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50 Cards in this Set
- Front
- Back
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Water is able to conduct heat far more efficiently than air because it is:
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More dense than air
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Divers are most affected by what form of heat transmission:
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Conduction
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Arrange the list of colors by the order that they disappear as you descend:
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Red, orange, yellow, green, blue, and violet
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Refraction is caused by the process of:
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light traveling at different speeds as it passes through different substances
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When viewed under water, objects appear, _____ by a ratio of about _____.
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closer/4:3
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Visual reversal refers to an object’s tendency to appear:
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further away than its actual distance
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Light waves contain ____, while sound waves are comprised of ___.
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Electromagnetic energy/mechanical energy
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Because sound results from vibration, the ____ the medium, the better the sound is transmitted. This is why sound travels ____times faster in water than in air.
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the greater the elasticity/four
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According to Archimedes’ Principle, any object wholly or partially immersed in a fluid is buoyed up by a force____.
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equal to the weight of the fluid displaced by the object
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Approximately how much water must be displaced to bring a 500 kilogram/900 pound object to the surface if the object displaces 300 liters/10 cubic feet of sea water?
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10cuftx64lbs/cuft=640lbs; 900lbs-640lbs=260lbs: 260lbs/64lbscuft=4.06cuft
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An object weighing 350 kilograms/750 lbs and displaced 300 liters/10 cubic feet is lying in 15 meters/50 feet of fresh water. If a drum is to be used to lift the object to the surface, how much water must be displaced from the drum?
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10cuftx62.4lbs/cuft=624lbs; 750lbs-624lbs=126 lbs; 126lbs/62.4lbscuft=2.02 cuft
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The absolute pressure at a depth of 90meters/300 feet of seawater is:
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300ft/33ftatm=9.09atm, 9.09atm+1atm=10.09ata~10ata
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The ambient pressure at 30 meters/100 feet of seawater is:
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100ft/33ftatm=3.03atm; 3.03atm+1atm=4.04ata~4ata
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The gauge pressure at 23 meters/76 feet of depth in freshwater is:
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76ft/34ftatm=2.23 atm gauge
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A balloon containing 30liters/1 cubic foot of air is released from 10ata. If it does not explode, calculate the volume for air in the balloon upon reaching the surface.
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10atax1cuft=1ataxV2; 10ata/cuft=1ataxV2; 10cuft=v2
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A balloon is filled with 60liters/2cubic feet of air at 30 meters/100 feet of seawater. What will be the approximate volume of the balloon if it is taken to a depth of 90 meters/300 feet?
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2cuftx4ata=P2x10ata; 8cuftata=P2x10ata; .8cuft=P2
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The air that a diver breathes from a scuba cylinder at 50meters/165 feet of seawater is ____ as dense as the air breathed from the same cylinder at the surface.
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165ft/33 ft=5; 5+1atm=6ata=6 times
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If it takes a diver one hour to breathe all the air from a scuba tank at the surface, approximately how long will the air in that tank last at 30meters/99feet?
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60mins/4ata=15 minutes
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If it takes a diver 40 minutes to breathe all the air from a scuba tank at the 20meters/66 feet, approximately how long will the air in that tank last at 30 meters/99 feet?
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40mintues*3atm=120minutes; 120 minutes/4atm=30 minutes
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A scuba cylinder is filled to capacity at room temperature. Describe what would happen to that cylinder if it was taken on an ice dive (water at or near freezing).
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The volume would remain unchanged, but the pressure would decrease.
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A scuba cylinder containing one percent carbon dioxide at the surface is taken down to a depth of 30meters/99 feet. What is the percentage of carbon dioxide in the cylinder at this depth?
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1% because percentage does not change
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A gas mixture is comprised of 21% oxygen, 78% nitrogen, and 1% carbon dioxide. At a depth of 20 meters/66 feet of seawater, what is the partial pressure of the nitrogen?
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3atax78%=2.34ata
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A scuba cylinder containing 1.5% carbon monoxide at the surface is taken to a depth of 30meters/99 feet. If a diver were to breathe from the cylinder at this depth, it would have the same physiological effect as breathing ___percent carbon monoxide at the surface.
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4atax1.5%=.06 or 6% equivalence
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If a glass of water is placed within a pressure pot and pressurized to 2ata for several days, what will have if the pressure is then increased?
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The pressure of the gas within the liquid will: increase because the pressure is increased
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Because our tissues cannot hold any more gas pressure at sea level, our body is referred to as being:
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saturated
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Water is able to conduct heat about ____ times faster than air.
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20
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_____, a form of heat transmission, has the greatest affect on heat loss in a diver while ____ is the form that has the least affect.
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Conduction/radiation
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A process called ___ refers to the tendency of light to ___ as it passes through two mediums with different densities.
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Refraction/bend
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At times, object viewed underwater appear more distant than they actually are. The phenomenon is called “____” and the factor that primarily influences its occurrence is _____.
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Visual Reversal/turbidity
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The density and elasticity of a medium has what effect upon the transmission of sound?
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The denser and more elastic the medium, the better sound is transmitted.
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Sound travels approximately ___ times faster in water than it does in air.
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Four
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Divers have difficulty determining the direction of sound underwater because:
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there is an insufficient delay between the sound striking one ear before the other.
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Approximately how much air must be added to a lifting device to bring a 600 kilogram/1200 pound object to the surface? The object lies in 30 meters/100 feet of freshwater.
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The answer cannot be determined from the data provided
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A 200 kilogram/440 pound anchor that displaces 127 liter/4.5 cubic feet of water lies on the bottom in 17meters/56 feet of sea water. What is the minimum amount of water that must be displaced from a lifting device to bring the anchor to the surface?
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4.5cuftx64lbscuft=288lbs;440lbs-288lbs=152lbs;152lbs/64lbscuft=2.37cuft
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A 175 kilogram/385 pound cement block that displaces 115 liters/4 cubic feet of water lies on the bottom in 14 meters/46 feet of salt water. What is the minimum amount of water that must be displaced from lifting device to bring the block to the surface?
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4cuftx64lbscuft=256lbs; 385lbs-256lbs=129lbs; 129lbs/64lbscuft=2.01cuft
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What is the gauge pressure at 38meters/125 feet of fresh water?
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125ft/34ftatm=3.68 atm gauge pressure
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The absolute pressure in 15meters/50 feet of sea water is:
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50ft/33ftatm=1.52atm; 1.52atm+1atm=2.52atm
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If a sealed, flexible, air filled container with a volume of one liter at 20 meters/66feet is released, what will its volume be when it reaches the surface(given that it doesn’t explode)?
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1literx3ata=V2x1ata; 3litersata=V2x1ata; 3 liters=new pressure at surface
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At 40 meters/132 feet of salt water a flexible container is filled to only 1/5 of its capacity. If this container is taken to 20meters/66 feet, what will happen to the air volume inside?
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The air volume will increase by 5/3
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Approximately how much air must be pumped down from the surface to fill a 40 liter container if the container lies in 40 meters/132 feet of salt water?
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5atax40liters=200liters
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Approximately how much denser is the air a diver breathes at a depth of 20meters/66feet as compared to the surface?
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66feet/33ftata=2ata; 2ata+1ata=3 ata or 3 times as dense
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If it takes a diver 90 minutes to breathe all the air from a scuba tank at the surface, approximately how long will the air in that tank last 30 meters/99 feet?
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90minutes/4ata=22.5 minute
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If a balloon and a scuba tank are both filled with air and placed outdoors in direct sunlight on an extremely hot day, what will happen to each?
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The volume of the balloon will increase and the pressure in the tank will increase.
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At an altitude of 300meters/10,000 feet the ambient air pressure is approximately .7 ata. What is the partial pressure of nitrogen at this altitude?
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.7ata*.79=.55 ata
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If an air filled balloon is taken to a depth of 20meters/66 feet, what is the approximate partial pressure of oxygen in the balloon?
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21%*3ata=.63ata
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A scuba cylinder is accidentally filled with 1.2% carbon monoxide. Approximately what percentage of carbon monoxide will the cylinder contain if it is taken to a depth of 30meters/99 feet?
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1.2%
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If a diver breaths air that contaiins0.9% carbon monoxide at 30meters/99 feet of seawater, this would have the same physiological effect on the diver as breathing what percentage of carbon monoxide at that surface?
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3.6%
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If the ambient air pressure surrounding a liquid filled open container is quickly decreased, the amount of gas that is dissolved in the liquid will ______.
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Decrease and gas bubbles may form
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If a glass of water has been placed in a pressure pot at 1at, what will happen if the pressure is raised to 2ata?
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The gas pressure within the liquid will: increase
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Recreational scuba divers who ascend to altitude soon after completing a dive increase their risk of decompressions sickness because:
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the surrounding pressure is less than the partial pressure of nitrogen in the tissues
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