Download EAPS 106 Exam 3: Wildfires and Meteorites Q&A with Complete Solutions and more Exams English Language in PDF only on Docsity!
EAPS 106 - Exam 3 with 100%
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What (chemically) is fire? - correct answer ✔✔an exothermic, self- perpetuating chemical reaction initiated by a small amount of heat What is an exothermic chemical reaction? - correct answer ✔✔a reaction that releases more energy than it absorbs (ie. heat producing) What are the four components of the fire tetrahedron? - correct answer ✔✔1. fuel
- heat energy
- oxygen
- uninhibited chain reaction Name the phases of a fire in order. - correct answer ✔✔pre-ignition, combustion, smoldering What is the pre-ignition phase? - correct answer ✔✔heat causes fuels to give off vapors that can burn What is the combustion phase? - correct answer ✔✔fuels vapors combine with oxygen in a reaction that releases more heat What is the smoldering phase? - correct answer ✔✔ash cover leads to slow, low-temperature burning and prevents new fuels from igniting
What is a surface fire? - correct answer ✔✔a fire that occurs in grasses, pine needles, and shrubs near to the ground What enables surface fires and crown fires to burn easily and spread quickly?
- correct answer ✔✔their fuels have a large surface area to volume ratio (lots of exposed area to react with oxygen) What is a crown fire? - correct answer ✔✔a fire that occurs near and at the crowns of trees (canopy) where fine branches and needles burn very quickly Which type of fire moves the fastest and burns the hottest? - correct answer ✔✔crown fire What starts most wildfires in the US? - correct answer ✔✔humans start 85% of all wildfires What natural phenomenon most often causes wildfires? - correct answer ✔✔lightning Why do wildfires started by lightning tend to burn a larger area? - correct answer ✔✔they often:
- occur in remote areas
- burn longer before being noticed
- are more difficult to fight
- are often left burn as a natural process What factors influence to potential of a wildfire to spread? - correct answer ✔✔- type of vegetation
- amount of rainfall (less rainfall => more spread)
- average temperature (higher temperature => dryer fuels => more spread)
What is the mascot of the US forest service? - correct answer ✔✔Smokey the Bear What is the Legend of the Coyote (as it relates to wildfires) and what is its lesson? - correct answer ✔✔coyote brings fire down from the mountains and gives it to humans; a fire occurs and the coyote's paws are burned off; he eats his paws the next day; lesson: fire renews Why do grasses survive fires better than trees? - correct answer ✔✔only grasses can regrow from their roots Why did ancient hunters set fires in grasslands? - correct answer ✔✔to maintain the balance between the forest and the grasslands What is a fireline? - correct answer ✔✔a cleared strip of forest where all burnable fuels of been removed (preventing fires from crossing the line) What is a backburn? - correct answer ✔✔starting a controlled burn ahead of a wildfire to spend fuels before the actual fire can use them; usually used in conjunction with a fireline How does smothering stop a fire? - correct answer ✔✔it prevents oxygen from reaching the fuel thereby inhibiting the chemical reaction What is a "hotshot" crew? - correct answer ✔✔a group of 20-22 wildland firefighters that directly engage wildfires, generally the most challenging and dangerous ones; they are trained and equipped to work in remote areas with little support; they are generally organized by state and federal agencies Why are fire retardants dropped from air tankers colored red? - correct answer ✔✔to indicate where they have already been dropped (from far away -- better visibility)
What kind of plane was the first air tanker? - correct answer ✔✔crop duster (1955 -- Mendenhall, California fire) Where do air tankers usually drop their loads? - correct answer ✔✔ahead or to the sides of a fire to prevent it from spreading; dropping onto the fire is usually ineffective as the fire it too hot to be stopped directly What are the advantages of helitankers? - correct answer ✔✔they can better target drops since they don't have to be moving laterally; they can refill at smaller bodies of water; they can carry water cannons What are the disadvantages of helitankers? - correct answer ✔✔they have a lower weight capacity than regular airtankers (they can less stuff to drop); they have shorter drop ranges What is the main purpose of smoke jumpers? - correct answer ✔✔they quickly get to and fight remote wildfires before they become dangerous How do smoke jumpers go about their job? - correct answer ✔✔jump from low altitudes and attack the fire from the back using a variety of techniques (backburns, redirection, quenching, etc); they fight fires for days at a time with only a few hours of sleep during breaks What is most common cause of death for wildland firefighters? - correct answer ✔✔heart attacks How are fire shelters designed to work? - correct answer ✔✔they are a last resort measured to be used when wildland firefighters are surrounded; they reflect heat and trap breathable air
What are the most common places to find meteorites? - correct answer ✔✔Antarctica: flowing glaciers collect and deposit them, winds erode the ice and expose them Farm Land: many meteorites contain nickel which in turn contaminates farm land preventing crops from growing (making them easy for farmers to find) What are some basic facts about the Lafayette Meteorite? - correct answer ✔✔- it is Martian
- it came from a 1.3 billion year old lava flow
- it was exposed to salty water 670 million years ago
- it was ejected from the surface of mars by an asteroid impact 11 million years ago
- landed on Earth 2,900 years ago
- was discovered in a lab drawer at Purdue in 1929 How do we know the Lafayette Meteorite is Martian? - correct answer ✔✔it contains trace amounts of gas that exactly match those of the Martian atmosphere as sampled by the Viking Landers in 1980 What is regolith? - correct answer ✔✔a loose layer of dust and small particles left over from meteorite impacts; this has smoothed over the spotted surface of many asteroids Where are the majority of asteroids found? - correct answer ✔✔asteroid belt What are the Trojan asteroids? - correct answer ✔✔asteroids clustered in Jupiter's orbit What percentage of the Earth's mass does the asteroid belt add up to? - correct answer ✔✔0.05%, 4% of the Moon's mass
What is the largest asteroid and how much of the total mass of all asteroids does it make up? - correct answer ✔✔Ceres, it accounts for 1/3 of the mass of the all asteroids What are the largest four asteroids in order from least to greatest diameter? - correct answer ✔✔Hygiea (434 km), Pallas (512 km), Vesta (525 km), Ceres (939 km) Why are comets referred to as dirty ice balls? - correct answer ✔✔they consist mainly of ice and rock What is the coma of a comet? - correct answer ✔✔a cloud of gas and dust that surrounds the nucleus of the comet (the actual rock itself) What causes the tails of a comet? - correct answer ✔✔solar radiation causes (dirty) ice on the surface of the comet to sublimate and stream out of the nucleus What makes up the two tails of a comet, what directions do the tails take, and why? - correct answer ✔✔gas tail: molecules ionized by UV radiation that gets pushed directly away from the sun by the solar wind dust tail: are swept away from the comet by light pressure as it approaches the sun, falling behind the motion of the comet When do dust jets on comets turn on and off? - correct answer ✔✔sporadically, lasting for about 10 minutes What initiates dust jets? - correct answer ✔✔we don't know
How do we know the Oort Cloud is spherical? - correct answer ✔✔long-period comets come at us from all directions About how fast do asteroids hit the Earth? - correct answer ✔✔at an average of 15 km/s (32000 mph) Why are impact craters almost always round? - correct answer ✔✔the impact shock wave travels outward equally in all directions (regardless of asteroid size or impact angle) What is impact ejecta? - correct answer ✔✔material ejected from the impact of an asteroid Where does most impact ejecta land relative to the crater? - correct answer ✔✔within one diameter of the crater rim (called the ejecta blanket) What are crater rays? - correct answer ✔✔lines of ejecta that extend 10s of crater diameters What are the different kinds of craters? - correct answer ✔✔simple craters, complex craters, multi-ring basins What are the characteristics of simple craters? - correct answer ✔✔caused by small asteroids, bowl-shaped, a few km across What are the characteristics of complex craters? - correct answer ✔✔caused by medium-sized asteroids, have a central peak and terraced walls, 10s of km across
What are the characteristics of multi-ring basins? - correct answer ✔✔caused by large asteroids, have multiple rings at different heights, 100s of km across Why are some of the largest Lunar impact craters black and smooth? - correct answer ✔✔newer lava flows have smoothed out the surface, not covered in as much dust from impacts Does the Earth or the Moon get hit with more asteroids? - correct answer ✔✔Earth Why are there more impact craters on the Moon than on Earth? - correct answer ✔✔erosion and other natural processes erase the evidence of craters Why does the Kentland Crater (in Indiana) not look like a crater? - correct answer ✔✔glaciers have removed the surface topography (12000 years ago) What is a shatter cone? - correct answer ✔✔cone-shaped rocks that form from shock wave propagating through physical material; new cones are generated whenever a cone hits an inconsistency in the material it is traveling through What is shocked quartz? - correct answer ✔✔formed when shock waves pass through quartz causing small fractures in two distinct directions What is the evidence that a large impact killed the dinosaurs? - correct answer ✔✔a thin layer separated Cretaceous from Paleogene (modern era) sediments all over the world containing large amounts of iridium, shocked quartz, and soot How did the asteroid impact kill the dinosaurs and 75% of other species? - correct answer ✔✔- heating of ejecta on reentry caused global wildfires
- detonating nuclear weapons along its surface to knock it off course
- throwing a heavy spacecraft at the asteroid Why is Mars the most explored planet? - correct answer ✔✔it holds the greatest chance of finding evidence of past or present extraterrestrial life What is the closest planet to Earth on average? - correct answer ✔✔Mercury; planets that may have close orbital paths to Earth will be very far away from Earth when Earth and the planet are on opposite sides of their orbit; Mercury is most consistently close to Earth Did Mars have liquid water on its surface in the past? - correct answer ✔✔yes, it had lakes and rivers Does Mars have liquid water on its surface today? - correct answer ✔✔no How do we know there used to be a lot of water on the surface of Mars? - correct answer ✔✔evidence of water flows on the surface (sediment deposits and erosion): dry river channels, dry lake beds, and possible ocean basins are still visible What happened to the water on the surface of Mars? - correct answer ✔✔it has been frozen as ice buried underneath the Martian surface What is the best way to search for ancient life on Mars? - correct answer ✔✔apply what we know of life on Earth to life on Mars; more Martian exploration Why was the Jezero crater that site for the Martian rover Perseverance? - correct answer ✔✔it was once filled with water making it a good candidate for a region able to support ancient/present extraterrestrial life
What was the fate of the Apollo 1 astronauts? - correct answer ✔✔a fire broke out during a test in the pod which spread rapidly due to a pure-oxygen environment and killed all the astronauts; this tragedy led to better safety precautions on future missions What was the experience of the Apollo 13 astronauts? - correct answer ✔✔an explosion caused by faulty wiring on their way back from the Moon forced them return to Earth in the command module using a gravity assist from the Moon; all 3 survived Why did the Challenger space shuttle explode? - correct answer ✔✔an aft joint failed upon ignition (due to an O-ring failure), burned through the strut attaching it the booster to the external tank in 70 seconds, crushing the external tank, releasing the oxygen and hydrogen which ignited to blow the ship to pieces What safety violations occurred during the launch of the Challenger that led to its ultimate unsavory demise? - correct answer ✔✔1. implications of O-ring damage were ignored
- launch took place in colder temperatures than were tested in
- NASA management ignored the safety concerns and objections of engineers (the engineers rightly believed it was not safe to launch) What happened to the space shuttle Columbia? - correct answer ✔✔in 2003, it disintegrated during reentry killing seven astronauts on board Why did the space shuttle Columbia explode? - correct answer ✔✔foam from the external tank broke off, damaging the tiling on the orbiter; the form debris had hit the shuttle over 15,000 times, causing over 100 dents over the 5 years before Columbia; the problem of foam-breaking off had been known for years
How can gravity by simulated in space? - correct answer ✔✔by spinning: the rotation generates a (fictitious) centrifugal force that, at sufficient angular velocities, can accurately match the pull of gravity What would kill you first if you took your helmet off in space? - correct answer ✔✔suffocation How do astronauts move about the surface of the Moon? - correct answer ✔✔by hopping and skipping; because the Moon's gravity is far less than that of Earth, astronauts from hopping/skipping easier than walking
