force acting on an object is gravity, the object is said to be in free fall. An object in free fall is accelerating. Why?-In free fall, the force of gravity is an unbalanced force, which causes an object to accelerate. Near earth’s surface, the acceleration due to gravity is 9.8m/s2. This means that for every second an object is falling, its velocity increases by 9.8m/s. Air Resistance Despite the fact that all objects are supposed to fall at the same rate, you know that this is not always the case. Objects falling through the air experience a type of fluid friction called air resistance. *Remember that friction is the direction opposite to motion, so air resistance is an upward force exerted on falling objects. Air Resistance is not the same for all objects. Falling objects with greater surface area experience more air resistance Air resistance increases with velocity. As a falling object speeds up, the force of air resistance becomes greater and greater. Eventually, a falling object will fall fast enough that the upward force of air resistance becomes equal to the downward force of gravity acting on the object. At this point the forces on the object are balanced. The object continues to fall, but its velocity remained constant. The greatest velocity a falling object reaches is called its terminal velocity. Projectile Motion An object that is thrown is called a projectile. Will a projectile that is thrown horizontally land on the ground at the same time as an object that is dropped? Answer –Yes. Even though one ball moves horizontally, the force of gravity is acting on both balls and will hit the ground at the same time. 5-18-10 Science Notes: Ch. 2, section 3 and 4 Newton’s Laws The First Law of Motion Newton’s first law of motion states that an object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force. Inertia The tendency of an object to resist a change in motion. Inertia explains many common events, such as why you move forward in your seat when a car stops suddenly. When the car stops, inertia keeps you moving forward. Inertia Depends on Mass Some objects have more inertia than other objects. The greater the mass of an object, the greater the inertia, and the greater the force required to change motion. Example: Suppose you needed to move an empty aquarium and an aquarium full of water. Which on is harder to move and why? The full aquarium is harder to move because it has more mass. The greater the mass of an object, the greater the force required to change its motion. The full aquarium is more difficult to move because it has more inertia than the empty inertia. The Second Law of Motion According to Newton’s second law of motion, acceleration depends on the object’s mass on the net force acting on the object. This relationship is written as an equation: Acceleration = Net force/Mass Acceleration is measured in meters per second per second. Force is measured in kilograms times meters per second per second (kg * m/s2). The short form for this is Newton (N). (1 Newton as the force required to give a 1kg mass an acceleration on 1 m/s2 . Changes in Force and Mass How can you increase the acceleration of an object? *One way is to change the force-increase the force (keeping the mass the same) *Another way is to change the mass – decrease the mass (keeping the force the same) Chapter 2 Forces Section 4: Newton’s Third Law Newton’s third law of motion states that if one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. Action-Reaction Pairs When the gymnast does a flip, he pushes down on the vaulting horse. The reaction force of the vaulting horse pushes him up to complete the flip. When the dog leaps, it pushes down on the ground. The reaction force of the ground pushes the dog in the air. The kayaker’s paddle pulls on the water. The reaction force of the water pushes back on the paddle, causing the kayak to move. . Do Action-Reaction Forces Cancel? Earlier we learned that if two equal forces act in opposite directions on an object, the forces are balanced. Because the two forces add up to zero, they cancel each other out and produce no change in motion. Why don’t action and reaction forces cancel each other out? It is because they are acting on different objects 5-24-10 Science Notes: Ch. 4, section 1 What is Work? The Meaning of Work: In SCIENTIFIC terms Work is done on an object when the object moves in the same direction in which the force is exerted. Example – If you push a child on a swing, you are doing work on the child. No Work without Motion: To do work, the object must move a distance as a result of your force. If you exert a force on an object but the object does not move, you are not doing work. Force in the Same Direction Remember-to do work on an object, the force must be in the same direction as the objects motion. Returning to the example of work when lifting and carrying a back pack. You are not doing work when you are carrying your bag pack. You only did work when you lifted your back pack Calculating Work The amount of work done on an object can be determined by multiplying force times the distance. Work = Force * Distance When force is measured in newtons and distance in meters, the SI unit of work is the Newton * meter (N*m) – this unit is called a joule. One joule (J) is the amount of work you do when you exert a force of 1 newton to move an object a distance of 1 meter. Power: The amount of work you do on an object is not affected by the time it takes to do the work. For example, if you carry a backpack up a flight of stairs, the work you do is the weight of the backpack times the height of the stairs. (Work = Force * Distance) Time is important when we talk about power. Power is the rate at which work is done. Power equals that amount of work done on an object in a unit of time. Calculating Power Power = Work/Time Or Power = Force * Distance Time Power Units: When work is measured in joules and time in seconds, the SI unit of power in the joule per second (J/s). 5-26-10 Science Notes: Ch. 4, section 2 How Machines Do Work What is a Machine? A machine is a device that allows you to do work in a way that is easier. A machine makes work easier by changing at least one of three factors. A machine may change the amount of force you exert, the distance over which you exert your force, or the direction in which you exert your force. Input and Output Work The input force times the input distance is called the input work. The output force times the output distance is called the output work. Changing Force: In some machines, the output force is greater than the input force. Remember the formula for work is Force * Distance, therefore if the amount of work stays the same, a decrease in force must mean an increase in distance. (example- pushing a box up a ramp instead of lifting it onto a stageyou exert less force over a greater distance when pushing the box up the ramp). Input and Output Work Changing Distance: In some machines the output force is less than the input force. In order to apply a force over a shorter distance, you need to apply a greater input force. (example- taking a shot with a hockey stick. You move your hands a short distance, but the other end of the stick moves a greater distance). Changing Direction: Some machines don’t change either force or distance. Think abut a weight machine. You could stand and lift the weights, but it is easier to sit on the machine and pull down than to lift up. Mechanical Advantage: If you compare the input force to the output force, you can find the advantage of using a machine. A machine’s mechanical advantage is the number of times a machine increases a force exerted on it. It is calculated using the following formula: Output Force Input Force Increasing Force: When the output force is greater than the input force, the mechanical advantage of a machine is greater than 1. Increasing Distance: For a machine that increases distance, the output force is less than the input force.So in this case, the mechanical advantage is less than 1. Changing Direction: If only the direction changes, the input force will be the same as the output force. The mechanical advantage will always be 1. Efficiency of Machines: In real life the output work is always less than the input work. Friction and Efficiency. In every machine, some work is wasted overcoming the force of friction. The less friction there is, the closer the output work is to the input work. The efficiency of a machine compares the output work to the input work. Efficiency is expressed as a percent. The higher the percent, the more efficient the machine is. Calculating Efficiency: To calculate the efficiency of a machine, divide the output work by the input work and multiply the result by 100%. Efficiency = Output work * 100% Input Work Real and Ideal Machines: An ideal machine has an efficiency of 100%. Unfortunately, an ideal machine does not exist. In all machines, some work is wasted due to friction. A machine’s measured mechanical advantage is called actual mechanical advantage. Chapter 4 Work and Machines Section 3: Simple Machines There are six basic kinds of simple machines: the inclined plane, the lever, the wedge, the screw, the wheel and axel, and the pulley. Inclined Plane: A flat, sloped surface. How it works: An inclined plane allows you to exert your input force over a longer distance. As a result, the input force needed is less than the output force. Input force-the force to push or pull the object on the inclined plane. Output force-the force you would need to lift the object without the inclined plane. Ideal Mechanical Advantage for an inclined plane: divide the length of the incline by its height. IMA- Length of the incline Height Wedge a device that is thick at one end and tapers to a thin edge at another end. How it works: When you use a wedge, instead of moving the object along the inclined plane, you move the incline plane itself. Ideal Mechanical Advantage for a wedge: divide the length of the wedge by its width. The longer and thinner the wedge is, the greater its mechanical advantage. IMA - length of the wedge width Screws: an inclined plane wrapped around a cylinder. How it works: example-the threads of a screw act like an inclined plane to increase the distance over which you exert the input force. As the threads of the screws turn, they exert an output force on the wood. Mechanical Advantage for a Screw: The closer together the threads of a screw are, the greater the mechanical advantage. Why? The closer the threads are, the more times you must turn the screw to fasten it in the object. The input force is applied over a longer distance. The ideal mechanical advantage of a screw is the length around the threads divided by the length of the screws. IMA- Length around the threads Length of the screws Levers a lever is a rigid bar that is free to pivot, or rotate, on a fixed point. The fixed point that a lever pivots around is called the fulcrum. How it works: (example) using a paint can opener in which the opener rests against the edge of the can. The edge of the can is the fulcrum. The tip of the opener is under the lid of the can. The ideal mechanical advantage of a lever is determined by dividing the distance from the fulcrum to the input force by the distance from the fulcrum to the output force IMA = Distance from fulcrum to input force Distance from fulcrum to output force Different Types of Levers First-Class Levers: In all first class lever the Fulcrum is between the Effort (Input Force) and Resistance (Output force) (EFR). Second Class Levers In all second class levers the Resistance (Output force) is between Fulcrum and the Effort (Input Force) (FRE). Third Class Levers In all Third class levers the Effort (Input Force) is between the Resistance (Output force) and Fulcrum (FER). Wheel and Axel A simple machine made of two circular or cylindrical objects fastened together that rotate about a common axis. The object with the larger radius is called the wheel and the object with the smaller radius is called the axle. How it works: When you use a wheel an axel, such as a screwdriver, you apply an input force to turn the handle, or wheel. Because the wheel is larger than the axel, the axel rotates and exerts a large output force. IMA = Radius of wheel Radius of axel Pulleys A simple machine made of a grooved wheel with a rope or cable wrapped around it. How it works: You use a pulley by pulling on one end of the rope. This is the input force. At the other end of the rope, the output force pulls up of the object you want to move. The ideal mechanical advantage of a pulley is equal to the number of sections of rope that support the object. Compound Machines A compound machines is a machine that utilizes two or more simple machines. The ideal advantage of a compound machine is the product of the individual ideal mechanical advantages of the simple machines that make it up.