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25 Cards in this Set
- Front
- Back
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What two forces make up dynamic fluid force?
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Drag force and lift force
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What is the relationship between drag force and lift force?
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They are always perpindicular to each other
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Define dynamic fluid force
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The force due to relative motion through a fluid
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Define drag force
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Resultant fluid force acting in opposition to the motion of an object through the fluid
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Define form drag
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Component of drag force caused by impact of fluid molecules with the object
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What characteristic of an object most affects form drag?
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Shape
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Why does form drag reduce with more streamlined shape?
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Streamline shape produces laminar flow and reduces turbulant flow
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Define surface drag
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Component of drag foce caused by friction between the fluid and the object
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What 4 factors affect surface drag?
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surface roughness, surface area, relative velocity, fluid viscosity
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What is the magnus effect?
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lift force created by spinning objects moving through a fluid
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What explains the magnus effect and how?
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Bernoulli's principle
the rotation of the object creates an area of high pressure and an area of low pressure; lift force is in direction of low pressure |
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What causes bouyant force?
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Immersion in fluid
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What is the direction of bouyant force?
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Opposes gravity
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What is the magnitude of bouyant force?
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weight of equal volume of water displaced by object
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Where does bouyant force act?
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Center of Volume
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What happens if center of volume and center of gravity are not in same place?
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torque is created, causing the object to spin
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What are the three functions of bone?
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Protection
Support Leverage |
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What is the makeup of bone?
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50% - mineral/caclium compounds = compression forces and stiffness
25% - water = compression forces 25% - collegen = tensile forces |
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What two types of bone are there?
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Cortical (compact) - 5-30% porous
Cancellous/Trabecular (spongy) - 90% porous |
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What is the equation for Youngs Modulus?
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E=sigma/epsilon
YM = stress/strain YM = (N/m2)/((L-Lo)/Lo) |
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What is the definition for Young modulus and what are the units?
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Intrinsic stiffness (Pascals, Pa)
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What is the relationship between bone density and the magnitude of the force placed on the bone?
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Directly proportional
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What kinds of things increase osteoblast activity?
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Some sports like tennis
Load bearing exercises, especially high magnitude |
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Define osteopenia
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decreased bone mineral density
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What are the factors of maximum muscle force production?
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Cross-sectional area
frequency of firing # of mf recruited type of mf recruited contraction velocity muscle design (series vs parallel - pennate angle) Fiber length |
