FLUIDS AND SOLIDS
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| Which have intermolecular bonds (s,l,g)? | solids and liquids
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| WHat can withstand perpendicular forces? | gases, liquids, solids
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| What can withstand parallel forces? | solids
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| specific gravity (2) | 1.) p = p(material) / p(water) at 4C
2.) Weight / buoyant force
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| Pascal's principle | Pressure applied to enclosed fluid is transmitted equally throughout an incompressible fluid and walls of container
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| Pascal's Equation | P1-P2 = p(y2-y1)g
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| Total Pressure Equation | P(total) = P(atm) + pgh
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| When a fluid comes to rest, what forces does it experience? | normal force and gravity
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| What are extensive properties? | change with quantity of substance (mass and energy)
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| What are intensive properties? | do not change with quantity of substance (density and pressure)
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| What are incompressible and have constant density? | liquids and solids
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| Does a bucket or cup of water have a greater density? | NEITHER
-mass refers to inherent mass
-liquids are incompressible
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| Why does density of gas change? | gases are compressible --> change volume --> change density
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| 2 densities of water | p = 1000 kg/m^3
p = 1 gm / cm^3
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| What is fluid pressure? | measure of the KE due to random velocities of molecules within a fluid distributed over fluid volume
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| Relate Patm and Pascals | P(atm) = 101,000 Pa
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| Does Pascal's Principle apply to gases? | NO --> gases are compressible
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| Does the shape of a container affect fluid pressure? | NO --> fluid pressure is a function of depth
-pressure everywhere at a given depth in same resting fluid is constant
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| Does an ideal machine ever change work? | NO
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| 2 equations for Hydraulic Lift? | F1d1 = F2d2
F1/A1 = F2/A2
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| What does a sunken object displace? | volume of fluid equal to its own volume
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| What does a floating object displace? | volume of fluid equal to its own weight
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| When an object is sunk, what forces act on it? | buoyant force and normal force
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| What does buoyant force equal to for a floating object? | p(medium) * V(displaced) * g
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| What does weight equal to for a floating object? | p(object) * V (object) * g
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| How are weight and buoyant force related for a floating object? | W = B
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| How to calculate percent submerged for a floating object? | Relative densities = percent submerged
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| V(object) > V (displaced) for what? | floating object
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| What is apparent weight? | Normal force
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| What does buoyant force equal to for a sunken object? | p (medium) * V (object) *g
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| What does weight equal to for a sunken object | p (object) * V (object) *g
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| How do weight and buoyant force relate to density for sunken object? | weight / buoyant force = p(object) / p(medium)
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| Under what conditions of volume and density will an object float? | V(object) > V (displaced)
p(object) < p(medium
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| Under what conditions of weight, buoyant force, and density will an object sink? | W > B
p(object) > p(medium)
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| What IMF account for surface tension? | H-bonds or Van der Waals
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| Water vs. ethanol: which will evaporate first / which will condense first? | -ethanol
-water
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| What happens with surface tension increases? | SA decreases, volume stays the same, spherical shape, evaporate less
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| Cohesion | attraction between same molecules
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| adhesion | attraction between different molecules
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| What is viscous force? | -fluid flowing through pipe experiences forward and opposing frictional force
-measure of fluids resistance to forces not perpendicular to surface
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| In a pipe, where is the fluid the fastest? Slowest? | center
near edges of pipe
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| Increase temperature of fluid, what happens to viscosity of liquid and gas? | liquid viscosity decreases, gas viscosity increases
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| Flow Rate | Volume of fluid that passes through a pipe per unit time
--> different from flow speed of a fluid
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| Poiseuille's Principle | Q = pi*r^4 / 8nL (P1-P2)
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| What does high BP mean in relation to Poiseuille's Principle? | Heart is generating a large P1 to produce necessary Q to get blood to tissue
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| Continuity equation | A1V1 = A2V2
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| Why does fluid flow? | flows from region of high pressure to low pressure
-->more precisely direction of fluid flow is fluid's tendency to find greatest entropy
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| What work is done on fluid? | pressure difference pushing fluid in one direction
W = deltaKE + deltaPE
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| Bernoulli's Equation | P1 + 1/2pv^2 + pgy1 = P2 + 1/2pv^2 + pgy2
--> think conservation of energy!
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| What happens to pressure when there is higher velocity? | Pressure decreases
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| How to increase turbulence? (density, avg velocity, radius) | increase density, average velocity, and radius of vessel
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| Does buoyant force change with depth? | NO --> due to difference in pressure only between upper and lower surfaces
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| What kind of motion can molecules in a moving fluid thought to have? | 1.) random translational motion (contributes to fluid pressure for fluid at rest)
2.) uniform translational motion (does not contribute to fluid pressure)
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| Ideal Fluid (4 characteristics) | 1.) No viscosity
2. ) incompressible --> uniform density
3.) no turbulence
4.) irrotational flow
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| What is turbulence? | at any point in fluid, velocity may vary with time
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| Why does pressure decrease when velocity increases? | uniform translational KE is achieved by borrowing energy from random translational KE
--> pressure goes down
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| What happens to pressure when you increase cross-sectional area? | increases
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| What happens to pressure when you decrease cross-sectional area? | decreases
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| What creates drag? | narrow and long pipe
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| Does narrowing a pipe increase velocity for ideal and non-ideal fluid? | YES --> less effect on non-ideal because of drag
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| Why does pressure decrease when cross-SA decreases? | A1V1 = A2V2
-faster velocity --> less opportunity to interact with walls of vessel
-lower pressure
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| What does surface tension depend on? | IMF and temperature of fluid
-higher temp, weaker surface tension
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| For capillary action, which way is the water pulled when adhesive forces stronger? | upward
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| For capillary action, which way is water pulled when cohesive forces are stronger? | downward
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| What is stress? | Stress = Force / Area
-Force applied to object / area force is applied
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| What is strain? | Strain = change in dimension / original dimension
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| Modulus of elasticity | stress/ strain
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| What is yield point? | maximum stress point
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| WHat happens beyond yield point? | object will remain intact but will not regain original shape
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| What are the three moduli? | 1.) Young's Modulus (tensile stress) - E
2.) Shear's Modulus (shear stress) - G
3.) Bulk modulus (compression and expansion) - B
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| Young's Modulus | E = F/A // change in height / original height
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| Shear Modulus | G = F/A // change in x / original height
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| Bulk Modulus | B = change in Pressure // change in volume / original volume
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| What does density vary with? | temperature and pressure
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| What does buoyant force equal to for object immersed in a fluid? | weight of the fluid displaced by the object
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| What does it mean for something to be floating? | weight = buoyant force
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| What are the forces that act on an object floating in water | -weight and Fb in vertical direction
-pressure perpendicular to all surfaces
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| Speed of flow rate for a fluid is directly / inversely proportional to cross - SA | inversely proportional
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| Items with the same volume experience the same ___ | buoyant force
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| How to calculate percent submerged? | density object / density medium
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| Calculate specific gravity with weight and Fb? | specific gravity = weight / Fb
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| Surface tension is an attractive / repulsive force? | attractive
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| Within a pipe, where does fluid flow the slowest? fastest? | edge of pipe / center of pipe
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| Greater flow rate is associated with? | a greater pressure differential
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| According to Poiseuille's Principle, what are the main things to know? | -Q = r^4
-Q = 1 / L
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| In a pipe, a lower area has a faster/slower speed while a bigger area has a faster/slower speed? | slower / faster
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| does fluid flow faster or slower through a narrowed pipe? What happens to pressure? | faster / decreases
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| Are narrow or wider paths more likely to encounter turbulence? | wider
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| What does flow rate depend on? | pressure differential
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| Elasticity progression. | Elastic limit --> ultimate tension strength --> fracture
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| What are brittle materials? | materials that have ultimate tension strengths close to fractures
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| What are ductile materials? | materials that have ultimate tension strengths far from fractures
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| Does a thicker or thinner rope increase / decrease stretching length of the rope? | increase
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| What is a large bulk modulus associated with? | solid that is difficult to deform and compress
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| What is a large tensile modulus associated with? | something that requires a lot of force to stretch
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| What is a large shear modulus associated with? | something that requires a lot of force to shear
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| Comparing two objects with different masses but same volume, which will have the stronger buoyant force? | bigger mass one
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| volume of an object submerged = | volume of fluid displaced by object
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| Relate pressure, force, area | P = F / A
--> F1 / A1 = F2 / A2
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| TRUE / FALSE: In a hydraulic system, the work done on one end is different than the work output at the other. | FALSE
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| Gauge pressure | pgh
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| TRUE / FALSE: Volume flow rate of a fluid is constant | TRUE
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| Does turbulence occur at low or high velocities? | high
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| Out of solids, liquids, gases, which are compressible? | gases
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| What is shear angle? | tan-1(change in x / height)
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| When an object floats, the ratio of densities of object / medium is =? | percent submerged
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| What is the magnitude of the weight equal to in relation to the apparent weight and buoyant force? | weight = apparent weight + buoyant force
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| Relative densities for floating vs. submerged object? | percent submerged vs. W/B ratio
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| Greater viscosity requires...? | greater pressure differential
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| What does buoyant force also equal to? What does normal force equal to? | apparent weight loss / apparent weight
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| What phases are held together by IMF? | solids and liquids
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| What phases can withstand perpendicular forces? | solid, liquid, gas
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| What phase can withstand forces NOT perpendicular? | solid
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| What phase experiences large changes in density? | gas
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| When air resistance is negligible, is projectile motion independent of mass? | YES
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| What are the 2 densities of water? | 1000kg/m^3
1g/cm^3
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| What depth of water creates 1 at of pressure? | 10 m
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