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Biology Objective 3 Demonstrate an understanding of the interdependence of organisms and the environment. Biomes Identified by biotic and abiotic factors • Biotic – what kinds of plants and animals live in it. • Abiotic – Nonliving characteristics such as soil type, rainfall amounts, and average temperature cycles. Temperate Desert Forest Name Tundra Grasslands the Biome Tropical Tiaga Rainforest What are they referring to? • Biosphere – The entire area of the planet that supports life. • Biome – An area defined by specific abiotic and biotic factors. • Community – The groups of living things in an area and how they relate. Ecology – The study of the relationships among living things • Symbiosis is a close relationship between two living things. • When both are helped it is called mutualism • When one is helped and there is no effect on the other it is called commensulism • When one is helped and the other is harmed it is called parasitism Mutualism . . . Sharks are cleaned by a little fish known as a Remora. The shark never eats them since they clean bacteria off of the shark. Since both species are helped, this is mutualism. Commensulism . . . Orchids live high in tree-tops on the branches of large trees. They do not harm the tree, but they are helped by being raised up into the sunshine and receiving water. Parasites . . . Parasites harm or kill the host. A good example is a tape worm. It intercepts all of the hosts food, causing the host to starve to death. 35 Clown fish are small reef fish that seek protection from predators by sheltering themselves among the stinging tentacles of sea anemones. Clown fish are very territorial and can potentially scare off predators of sea anemones. This relationship is an example of -A neutralism This is not a type of symbiosis Incorrect Since both are helped, it B mutualism is of mutual benefit or C parasitism Neither is harmed so this is incorrect D commensalism Means only one is being helped and the relationship has no effect on the other – also incorrect What is helped? Both the ants and the tree. This is the definition of: All energy on the earth comes from the sun. Energy Diagrams At one end of the diagram are plants. They are called producers since they are capable of turning sunlight into food by photosynthesis. They pass 10% of the energy they absorb to animals that eat them. Consumers 1st Order Consumers eat only plants and are also called herbivores. 2nd Order Consumers eat only animals and are called carnivores. 3rd Order Consumers animals that eat other animals, they are also known as carnivores 39 Wolves and hawks are at the same Trophic trophic level level because they — Means 1st , A both live on land 2nd or 3rd B are both large mammals Order C both eat primary consumers Consumer D have similar hunting patterns 10% Energy Rule – Only 10% of the energy moves up to the next trophic level. Decomposers If we apply the 10% rule, 10% of 43 Approximately how much the 1000 kcal of the plant is of the energy available in the consumed or 100 kcal, and 10% tissues of the producer is of that is 10 kcal which is 1% of eventually incorporated into the original 1000kcal, but only 3 the tissues of a secondary kcal is available to the tissues so consumer? it is A. A Less than 1% B Between 20% and 30% C Approximately 50% D More than 50% Food Chain – One of many feeding relationships in a community • Arrows in a food chain show the direction of energy flow. • This is not the only feeding relationship for these organisms. • When several or all of the food relationships are shown it’s a . . . Food Web Food Webs • Food webs attempt to show all the feeding relationships in a community. • The direction of the arrows shows the direction of energy flow. • At the bottom of every web and every chain is a plant. These are the only things that can turn sunshine into food. Since the Gulls are at the top of the food web, they would have the highest accumulation of everything but energy. 37 Which of these groups of organisms would most likely have accumulated the largest concentration of a long-lasting chemical pollutant in their bodies? A Phytoplankton B Zooplankton C Lake trout D Gulls • Prey are the animals that are eaten as a food source for the . . . • Predator This is the hunter animal. The population of the predator must be less than the prey or they do not have enough food. Population (100s) Predator and Prey Time (months) Prey Predator To increase the predator population you could do what? 24 Which of the following is most likely to cause increases in a predator population? F Fewer prey Reduces available food – Nope! G A reduction in competition Less predators, they H More parasites would Less and prey, bepredators sick or dying! J A period of drought they’d be gone looking for water! Population (100s) Carrying Capacity Time (months) P rey P redat or • This is the maximum number of a specific population that an area can support with enough food and living requirements. It is shown by a line on population graphs for a specific species. Water Cycle • Precipitation (rain and snow) fall on plants and ground. • Plants respire and evaporate water back into clouds. • The ground filters the water run-off into the lakes where it evaporates again. 21 The diagram shows physical changes that occur in the water cycle. Which of these shows condensation? A Q Precipitation B R Run Off of ground water C S Evaporation DT Carbon Cycle • Glucose C6H12O6 is produced by plants, eaten by animals. Photosynthesis • Animals and plants exhale CO2 which is taken in by plants to make glucose Cellular Respiration Nitrogen Cycle Nitrogen Cycle • Lightening and bacteria in the ground “fix” Nitrogen into a form usable by plants. • It is absorbed by plants, through their roots as nitrates, so they can be used to build amino acids essential for building proteins, enzymes and the nitrogen bases of DNA. Rock Cycle Man’s Effects on the Environment • Ozone O3 is a protective layer at the top of the atmosphere. • However, when it occurs near the ground, it is very harmful to all living things, it is SMOG Man’s Effects on the Environment • More than 90% of fresh water is locked in ice at the polar caps and in glaciers. • Much of the fresh water is polluted by land run-off, dumping of wastes and excess heat directly into lakes, oceans and rivers. Man’s Effects on the Environment Global warming, also called the Greenhouse Effect is caused by excess burning of fossil fuels and destruction of our oxygen producing protista in the oceans, and deforestation on land. Less plants means less oxygen and more CO2. Evolution: The process of change over time. • There are natural variations in all populations. • As climate changes occur, and as pressures in terms of food, space, shelter and predation occur, some variations allow a species to survive. • The members who survive, reproduce causing the change to become a characteristic of the species. Speciation: Separation into new species. • Geographic isolation can cause two different natural variations to become prominent causing 2 separate species. • Reproductive isolation can have the same effect. What is extinction and what causes it? • A population is extinct when the last of that species is dead. • Example: There are no more dinosaurs. • What happened? Their habitat was destroyed. When they no longer have what they need to live, they die. Fossils • These are imprints or remains of living things. • In undisturbed layers of sedimentary rock, the deeper it is, the older it is. • Give us information about extinct species. Homologous vs. Analogous Structures • Homologous means they • Analogous means they have the same origin, but have the same function but may be different now. come from different origins. • Example, the upper arm bones in dogs, cows, cats • Example, bird wings and and monkeys. wings of bats. Viruses • Viruses are not alive because they can not reproduce on their own, and • They do not grow and develop and • They do not exchange with their environment Viral Illnesses • Measles, mumps, colds, influenza, Cold Sores, mononucleosis, Epstein-Barr virus are all illnesses that are caused by a virus. • A Virus is has a coat, a strand inside of DNA or RNA, and some type of attachment appendage. Bacteria • Bacteria can cause illnesses too, however 90% of all bacteria is helpful, NOT harmful. • Without bacteria, you would not be able to make or eat cheese or ice cream. Without them, you would be ill most of the time. • Strep Throat and Staph infections are examples of bacterial infections. Class TAKS Review Objective 4 Matter and Change Matter • Anything that has mass and takes up space. • Energy is NOT matter Matter is divided into 3 types: • Elements • Compounds • Mixtures The 3 types can be further separated in two categories: • Pure Substances • Elements are the simplest pure substances • Mixtues are not pure substances Compounds which and wewhen will two deal are formed or more withelements them inshare a few electrons or become minutes. ions that attract other elements. Atoms are. . . • The smallest part of a single element. • The basis of all matter. • Made of mostly empty space. • Have a positive core or nucleus. • Have electrons in orbit in clouds. 4 Basic Types of Elements • Metals: found on the left and center of the Table of Elements • Non-metals: found on the right side of the Table of Elements • Metalloids: found along the stair-step line • Synthetic: made in the laboratory and not yet found in nature – many of the Actinide and Lanthanide series and very large # elements. Where are the metal elements? Left of the Stair-step line! Properties of Elements Metals • Metals are: – Conductors – Lustrous – Electron donors – Malleable – Ductile Where are the nonmetals? To the Right of the stair step line, and Hydrogen! Properties of Nonmetals • Nonmetals are brittle, insulators, electron acceptors • Usually form negative ions (except H) • Many are gases at room temperature • Found to the right of the stair-step line 23 According to the periodic table, which element most readily accepts electrons? • A Fluorine •Fluorine B Nitrogen only needs 1 electron • This is a nonmetal, so it accepts to electrons completebut its itshell of 8,share so it will also 1-. them as initNO will accept from any other 3 •element C Arsenic very very very easily. • This is a metalloid, so it only This periodicaccepts property sometimes electrons. increases as you move up and • D Aluminum left in the except for the • This is a table, metal so it donates electrons. Noble Gases. The BOHR Model of an Atom • This is the first model to have a nucleus with protons and neutrons. • The electrons are in various energy levels and circle the nucleus. • Model most people draw today. Use the Table provided! What do the numbers mean? 11 Na 22.990 sodium This is the atomic number. It is the number of protons in a single atom of this element. By the way, its also # of electrons. The symbol for this element. This is the atomic mass, it is the number of protons + neutrons, or the mass of the nucleus of an atom. This is the name of the element. Diatomic Elements – Nonmetals that come as molecules • 7 Elements are di- (2) atomic (atoms) • The easy way to remember them is by the name •Br I N Cl H O F 3 Which of the following groups contains members with similar chemical reactivity? A Li, Be, C B Be, Mg, Sr C Sc, Y, Zr D C, N, O Lets look at the Table provided. • To have similar chemical properties of any kind, they must be in the same Group or Family. • Groups are columns, so the answer would be •B Chemical Reactivity • Metals increase in reactivity left and down. • Nonmetals become more reactive up and to the right. • Most reactiveF metal is? r • Most reactive nonmetal is?F Changes in Matter – Physical or Chemical? • Physical changes are changes in the state of matter. They do not change the substance. (Melting, boiling, condensing, freezing, cutting) • Chemical changes are reactions that result in new products with new properties. Changes in Matter – Physical, Chemical or Nuclear? • Physical changes do not • Chemical changes are change the substance. also called chemical The state of the matter reactions. may change, but it keeps • When a different its own properties. substance is produced • Cutting a piece of wood than what was present does not change the at the start, a chemical wood, it is simply change has occurred. smaller. Nuclear Changes: Fission and Fusion • Fusion occurs when the nucleus of one atom is joined by the nucleus of another. • This is the reaction that occurs on the sun and stars. • It produces extreme energy release. • Fission occurs when the nucleus of an atom ejects particles and energy when hit by a subatomic particle such as a neutron. • This also causes a release of extreme energy and is the basis of atomic energy plants and bombs. Density = Mass / Volume THIS IS FROM THE FORMULA PAGE 25 A block of maple wood with a volume of 405block cubic centimeters density If the is cut in half, youand cut athe mass inofhalf AND 3 is sawed in half. The density g/cm you0.67 cut the volume in half, so Mass/2 or Volume/2 of the two smaller blocks is now — A one-fourth original density Mass x 2the(which is really 1) so . . . . Volume the2 original density B one-half C two times the original density D the same as the original density 20 A sample of an element has a volume of 78.0 mL and a density of 1.85 g/mL. What is the mass in grams of the sample? Record and bubble in your answer to the nearest tenth on the answer document. Use the formula page, D = M/V x 1.85 g/mL = 78.0 mL Multiply both sides by 78.0 mL and you get: 144.3 g Grid it in! Law of Conservation of Matter • Matter can not be created or destroyed. • The total mass of the substances before they are mixed is equal to the total mass as a mixture. Chemical Reactions Since matter can not be Reactants Products created or destroyed, chemical reactions 100g total = 100g total must be balanced in terms of mass. The amount of mass you start with must be equal to the mass of the products. 39 According to the law of conservation of mass, how much zinc was present in the zinc carbonate? Since matter can not be created or destroyed in chemical A 40 g B 88 g C 104 g D 256 g reactions, the mass on both sides of the arrow must be equal. So 64g + 192g = 256g and 152 g + Zinc = 256g There must be 104g of Zinc. Answer C. Chemical Equations • Whole numbers written in front of formulas are called coefficients. For example, 4 C6H12O6 indicates that there are 4 molecules of glucose sugar. • To determine how many total atoms of each element are present, multiply the coefficients by the subscripts for each element. • 4 C6H12O6 would contain 24 atoms of carbon (4 x 6), 48 atoms of hydrogen (4 x 12), and 24 atoms of oxygen (4 x 6). To balance equations: • The number of atoms of each type of element on the reactant side (left of the arrow) must be equal those on the product side (right side of the arrow). 2 H2 + O2 2 H2O • There are 4 hydrogen atoms on the left (2 H2) and 4 hydrogen atoms on the right (2 H2O) • There are 2 atoms of oxygen (O2) on the left and 2 atoms of oxygen on the right (2 H2O). When a subscript is missing, it is understood to be 1. 2 K +2 H H OH 2O 2 KOH + H2 19 What is the coefficient for H2O when the above equation is balanced? • A 1 To balance this equation, make water HOH, then you will see that you need 2 H • B2 and get 2 OH groups. • C3 That means the KOH gets a coefficient of • D 4 2, the K gets a coefficient of 2 and The water must also get a coefficient of 2. Balance the equation below, the boxes should get the coefficients. 2 2 Which element does not have the same number of atoms on both sides? Oxygen. It has 2 on the reactant side and 3 on the product side. If we put a coefficient of 2 in front of PbO, we will now have 4 O and 2 Pb on the right. By placing a coefficient of 2 in front of the reactant, we have 2 Pb and 2 x 2 O. That means it is balanced! Answer? C The 3 types can be further separated in two categories: • Mixtures are • Pure Substances notCompounds pure substances. which are formed when its two Each part of a mixture keeps more elements own properties,orand can be share electrons or become separated out byions a physical that attractchange. other • Elements are the simplest pure substances elements. Decide if the substance is Element, Compound , or Mixture? 1. Water 1. Compound 2. Table Salt 2. Compound 3. Oxygen 3. Element 4. Dirt 4. Mixture 5. Air 5. Mixture/Solution Click Mouse button to see answers! Let’s try a few more! 6. Copper 6. Element 7. Soda 7. Solution/Mixture 8. Steel 8. Solution/Mixture 9. Rain 9. Mixture 10. Ice-cream 10. Mixture Click Mouse button to see answers! Properties of Mixtures: •Each substance retains its own properties. •Substances can be sent in any amount. •Substances can be arated by simple a l m e a n s. pre sep physic There are two types of mixtures: • Heterogeneous• Homogeneous- same mixture is not the composition throughout. same from place to place. – Kool-aid, air, brass. – Chocolate chip cookie, gravel, soil. Separating Mixtures – Physical Changes • Separation of mixtures could be: • Magnetic removal (if there is Fe, Ni, Co) • Filtration (if there are large particles) • Hand sorting particles • Decanting (pouring off the less dense liquid) Another technique for separating mixtures: Evaporation: changing from a liquid to vapor state– leaves behind the other component. Distillation: – Process used to remove vapor from liquid by heating – Great for separating two or more liquids which have different boiling points. So, what is a suspension or colloid? •o Suspensions Colloids havehave small larger particles, particlesoften that are visible not in size. visible by just looking. An example would be coffee. o The particles can be •filtered However, out. they show the Tyndall Effect (see the o It scatters laser light light line).– No Tyndall Effect. • They can not be separated filtering. o by If left undisturbed, the particles will settle to the bottom. Solutions: 2 parts –S o l v e n t - t h e m o s t abundant substance in the solution. –S o l u t e - t h e l e a s t abundant substance in the solution. – Homogeneous: You can not see any particles of either part! The three methods to increase the rate of solution for a solid are? •Heat it! •Crush it! •Stir it! the amount of each solute that will dissolve in 100g H20 at each temperature. Saturated is on the line. Unsaturated is below the line. Supersaturated is above the line. Grams solute/100 g H2O How much solute will dissolve? A solubility curve shows Try this one! 49 According to the graph, about how much hemoglobin would be saturated at an O2 pressure of 7.3 kPa? A 32% B 67% C 89% D 92% Concentrated or Dilute? • A concentrated solution has as little solvent as possible. • A dilute solution has added solvent. • After adding more solvent, there is still the same mass of solute that you started with. pH is a measure of the Strength of Acids & Bases • Acids have 0-6.99 pH • Bases have 7.01-14 pH • Remember because A begins the alphabet and zero begins numbers • Litmus turns red in acids and blue in bases • Phenothalein turns pink in a base and stays clear in acids. Higher pH levels means? 33 Two clear solutions are placed in separate beakers. The first solution has a pH of 4, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting pH is 5, the second solution must have — A fewer suspended solids and have no Solutions are homogeneous Nothing is mentioned about temperature so B is invalid. suspended solids. B a lower temperature NaCl solutions are neutral so have no effect on pH. C more dissolved salt (NaCl) particles D a higher concentration of OH– ions TAKS Objective 5 Motion , Forces and Energy Energy Is defined as the Ability to do Work Energy has Two Types: Kinetic (Energy of Motion) and Potential (Stored Energy) Kinetic Energy KE = ½ m v 2 Ex: A moving car has the ability to do work on the light pole if it hits it. Potential Energy 2 possibilities Gravitational PE Object lifted to some height Elastic PE - A stretched or compressed object (spring or rubber band) Gravitational Potential Energy or Will it fall? GPE = m g h m is the mass of the object in Kg, g is the acceleration due to gravity which is 9.8 m/s2 on earth and h is the height in meters Use the formula page! PE = mgh 41 What is the potential energy of the rock? A 59,900 joules m = 95 kg g = 9.8 m/s2 B 64,600 joules h = 100 m C 93,100 joules 2 x 100 = 95 D kg121,600 x 9.8 m/s joules 93,100 joules C Law of Conservation of Energy • Energy can change forms, but is never created nor destroyed • Loss in one form = gain in an another form • A falling object speeds up as it falls to the ground; PE decreases as KE increases. The KE it has at impact = the PE it had before it fell. Example: A falling object speeds up as it falls to the ground; PE decreases as KE increases, the KE it has at impact with the ground is equal to the PE it had before it fell Energy can be conserved in Non-Mechanical forms The chemical energy in a battery transforms into electrical energy Any reaction where more energy is given off than is used to start it is Exogonic An Endogonic reaction absorbs energy and causes cooling Electrical Energy Moving electrons in a path is electricity • Electrical Potential Difference (v) is measured in Volts • The rate of moving electric charges, Electric Current (I), is measured in Amperes • Resistance or opposition to the movement of the energy is called Resistance (R). Circuits – 2 types • Series circuits are the most simple. • One (1) path for the current to travel. • Contains an energy source, a path, and a load (something for it to do, like a lamp) Circuits – 2 types • Parallel circuits provide more than one path for the current to travel. • Most circuits are parallel, since if one lamp goes out, the others can stay lit. 6. Which switches, if opened, will cause the light bulb to stop glowing? F. Q G. R It is the only H. S switch in J. T series to both the battery and light. Thermal Energy A body contains internal KE due to the motion of its atoms ( they are constantly wiggling and jiggling) Thermal Energy is the total internal KE of a body Temperature is the average KE of a body Heat- Transfer of Thermal Energy Three forms of heating: 1. Conduction-direct contact, a pot heating on a stove (solids) 2. Convection- heating by circulating fluids, (gas and liquid) heating from a fireplace And. . . 3. Radiation – Transfer of Electromagnetic (E.M.) Energy • Objects are heated when exposed to infrared radiation • The suns heats the earth by sending infrared radiation along with other forms of E.M. energy 3.0 x 108 meters through empty space Heat moves by conduction in solids since the particles are close together and vibrate. . . 43 Heat convection occurs in gases and liquids. Heat convection does not occur in solids because solids are unable to — A absorb heat by vibrating B transfer heat by fluid motion C emit radiation by reflecting light D exchange heat by direct contact Solids do radiate heat to their surroundings 2 The primary way liquids and gases transmit heat is by the process of — F reflection G conduction H radiation J convection Fluid heat movement is convection. Fluid motion occurs in liquids and gases. 50 A solar heater uses energy from the sun to heat water. The heater’s panel is painted black to — Convection is movement of heat in fluid matter, heat loss improve would be from a solidemission exterior – infrared Not Gitsradiation Painting aF substance will notofchange conductivity – reduce the heat lossItbywould convection currents That is a G property of metals. have to be made of a improve to absorption of infrared different H substance change that: Not Jradiation J reduce the heater’s conducting properties Emission is giving off – we want to absorb: Not F Nuclear Reactions Fusion occurs when two atoms combine to form a new element. The sun produces all of its energy through fusion. Two hydrogen atoms combine to form a Helium atom from the great gravitational forces and pressure in the sun’s core Nuclear Reactions Fission • Fission is the splitting of nucleii of large atoms such as Uranium and Plutonium • Produces large amounts of infrared radiation and other forms of E.M. Energy such as Gamma Rays • Currently, it is the main form of Atomic Energy on Earth Radiant Energy or Electromagnetic Energy (EM) • All radiant energy travels at 3.0 x 108 m/sec in space • Velocity of a wave = wavelength x frequency • Visible light is just one type of EM Energy All of the forms of radiation given off Electromagnetic Spectrum by vibrating electric charges Radiation comes in the form of vibrating or “throbbing bundles of energy” called photons The frequency of the vibrating electric charges determines which type and how much energy will be given off • The entire E.M. Spectrum in order from lowest to highest frequency Radio waves: AM and • • • • • • FM Microwaves: cooking Infrared: heat Visible: (ROYGBV) Ultraviolet: tanning Xrays: medical Gamma: Waves - Energy carried by rhythmic disturbances • Two types: • 1. E.M. radiation move through empty space • 2. Mechanical require a medium (air, water or any type of matter) for movement Waves - 2 Types All waves have similar properties • Frequency- the number of vibrations per second or the speed of the movement of the vibrating particles • Amplitude – the size of the movement of the vibrating particles • Both are controlled by the disturbance that created the waves Velocity of all waves v=f λ f-frequency and λ is wavelength (distance between identical points on two consecutive waves) Reflection- bounce off barriers in regular ways Refraction- waves can change direction when speed changes Transverse Waves • In Transverse Waves particles vibrate at right angles to the direction the wave travels. • Ex. E. M. Waves, waves on a slinky or rope coil, ocean waves Longitudinal or Compress ional Waves Vibrating particles move back and forth along the direction of the wave velocity Parts consist of compressions and rarefactions Ex. Sound Waves Sound Waves are Compression Waves Sound is produced when a compression is made. It requires a producer and a medium to travel through. The more elastic the object, the faster sound travels. Sound acts like other waves • Echoes are reflected sound waves • Sonar uses echoes to judge distance to obstructions • Human hearing is 2020,000 Hz, below 10 Hz is infrasonic, and above 20,000 Hz is ultrasonic. Forces and Motion • Forces can create changes in motion (acceleration) • Deceleration is negative acceleration Motion can be described as • a change in an object’s position • Average velocity (speed) is the change of position of an object over time Velocity Graphs V = distance time • Velocity (v) is the slope (rise over run) of a position (d) vs. time (t) graph Distance (m) Velocity 60 40 Series1 20 Series2 0 1 3 5 7 9 11 13 15 Time (sec) Acceleration Graphs Acceleration Velocity ((m/s)(m) • Acceleration (a) is the slope of a velocity (v) vs. time (t) graph • Plotted on a distance vs. time graph, acceleration is an exponential curve 60 40 20 0 1 3 5 7 9 Time (sec) 11 13 15 Acceleration is a change in an objects velocity (speed or direction) • When an object’s speed changes over time it is accelerating (or decelerating) • A = vfinal – vinitial time • Units for acceleration m/s/s or m/s2 Definition of a Force • A Force is a push or a pull Balanced Force • A force that produces no change in an object’s motion because it is balanced by an equal, opposite force. Unbalanced Forces Are forces that results in an object’s motion being changed. + Friction A force that acts in a direction opposite to the motion of two surfaces in contact with each other. Friction Friction causes an object to slow down and stop. Since the amount of energy stays constant, the energy becomes heat. Newton’s 1st Law of Motion • Object in motion stays in motion Newton’s 1st Law of Motion • And Objects at rest stay at rest Newton’s 1st Law of Motion • Until they are acted upon by unbalanced forces. Inertia or Newtons 1st Law • Tendency for an object to stay at rest or moving in a straight line at a constant speed. • The mass (m measured in kg) of an object determines its inertia Newton’s 2nd Law of Motion Force = Mass X Acceleration F=ma Weight (pull of gravity) is a commonly measured force, calculated by F=mg, g is the acceleration due to gravity 9.8 m/s2 Newton’s 2nd Law of Motion The greater the mass of an object, the greater the force required to change its motion. Newton’s 2nd Law of Motion • The greater the acceleration of an object, the greater the force required to change its motion. Newton’s 3rd Law of Motion • For every action force there is an equal and opposite reaction force. Newton’s rd 3 Law of Motion All forces come in actionreaction pairs Ex: feet push backward on floor, the floor pushes forward on feet Work • Work: using a force for a distance • W=Fxd • The work done by forces on an object = changes in energy for that object. • Work and Energy are measured in Joules • 1 Joule=1 Newton • meter Why use a machine? • In an ideal (perfect) machine the work put into the machine (Win) = the work put out by that machine (Wout) Machines make work easier • The ideal mechanical advantage of a machine (IMA) of a machine is the number of times the output force is larger than the input force IMA=Fout/Fin • A machine can only make this happen by moving the input force through a farther distance than the output force • Fin • din=Fout • dout Real Machines use Energy • No real machine is 100 % efficient. i.e. none put out more work than is put in • Efficiency of a machine is work output/work input X 100 % • Eff = Wout X 100% W in Machines use power • Power: the rate at which energy is used (work is done) • P=Work/time • Power is measured in H.P. or watts • 1 watt = 1 Joule 1 sec 6 Types of simple machines • Some Simple Machines: • Inclined planes • Screws • Pulleys • Wheel and axle • Levers • Wedge Universal Law of Gravitation All objects in the universe attract each other by the force of gravity Universal Law of Gravitation 1) the mass of the object doing the pulling, and Gravity varies depending on two factors: 2) the distance from the center of that object On Earth gravity = 9.8 m/s/s • For every second that an object falls its speed increases by 9.8 m/s