study-notes

Science 7

I hate this.

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Scientific Method

• There are numerous steps to a scientific experiment:
  • A problem statement is a sentence in the form of a testable question. It’s mainly: “What effect does (manipulated variable) have on (responding variable)?”
  • Background knowledge is previous knowledge that relates to the experiment. It can be definitions.
  • A prediction is an educated guess of what will happen and a reason why.
  • A hypothesis is like a prediction, but requires to be tested thoroughly and is more detailed.
  • To conduct the experiment, a list of materials is needed.
  • The procedure is the step-by-step instructions to perform the experiment. They include safety precautions.
  • The conclusion is what was found out (answer and explain the problem), whether the hypothesis was proven or disproven, and sources of error that can be used for accuracy and improvements.
• The manipulated (independent) variable is the one condition that’s changed in an experiment.
• The responding (dependent) variable is what’s being measured.
• Everything that stays the same is a controlled variable. A minimum of three must be stated.
• Observations are the results recorded as data in charts, graphs, diagrams, etc.
  • Qualitative observations are made using the five senses.
  • Quantitative observations are made with numbers.
• Diagrams are drawn in pencil, placed on the left of the page, neat, and have labels on the right side with straight lines (it’s ruler time).
• Always use evidence relating to the experiment when writing about it. You should test an experiment multiple times to confirm the conclusion too.

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Interactions and Ecosystems

• All living things need food, water, a suitable habitat, and gas to exchange.
• Natural resources are the materials and products found in nature.
  • Renewable resources are energy resources that can be recycled or replaced by natural processes in less than 100 years
  • Non-renewable resources are resources that take millions of years to form.
• There are two types of “things”:
  • Biotic things are living things. (humans, plants, birds, animals, insects)
  • Abiotic things are non-living things. (air, water, soil)
• A niche is the role or characteristic activity that is undertaken by an organism in an ecosystem; one organism may fill several niches.
  • Producers are plants that use energy from the Sun to make nutrients they need to survive; includes some bacteria that transfer energy from particles.
  • Consumers are organisms that eat the food made by producers; can be either herbivores, carnivores, or omnivores.
    • A herbivore is an animal that eats only plant material. (grasshopper, beaver, moose)
    • A carnivore is an animal that eats other animals. (lynx, wolf, hawk)
    • An omnivore is an animal that eats other animals and plant material. (bear, raccoon, human)
  • A scavenger is an organism that eats dead or decaying plant or animal matter. (carrion beetle, vulture)
  • Decomposers are organisms that break down the cells of dead or waste materials and absorb their nutrients. (fungi, bacteria, some worms)
• Predation is when animals hunt other animals for food. Prey are being hunted by predators.
  • Too many predators and the prey population decreasing (competition for food, leading to decreasing predator populations), and too few predators, prey won’t have enough food for all of them since there are more of them.
• A food chain is a sequence of feeding relationships among many living organisms, as they pass on food energy.
  • A food web is a network of feeding relationships among organisms.
  • A pyramid of numbers is the number of individual organisms at each level of a food chain; the number of organisms decreases with each level higher in the food chain. (there is a greater number of organisms at the bottom of the food chain than at the top)
• Biomass is the total mass of living matter; often expressed in terms of dry weight per unit area.
• Ecology is the study of how organisms interact with each other and their environment.
  • An ecologist is a scientist who studies interactions between the abiotic and biotic parts of the environment.
• An ecosystem is all the interacting parts of a biological community and its environment.
  • A population is a group of organisms of the same species found in a particular geographic area.
  • A community is an association of different populations of organisms in a particular environment or geographic area.
  • Symbiosis is when two species live closely in a relationship that lasts over time. There are three types.
  • Commensalism is when one benefits, and the other neither benefits nor is harmed. (birds and trees)
  • Mutualism is when both species benefit. (fish that eat bacteria off of other fish)
  • Parasitism is when one benefits and the other is harmed. Parasites live in or on a host and feed on it, but don’t want to kill it. (tapeworms, mosquitoes, leeches)
• An adaptation is an inherited characteristic that helps an organism survive and reproduce in its environment.
  • Behavioral adaptations change how an organism acts. (plants moving to follow the Sun, hibernation, migration)
  • Structural/physical adaptations involve change in an organism’s body. (blending into the environment, color changing, puffer fish, webbed feet)
• The carbon cycle is the cycle in which carbon is used and reused through the ecosystem.
• The water cycle is the continuous movement of water through the biosphere.
  • Evaporation is the process by which a liquid, such as water, changes into a gas or a vapor.
  • Condensation is the process of changing from a gas or vapor to a liquid. (clouds, fog, dew)
  • Transpiration is the process in which water that is taken in by a plant or animal evaporates from the organism.
  • Precipitation is the water (in its liquid or solid state) that falls to Earth. (rain, snow, sleet, hail)
  • Ground water is the water contained in the lithosphere or Earth’s crust.
  • Run-off is water that runs off the ground into lakes, rivers, or streams.
• Pollution is a collective term for the different types of harmful materials that are released into the environment through human activities.
  • Pollutants are substances that cause pollution.
  • Acid rain is rain that contains higher than normal levels of acid; caused by waste gases released into the atmosphere by industries and automobiles; damaging to the environment.
  • Bioaccumulation is the accumulation of pollutants in one organism.
  • Biomagnification is the movement of pollutants through levels of a food chain so that greater quantities are retained with movement up the food chain.
• An ecological footprint is a calculation of the total area of land and water needed to supply all the materials and energy a human uses, as well as absorb the waste produced.
  • Sustainability is when resources of nature are being renewed at least as quickly as they’re being used, and all wastes are able to be completely absorbed.
  • Reducing is limiting the amount of waste made. (buying less, shorter showers)
  • Reusing is using an item over again. (reusable food container, donating clothing)
  • Recycling is breaking down products and turning them into something else. (plastic bottles recycled into polar fleece, tires recycled into asphalt)
  • Recovering is when waste is converted into a usable form of energy. (cow farts)
• Succession is the process by which new species gradually replace old species in an ecosystem.
  • Primary succession is the gradual growth of organisms in an area that was previously bare.
  • Secondary succession is the gradual growth of organisms in an area that was formerly home to many species. (regeneration of burned forest)
• Bioinvasion is when a species that originally exists in a certain part of the planet is introduced into an entirely new location.
  • Biological control is a method of controlling insect pests using their natural enemies.
• Indicator species is a plant or animal species that helps indicate environmental change.
• When a species is extinct, it no longer exists.
• When it’s endangered, the species is in imminent danger of becoming extinct.
  • A threatened species is one whose numbers are declining.
• When a species is extirpated in a location, it’s extinct there, but there are others somewhere else.
• Vulnerable species have faced threats that may cause it to go extinct.
• The pioneer species of an area is the first one to occupy the area.
• A keystone species helps hold an ecosystem together.
• Limiting factors are factors that slow or stop population growth. (food, habitat, predators, water, space)

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Plants for Food and Fiber

• Plants are important since they provide all the energy for the ecosystem. They get energy directly from sunlight, and They need water, nutrients, space, warmth, and air to grow.
  • Fiber can also be derived from them. (clothing, paper, shelter)
  • They can also be used for medicine. (herbal remedies, tea, codeine, aloe vera, quinine, eucalyptus oils, aspirin, morphine)
  • Fuel can involve using plants. (wood/coal, sugar ethanol, wood methanol, biofuel)
  • Plants are good for the environment. (they produce oxygen, are part of the food web, provide shelter for animals, prevent soil erosion)
  • Plants can provide transportation and construction materials. (rubber, lubricants, wood, bamboo)
  • Plant roots absorb water/nutrients from soil, support/anchor the plant, and store food.
• Plants have different types of roots and parts:
  • Taproots are long, major roots that grow deep and have root hairs that help absorb water.
  • Fibrous roots are clumped, matted roots that grow shallow and absorb quickly.
  • Taproots are sometimes eaten as food. (carrots, beets, turnips, radishes, parsnips)
  • The xylem part of the stem carries water from the roots to the leaves.
• Stems transport water/nutrients, support the leaves, and store food.
  • The phloem part of the stem carries sugars from the leaves to the rest of the plant.
• Leafs produce food (photosynthesis), exchange gas, and allow water to exit the plant.
  • On a leave, stomata are tiny holes that exchange gas and water.
    • Transpiration is the evaporation of water from leaves through stomata (mostly on the underside of the leaf).
  • Leaves are green and change because chlorophyll (needed for photosynthesis and present in leaves) is green and breaks down into smaller molecules and eventually disappears when it becomes colder (autumn).
  • Photosynthesis is the process of plants making their food in their chloroplasts.
• Cellular respiration is when plants convert sugars to energy. This is needed for growth and reproduction.
• Osmosis is water moving from high to low concentrations across a selectively permeable membrane (filter for some particles). This occurs until the concentration is equal on both sides. (water moving from soil to roots (high to low))
• Diffusion is when particles/molecules move from high to low concentrations in water/air. (perfume, farts in a classroom)
• Plants can adapt to survive and reproduce better in its environment.
  • In dry conditions, they have large root systems (more water absorption), thick stems (store water), tiny spikes/spines (predator protection), flattened stems (face away from Sun to preserve water), and needles, waxy resin coat (decrease water loss).
  • In humid/tropical settings, there are usually tall stems to reach sunlight and big wide leaves to collect the Sun’s energy.
  • Seeds can be dispersed by being sticky or tasty (animals), or being shaped in a way so that they can fly away.
  • Plants can defend themselves by having a terrible smell, looking bad, moving in ways, and even eating insects.
  • Flowers also have brightly colored petals to attract pollinators, and sunflowers rotate to the Sun.
• Soil is important because it stores nutrients, air, and water, has a natural community, and allows plants to attach their roots to.
  • Soil is made of mineral particles (parent material) which are broken down rock or clay to make space for water and organic matter (humus) which is decomposed living things providing nutrients and holds water.
  • Sandy soil doesn’t hold water, is light brown, consists of mostly mineral particles, and has very little humus.
  • Clay soil holds water well (air can’t easily penetrate), forms a tight ball when wet, is hard when dry, has lots of mineral particles, and has little humus.
  • Loam soil forms a loose ball when wet, has a balance of organic and mineral particles, absorbs water well, and is great for growing most plants
  • Soil can be enhanced by adding nutrients to it through organic ways (manure compost) or chemical ways (fertilizer).
• Farming back then involved swathers which cut grain and forms them into a windrow (row of dry, cut grain), threshening which is separating grain from inedible parts, reaping is cutting the stalk for harvest with a scythe, sickle, or reaper, and winnowing which is throwing a mixture into the air as the wind blows the straw away.
• Modern tools include:
  • A combine is a machine that combines reaping, threshing, and bundling into one process (costs around $333,000 to $500,000).
  • A plow cultivates, turns, and mixes the soil to kill weeds, aid decomposition, and create space, but damages the soil. A seed drill positions seeds in the soil and then covers them.
• Ways of farming include:
  • Zero-tillage is the practice of leaving the stubble of the previous crop to prevent the soil from wind and water erosion.
  • Shelterbelts are rows of trees along edges of fields grown to reduce wind damage to crops and soil.
  • Irrigation is done by pipes and sprinklers that add moisture to soil. They’re provided with water from lakes and rivers.
  • Greenhouses are glass buildings that have plants grown in them. They let sunlight in but stop heat from escaping, so that conditions can be controlled, and better plants be grown.
  • Hydroponics is growing plants without soil. Nutrients are instead added to water and grown with just that.
  • Monoculture is planting only one crop in a field, so that it’s easier to harvest, but pests can wipe it out easier.
  • Poly culture is multiple crops in the same field, so that it’s harder for pests to wipe out, but it’s more time-consuming to harvest.
  • Crop rotation is planting different crops in a field every year. They rotate based on nutrient needs. Planting only one plant would make the soil run out of nutrients.
• Pests are weeds, insects, fungi, and introduced species that affect our ability to produce food and fiber.
  • They can be controlled through crop rotation, by machines, being chased/scared away (scarecrow), or being picked off by hand.
  • Biological control is using a pest’s natural predator to control it. (aphids and ladybugs)
  • Companion planting is growing different plants together. One discourages pests to protect the other. (rabbits and marigolds)
  • They can be controlled with herbicides (chemicals that kill plants), and pesticides (chemicals that kill insects).
  • However, if pests don’t die to pesticide, they become naturally resistant to it and pass that trait to the next generation.
  • It can kill species that weren’t intended to be harmed, get into water supplies and lakes, form resistant species, and make soil less fertile.
• An invasive species is one that doesn’t naturally belong in an area. They have no natural predator or environmental control.
• Organic farming is farming without the use of chemicals.
• Once a plant has been pollinated, a seed is formed.
  • A seed contains an embryo (plant inside seed), cotyledon (food reserve), seed coat (protects the seed), and fruit (ovary of the plant that swells to protect developing seeds).
• There are two ways for reproduction in plants (and animals):
  • Asexual (vegetative) reproduction is grown from roots, stems, or leaves of the parent, and the new plant is identical to the parent.
    • Vegetative reproduction can be done from stems through runners (long stems that grow along the soil’s surface), tubers/bulbs (underground stems), or rhizomes (long stems growing underground horizontally).
    • Vegetative reproduction can also be done from roots through suckers (new plants grow off roots of the parent plant).
    • A cutting is part of a plant’s stem and leaves cut off and replanted to maybe produce new roots (still vegetative).
  • Sexual reproduction is seeds and fruits produced from reproductive cells, and the new plant is a mix of parents.
    • During reproduction, pollen lands on the stigma, a pollen tube grows down the style to the ovary (pollination), the pollen and egg join (fertilization), and a seed is created.
• A flower has male and female parts too:
  • The male parts of a flower are the stamen (male reproductive organ), filament (stalk holding up anther), and anther (produces pollen).
  • The female parts of a flower are the pistil (female reproductive organ), stigma (top of pistil, receives pollen), style (stalk of pistil, connects stigma to ovary), ovary (holds ovules), and ovule (eggs).
• Flowers also have a sepal which is green, below the petals, and protects the flower before it opens.
• Grafting is a part of a plant attached to a different plant.
• Humans have learned to adapt plants to meet their needs through selective breeding.
  • Selective breeding is encouraging plants with certain characteristics to reproduce. (the largest fruit bearing plants breed through cross pollination)
  • Plants are selectively bred to withstand certain environmental conditions, increase yields, resist diseases, or alter the appearance or taste.
  • Genetic engineering is altering DNA to remove desired genes and combine them with another organism’s genes. This can need more fertilizer or pesticide, or introduce non-native species.

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Heat and Temperature

• Energy is the ability to do work.
  • Potential energy is stored energy.
  • Kinetic energy is energy in motion (the more moving particles, the more kinetic energy they have).
  • Temperature is the average kinetic energy of all particles in a substance. A measure of how hot or cold a substance is.
  • Thermal energy is the total kinetic energy of all particles in a substance. When two objects rub together, thermal energy is produced.
  • Heat is the transfer of thermal energy from one substance to another, due to a difference in kinetic energy.
  • Heat always transfers from hot to cold (high to low energy). This is because hotter particles move fast, and when they hit cooler particles, they cause those particles to move faster.
• The Particle Model of Matter (PMOM) is a group of statements for helping with understanding matter and how it works.
  1. All matter is made up of tiny particles.
  2. Particles are always moving. As temperature increases, particle speed increases, and vice versa.
  3. There are spaces between particles.
  4. Particles in a substance are attracted to one another. The strength of the attractive force depends on the type of particle
• There are three states of matter: solid, liquid, and gas.
  • Solid matter has particles close together as they vibrate in place, the least kinetic energy, a definite shape, a definite volume, and strong forces between particles.
  • Liquid matter has particles vibrating and moving around as they slip past each other, a definite volume, no definite shape (takes the shape of different containers), more kinetic energy than solids, and forces between particles that aren’t strong enough to hold a regular pattern.
  • Gas matter has particles with lots of space in between as they move fast, no definite shape, no definite volume, the most kinetic energy, and weak forces between particles.
• In order for matter to change states, energy must be added or removed. The stronger the attractive forces, the more energy needed to overcome the attractive forces and move apart.
  • A solid melts (fusion) into a liquid by gaining energy, and sublimates into a gas by gaining energy.
  • A liquid freezes (solidification) into a solid by losing energy, and evaporates into a gas by gaining energy.
  • A gas condenses into a liquid by losing energy, and deposits into a solid by losing energy.
• The melting point and freezing point of water is conveniently 0 degrees Celsius, and the boiling point is also conveniently 100 degrees Celsius.
• Heating or cooling results in different results:
  • Adding heat energy makes particles move faster, increases kinetic energy, increases volume, and particles move apart and collide more often. This is called expansion.
  • Removing heat energy makes particles move slower, decreases kinetic energy, decreases volume, and particles get closer and collide less. This is called contraction.
  • In thermometers, the alcohol inside expands when heated and rises to the top, and contracts when cooled and drops to the bottom.
  • In hot air balloons, hot air expands, filling the balloon with air lighter than the outside air, and therefore floats.
  • However, with water it does the opposite. As water freezes it expands and becomes less dense, while contracting and becoming more dense while melting. This is because of its molecular structure.
  • Bimetallic strips are used in thermostats (furnaces), air conditioners, and refrigerators. Two different metals are joined together, and one expands more than the other. The movement of the strips helps operate electrical switches.
• There are different ways of transporting heat energy:
  • Conduction is the transfer of heat energy through the direct contact of particles. Heat travels from particle to particle through the substance.
    • A conductor is a material that allows for easy heat transfer. (metals)
    • An insulator is a material that slows heat transfer since spaces between the particles are larger. (wood, plastic, cork)
  • Convection is heat transferred by the motion of particles in fluids. (gases and liquids)
  • When heat is added to particles, particles move faster (increased kinetic energy), particles move further apart, density decreases (fewer molecules in a space), less dense particles rise up, and dense particles move down closer to the heat. (convection)
  • Radiation is the transfer of energy through invisible waves (infrared waves). When infrared waves meet an object, it increases the kinetic energy of the particles.
    • The Sun is our greatest source of radiant energy.
    • Light, shiny objects reflect radiant energy, and dark, dull objects absorb radiant energy.
• Energy can be caused via different means:
  • Chemical energy is energy caused by chemical reactions. (burning coal, burning wood, burning fossil fuels, batteries, digestion (stored in food))
  • Electrical energy is produced when charged particles (electrons) move through a wire.
  • Mechanical energy is made by moving parts that create friction. Friction produces heat. (car breaks, sewing machine)
  • The law of conservation of energy states that energy can’t be created or destroyed, only transferred or transformed.
    • Energy that’s transformed changes from one form to another.
    • Energy that’s transferred passes along from one thing to another.
• There are also different ways for us to get electrical energy:
  • Solar energy is solar panels making energy when photons from the Sun touch photovoltaic cells, which attracts electrons and creates a circuit.
  • Energy can be made from wind by having the wind turn the giant blades of wind turbines, which generate electricity via a dynamo.
  • Geothermal energy is using the Earth’s heat and hot springs to heat water and generate electricity.
  • Hydroelectricity is generated by a dam which controls when water goes through a penstock into a turbine to generate energy.
  • Biomass is the burning of dead living things such as plants and fossils to release energy.
  • Nuclear energy is splitting an atom to unleash a lot of energy that can be used.
  • Nuclear fusion is the opposite, since two atoms are joined into a bigger one and has less radioactive byproduct.
• Homes and buildings have multiple options for heating:
  • Local heating systems heat one room or small part of a building using convection. (fireplaces, wood-burning stove, space heater)
  • A central heating system heats rooms or parts of a building from a single, central source. Heat is transferred using forced air heating or hot water heating. (furnaces, boilers)
  • Forced air heating is when air is heated by a furnace and travels through ducts.
  • Hot water heating is when water is heated by burning fuel in a boiler or furnace.
• Cooling systems remove heat from an enclosed space using a refrigerant. A refrigerant is a liquid that evaporates at a very low temperature and keeps the freezer cold. (Freon)
• Insulation reduces heat transfer, and works at keeping things hot and keeping things cold. (stone, brick, fiberglass, Styrofoam, air)
• An R-value is used for measuring the quality of an insulator. A higher value means a better insulator.
• A thermogram is an infrared photo to diagnose areas of heat loss in a building.

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Structures

• A structure has a definite shape and size and serves a specific function.
• The origin of a structure is how it was made.
  • A natural structure is found in nature.
  • A manufactured structure is made by people.
  • Natural structures can inspire manufactured structures. (duck feet and scuba flippers, spider webs and fishing nets)
• Structures can be classified by their design, which is the way they’re built. (how it’s put together, how the parts are arranged)
  • Mass structures are made by piling up materials into one design. There is little to no space inside, it’s very strong, heavy, and needs lots of materials. (beaver dams, mountains, brick walls, sculptures)
  • A frame structure is a skeleton of parts joined together that supports the weight of the entire structure. There are lots of joints, there is lots of empty space inside, it’s easy to design and build, and uses less material and therefore has a lower cost. (ladders, show shoes, spider webs, wheelchairs, fences, walls of a house)
  • A shell structure is a solid outer layer with a hollow inner area. It uses a small amount of material, is strong since force is spread through the whole structure, small weaknesses can cause failure, and they’re hard to build. (parachute, milk carton, tin can, balloon, balls, cardboard box)
  • A mix and match structure is a combination of two or more of the basic structural forms. (airplanes are shells built around a skeleton)
• The function of a structure is the purpose or job it does. Many structures have multiple functions, and it’s the first thing to consider when designing.
  • Some structures have the same function, but different designs. This is common.
• Aesthetics is the beauty of an object. This varies between different people.
• The margin of safety is the limits in which a structure is expected to perform its function safely. Structures are designed to have extra strength to withstand much larger loads than it would normally carry, so that it’s safer. (speed limits, load requirements (elevators))
• There are different types of materials to be considered when designing a structure:
  • A composite material is made from more than one material. (concrete, fiberglass, bricks, paper)
  • Layered materials have different materials pressed or glued together. (plywood, windshield)
  • Knit/woven materials are fibers twisted, looped, and knotted together. (cloth, rope, shoelaces)
• A joint is where structural parts are put together. They’re also the weakest parts of a structure.
  • Mobiles joints are joints that move and are flexible. (hinge, knee, elbow, shoulder)
  • Rigid joints are joints that don’t move and are fixed:
    • Fasteners are small parts that “pierce” through materials and bind them together. They use friction to hold the pieces together. (screws, nails, staples, dowels, rivets)
    • Interlocking shapes fit together because of their shape. (Lego, bricks, some paving stones)
    • Ties use string or rope to join things together. (thread, string, rope, shoelaces, seams in clothing)
    • Adhesives are sticky substances that hold pieces together. (glues, tape, caulking)
    • Melted joints are parts melted together using heat. Welding is melting pieces together, and soldering is melting another material around pieces.
• Mass is the amount of matter in an object, measured with a triple beam balance scale, measured in grams or kilograms, and stays the same no matter where you’re in the universe.
• Force is a push or pull that causes a structure to move or change shape. The effect of force on a structure depends on the magnitude (strength), direction, and location of the force.
  • The Newton is the standard unit for measuring force. 100 g = 1 N and 1 kg = 10 N, so on Earth, gravity pulls on each kg of mass with approximately 10 N of force. So to find the weight of an object on Earth, we multiply the mass in kg by 10 N per kg.
  • An external force is a force applied from outside a structure. (gravity, wind)
  • The load is the weight carried or supported by a structure. There are two types of loads:
• Weight is the measure of the force acting upon an object (gravity is the biggest force), is measured with a spring scale (force meter), measured in Newtons, and weight will change depending on where you’re in the universe.
• A Static load (dead load) is a non-moving, non-changing permanent force. It’s the weight of the structure itself and the non-moving load it supports. (beams, cables, rivets, steel plates)
• A dynamic load (live load) is a load that moves or changes with time (non-permanent). (vehicles and pedestrians on a bridge, gust of wind acting upon a structure)
• Internal forces act from within a structure. It’s a force that one part of a structure exerts on other parts of the same structure. They’re classified by the direction in which they act, and they can cause deformation.
  • Deformation is when a structure’s shape changes because it can’t resist internal forces.
  • Tension is the act of stretching and pulling apart. Materials fail by tearing or fracturing. (tug of war, exercise bands)
  • Compression is when a structure is squeezed. Materials fail by buckling. (springs, car crash impact, compression socks)
  • Torsion is when a structure is twisting by turning the ends in opposite directions. (twisting a towel, turning a door knob)
  • Shear is a structure’s parts pushed in opposite directions. (cutting, tearing paper, iceberg breaking)
  • Sometimes different kinds of internal forces act on a structure at the same time. Bending is compression and tension at the same time, on opposite sides.
• Builders combine materials to make a structure that can resist more than one force.
• There are different stages to the damage of a structure:
  • Structural stress is the effect of the forces acting on a structure at one time.
  • Structural fatigue is a permanent change in a structure caused by too much force being applied. (cracks, bending)
  • Structural failure is when a structure can no longer perform its function due to the forces acting on it.
  • Sometimes, structural failure is beneficial if it happens in an intentional, controlled way. (car bumper, blades of grass for sports, shear pins)
• Triangles are the strongest structural shape since they’re good at spreading force and can’t be bent easily (rigid).
  • A brace (kind of like a beam) forms a triangle at the point where pieces meet, therefore making it stronger.
  • Corrugation is forming a material into wave-like ridges or folds. They’re stronger since they form many triangles. (cardboard)
  • Trusses are frameworks of beams joined to form triangles.
• Other structural supports include:
  • A buttress is a slanted brace that supports an exterior part of a structure. (supports on the sides of a dome or arch)
  • A beam is a flat structure supported at each end. Changing its shape can increase its strength.
  • A column is a solid structure that can stand by itself. It’s used to support beams.
  • A cantilever is a beam supported by a column at one end. A double cantilever has the middle of the beam on the column, having the beam stick out of both sides.
  • Arches disperse load evenly down to the foundation. The keystone is the arch’s middle stone and prevents it from falling down.
• The base of support is the base where support begins from.
• The center of gravity (COG) is the point where downward force of gravity is acting; all the mass of the structure is evenly distributed around.
• Symmetry is balancing the arrangement of mass/parts.
• Flexibility is the ability of a material to bend under force without breaking. Tall buildings are flexible which allows the buildings to resist being deformed under strong winds (like trees in nature).
• Structural stability is a structure’s ability to maintain its position under force.
  • Stability can be achieved by having a wide base of support, a low center of gravity, and symmetry.
• Structural strength is a structure’s ability to support its own load and additional loads applied to it.

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Planet Earth

• Earth is broken up into four layers.
  • The crust is the thinnest layer and where we live on. It’s also the coldest.
  • The mantle is the thiccest thickest layer and made of very hot rock. Some parts are even liquid-like.
  • The outer core layer is made of iron, nickle, some oxygen, and some sulfur. It’s so hot it’s liquid.
  • The inner core layer is hottest and the center of the Earth. Because of the extreme pressure of being in the center of the Earth, it’s solid instead of liquid.
• An incremental change is a slow, gradual change of the Earth’s surface.
  • Weathering is the breaking down of rocks into smaller pieces (sediments).
    • Chemical weathering is when chemicals in the environment react with rocks and break them down. (acid rain, stalactites, stalagmites)
    • Mechanical weathering is physical forces wearing away at rocks. (gravity, water, rock-on-rock, frost wedging, wind, glaciers)
      • For example, moving water weathers and erodes where it’s fast, and deposits sediments where it’s slow. This creates landforms.
    • Biological weathering is living organisms breaking down rocks. (tree roots, chemicals in lichen)
  • Erosion is the movement of rocks from one place to another.
    • As an example, wind erodes away at rocks and gravity causes rock slides.
  • Deposition is sediment being dropped in a new location.
  • Another example is glaciers (moving masses of ice and snow) picking up large rock fragments and carving and scraping the land with them.
• Sudden changes are events that suddenly change the crust of the Earth.
  • A volcano is an opening in the Earth’s crust where molten rock, ash, and gas escape.
    • Inside an active volcano is a chamber where molten rock collects.
    • It starts when one plate is forced under another at a boundary.
    • Then, pressure from magma and trapped gas builds up inside the chamber, causing magma to move through channels in the rock and escape onto Earth’s surface.
    • Magma is molten rock within the Earth’s crust.
    • Lava is molten rock flowing on the Earth’s surface.
    • There are three states to a volcano:
      • An active volcano has recently erupted.
      • An extinct volcano hasn’t erupted for tens of thousands of years and isn’t expected to erupt again.
      • A dormant volcano isn’t currently erupting but could erupt at any time.
  • Earthquakes are ground vibrations caused by a sudden release of energy when plates strike each other as they’re moving. They occur along faults (breaks in the crust).
    • The focus is the first place the rocks break in an earthquake.
    • The epicenter is the place on the surface directly above the focus and where most damage occurs.
    • Seismic waves are energy waves that travel outward from the source of the broken rock. There are three types. (p-waves, s-waves, l-waves (surface))
      • The strength of an earthquake’s seismic waves is measured with the Richter Scale. It goes from 1 to 10 and an increase of 1 is an increase of 10x the amount of ground motion. (5 is 100x more powerful than 3)
      • A seismologist is a scientist that studies seismic waves.
      • A seismograph is a device that records seismic waves.
      • A seismogram is a graph made by a seismograph.
  • The Ring of Fire is an area in the Pacific Ocean where many earthquakes and volcanic eruptions occur. They happen along plate boundaries.
    • When volcanoes erupt on the ocean floor, they often create underwater mountains and ranges as the lava cools and hardens.
    • When they become very large, the mountains become islands coming out of the surface of the ocean.
  • Tsunamis are huge powerful waves caused by earthquakes in oceans.
• Rocks are made up of minerals.
  • Minerals are naturally occurring, made of elements, and have crystal structures.
    • Crystals are atoms arranged in an orderly pattern that repeats.
    • Minerals have different properties for describing them.
      • The color is the outward appearance and isn’t reliable since it can change.
      • Luster is the shininess of a mineral and is how a surface reflects light. (pearly, glassy, waxy, silky, greasy, brilliant, dull, shiny, metallic, glossy).
      • The streak is the color of the powder left behind after the mineral rubs a rough surface and isn’t always the same color as the mineral.
      • Cleavage means that the mineral splits easily into smooth, flat pieces, and a fracture is a break with rough, uneven, and jagged edges.
      • Transparent is see-through, translucent is shadowy or frosted, and opaque isn’t see-through.
      • Hardness is how easily the mineral can be scratched and is measured with Moh’s Hardness Scale.
        • The softest mineral is talc, has a score of one, and can be scratched by a fingernail, the hardest is diamond, has a score of ten, and can scratch all others but not be scratched itself.
• There are three classes of rocks that every rock can be put into.
  • An igneous rock is formed when molten rock cools and becomes solid.
  • Igneous rocks can be either intrusive or extrusive. Intrusive cool slowly below the surface making big crystals, and extrusive cools quickly on the surface making small crystals.
  • Sedimentary rock is created when sediment is compacted and cemented. They have strata (visible layers) and often have fossils.
  • A metamorphic rock is one that has been changed from one kind to another through heat and pressure over time. The initial rock is the parent, and the final is the daughter rock.
  • These can all be put into a cycle, called the rock cycle. It doesn’t have a set order and rocks are always changing.
• All the continents were originally one big supercontinent known as Pangaea.
  • Alfred Wegener originally proposed this idea in 1910.
• The Earth’s crust is divided into many slowly moving tectonic plates.
  • Continental drift is when the plates slowly drift apart from each other.
    • The plates are moving very slowly on top of a magma layer in the mantle.
    • It moves and undergoes convection currents since magma is liquid and pulls the plates in its direction.
  • Boundaries or faults are where plates meet.
    • A divergent boundary is where plates move apart. These form ridges (underwater mountains) and rift valleys.
    • A convergent boundary is where plates move toward each other. Subduction is when a plate moves under another. These form ocean trenches, volcanoes, volcanic islands, and folded mountains.
    • A transform boundary is where plates slide along each other. These result in earthquakes and faults since the movement isn’t smooth.
• A mountain is an uplifted area of land. Multiple mountains in a series or chain is a mountain range.
  • A fold mountain is a mountain formed through soil folding layers (bending). When plates collide, it causes wrinkles in the top plate; those wrinkles are mountains.
    • This is the most common mountain type.
  • An anticline is an upfold in the rock, and a syncline is a downfold in the rock.
  • Fault mountains occur along fault lines.
  • Fault block mountains are formed when faults or cracks in the crust force some blocks of rock up and some down (tension).
  • A complex mountain is formed through a combination of faulting and folding in mountains.
  • Younger mountains are sharper, and old mountains are rounder.
  • A thrust fault is a break in the Earth’s crust, across which older rocks are pushed above younger rocks.
• A fossil is the preserved remains, impression, or trace of any once-living thing from a past age.
  • Fossils are found on the surface of the earth and become exposed through weathering, erosion, earthquakes, and human activity. Paleontologists then dig in the same area to find other fossils.
    • A paleontologist is a person that studies fossils.
    • An organism dies, is buried, and pressure turns the remains into a fossil. Soft parts rarely decompose as they decompose quickly, but hard parts don’t.
  • There are different types of fossils:
    • An original remains fossil is all or part of the original organism preserved.
    • A trace fossil is evidence of animal activity fossilized. (tracks, footprints, wormholes, burrows)
    • A mold fossil is the imprint of a fossil.
    • A cast fossil is a filled in mold fossil.
    • A petrified fossil is when water enters the bone and dissolves the calcium carbonate, and a hard mineral is put in place instead.
  • Carbonaceous film is when a carbon film (imprint) is left on the surface of rocks.
• The principle of superposition is the theory that in undisturbed layers of rock, the old layers are at the bottom, and the young rock is at the top.
  • Relative dating (no not that) is determining the approximate age of rocks by looking at their position in strata.
• Earth’s history is divided into smaller units (eras) based on the appearance of different life forms. This is the geological timescale.
  • The Pre-Cambrian era was 4.6 billion to 600 million years ago. The Earth formed and the first life forms were bacteria, algae, fungi, and worms.
  • The Paleozoic era was 600 to 225 million years ago. Small amphibians, reptiles, insects, giant ferns were the new life forms. Pangaea was formed, and a mass extinction occurred at the end of the era where 96 of all organisms went extinct.
  • The Mesozoic era was 225 to 65 million years ago. The dominant organisms were dinosaurs, reptiles, flowering plants, birds, and mammals. Pangaea started breaking up, and there was a mass extinction at the end of the era.
  • The Cenozoic era was 65 million years ago to present day. The dominant organisms were birds, mammals, and flowering plants. The first human-like species came to existence, and the continents moved.

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