Fluids Flashcards

1
Q

Liquid

A

ability to flow and conform to the shapes of their containers

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2
Q

Gases and liquids are….

A

Fluids

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3
Q

Only solids can withstand ____ forces, but both fluids and solids can exert _____ forces.

A

shear/tangential

perpendicular

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4
Q

Density

A

scalar

p = m/v

g/mL or kg/m^3 or g/cm^3

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5
Q

1 g/cm^3 = _____ kg/m^3

A

1000

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6
Q

Weight of any Volume

A

Fg = density * volume * gravity

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7
Q

Specific Gravity

A

density of a fluid compared to pure water @ 1 atm and 4 C

SG = density / 1(g/cm^3)

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8
Q

Pressure

A

ratio of magnitude of force per unit area in pascals

P = F/A

scalar

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9
Q

1 atm = ____ torr = _____ mmHg = 1.013*10^5 Pa

A

760

760

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10
Q

1 Pa = _____ N/m^2

A

1

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11
Q

Atmospheric Pressure

A

changes with altitude

impacts a number of processes including hemoglobins affinity for oxygen and boiling of liquids

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12
Q

Absolute (Hydrostatic) Pressure

A

total pressure exerted on an object submerged within a fluid

P = Po + pgz

Po = ambient pressure (pressure at surface)

p = density

z = depth of object

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13
Q

In open air and most situations Po = _____ but in other fluid systems the surface pressure may be higher or lower than atmospheric pressure.

A

1 atm

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14
Q

Pressure cooker increases ____ to raise the ___ of water in food to reduce cooking time and prevent loss of moisture.

A

pressure

boiling point

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15
Q

Gauge Pressure

A

difference between absolute pressure inside tire and armspheric pressure outside the tire

Pgauge = P - Patm = (Po + pgz) - Patm

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16
Q

Hydrostatics

A

study of forces and pressures acting on fluids at rest

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17
Q

Pascals Principle

A

an incompressible fluid with a change in pressure will have it transmitted through every portion of the fluid and the walls of the containing vessel

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18
Q

Hydraulic Systems

A

take advantage of the near-incompressibility of liquids to generate mechanical advantage (pascals theory)

pressure is same across both piston areas, so forces are proportional based in ratio of areas

P = F1/A1 = F2/A2

F2 = F1 (A2/A1)

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19
Q

Piston Displacement of Hydraulic systems

A

energy is conserved as volume displaced by piston 1 is equal to volume displaced in piston 2

V = A1d1 = A2d2

d2 = d1(A1/A2)

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20
Q

Work Generated by Piston Hydraulic Systems

A

W = P*delta V = F/A (Ad)

W = F1d1 = F2d2

greater force through smaller distance

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21
Q

Archimedes Principle

A

buoyancy of objects when placed in a fluid

any object placed in a fluid will cause a colume of fluid to be displaced equal to the volume of the object submerged

a body wholly/partially immersed in a fluid will be buoyed upwards by a force equal to the weight of the fluid it dispalces

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22
Q

Buoyant Force

A

mass of fluid dispersed exerts a force equal to its weight against the submerged object

F = pfluid * Vfluid displaced * g = pfluid * Vsubmerged*g

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23
Q

When an object is placed in a fluid, it will sink into the fluid only to the point at which the _________ exerts a force equal to the ________

A

volume of displaced fluid

weight of object

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24
Q

If two objects placed in a fluid displace the same volume of liquid, they will experience ________ even if the objects themselves have different masses.

A

same magnitude of buoyant force

25
Specific Gravity and how much a floating object lies below the surface
if an objects specific gravity is expressed as a percent, it indicates the percent of the objecy submerged: ie. ice density if 0.92 g/cm^3 so its specific gravity is 0.92 and 92% of it is submerged
26
A specific gravity of exactly 1 indicates that _____
100% of the object will be submerged but it will not sink
27
Surface Tension
results from cohesion molecules have strong attractive forces on the molecules below them pulling surface of the liquid toward the center to produce the tension with a net upward force.
28
Cohesion
attractive force between molecules of liquid towards other molecules of same liquid
29
Adhesion
attractive force of liquid molecules to molecules of other substance
30
Meniscus
downward curved surface which forms when adhesive forces greater than cohesive
31
Convex Meniscus
Middle higher than the edges cohesive forces greater than the adhesive forces
32
Fluid Dynamics
study of fluids in motion
33
Assumptions For Fluid Dynamics
1) rigid walled containers | 2) uniform density of fluids
34
Viscosity
resistance of a fluid to dlow Pascal-second = N*s / m^2
35
Viscous Drag
caused by increased viscosity which is a non conservative force like air resistance
36
Inviscid
fluids which have no viscosity
37
More viscous fluids will _____ more energy while flowing.
lose
38
Laminar Flow
smooth and orderly, layers of fluid flow parallel to each other; HOWEVEr layers will not always have same linear speed ie: layers close to wall of pipe flow slower than those in the center
39
Posielles Law
with Laminar Flow in a confined space, rate of flow can be calculated Q = (pi*r^4 *delta pressure gradient)/ (8 * viscosity * Length) ***relationship of radius and pressure gradient is incerse exponential to the fourth power ; even a slight change in radius can effect the pressure gradient
40
Turbulence Flow
rough and disorderly forms eddies
41
Eddies
caused by turbulence flow; swirls of fluid of varying sizes occuring downstream of an obstacle
42
Critical speed
when turbulence occurs in unobstructed fluid flow depends on physical properties of the fluid like viscosity/diameter Vc = (reynolds number * viscosity )/ (density *diamerter)
43
Boundary Layer
when critical speed is exceeded, laminar flow occurs only in fluid adjacent to the wall
44
Reynolds number
depends on size, shape and surface roughness of an objects within the fluid
45
Streamlines
pathways followed by fluid eleents/particles as they move velocity vector is tangent to the stram line and they don't cross each other
46
Flow rate is ____ for a closed system and is ____ of changes in cross sectional area
constant independent
47
Linear Speed
measure of linear displacement of fluid particles in a given amount of time
48
While the flow rate is constant, the linear speed of the fluid _______ to the cross sectional area
does not change relative
49
Continuity Equation :Q = v1A1 = v2A2
Q flow rate v1 = linear speeds A = cross sectional area tells us fluids flow more quickly through narrow passages and slowly through wider onces
50
Bernoullis Equation
P1 + 1/2pv1^2 + pgh1 = P2 + 1/2pv2^2 + pgh2 P is absolute pressure of fluid p is density of fluid v is linear speed h is heigh of fluid sum of the staatic pressure and dynamic pressure will be constant within a closed contained for an incompressible fluid not experiencing viscous drag
51
Dynamic Pressure
pressure associated with movement of fluid 1/2pv^2
52
Static pressure
P + pgh
53
Venturi Flow Meter
pgh constant at both points h difference is difference in heights of the columns linear speed must increases as cross sectional area decreases dynamic pressure increases, absolute pressure decreases making fluid at venturi tube lower
54
Circulatory system is a _____ with a _____ flow rate. The ___ flow rate can be measured as a _____
closed loop non constant non constant pulse
55
As blood flows away from the heart, each vessel has _____ resistance until the capillaries, but resistance total decreases as the vessels are ___ with each other.
increased parallel
56
Return flow of blood to heart from skeletal muscles squeezing, _____ pressure in limbs to push blood to heart which has decreased pressure
increasing
57
Results of turbulent blood flow
heart murmurs
58
During inspiration, there is a ____ pressure gradient that moves air into lungs. During expatriation this gradient reverses. When air reaches the alveoli it has ______
negative essentially no