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Fluids Flashcards

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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
Q

Specific Gravity and how much a floating object lies below the surface

A

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
Q

A specific gravity of exactly 1 indicates that _____

A

100% of the object will be submerged but it will not sink

27
Q

Surface Tension

A

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
Q

Cohesion

A

attractive force between molecules of liquid towards other molecules of same liquid

29
Q

Adhesion

A

attractive force of liquid molecules to molecules of other substance

30
Q

Meniscus

A

downward curved surface which forms when adhesive forces greater than cohesive

31
Q

Convex Meniscus

A

Middle higher than the edges

cohesive forces greater than the adhesive forces

32
Q

Fluid Dynamics

A

study of fluids in motion

33
Q

Assumptions For Fluid Dynamics

A

1) rigid walled containers

2) uniform density of fluids

34
Q

Viscosity

A

resistance of a fluid to dlow

Pascal-second = N*s / m^2

35
Q

Viscous Drag

A

caused by increased viscosity which is a non conservative force like air resistance

36
Q

Inviscid

A

fluids which have no viscosity

37
Q

More viscous fluids will _____ more energy while flowing.

A

lose

38
Q

Laminar Flow

A

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
Q

Posielles Law

A

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
Q

Turbulence Flow

A

rough and disorderly

forms eddies

41
Q

Eddies

A

caused by turbulence flow; swirls of fluid of varying sizes occuring downstream of an obstacle

42
Q

Critical speed

A

when turbulence occurs in unobstructed fluid flow

depends on physical properties of the fluid like viscosity/diameter

Vc = (reynolds number * viscosity )/ (density *diamerter)

43
Q

Boundary Layer

A

when critical speed is exceeded, laminar flow occurs only in fluid adjacent to the wall

44
Q

Reynolds number

A

depends on size, shape and surface roughness of an objects within the fluid

45
Q

Streamlines

A

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
Q

Flow rate is ____ for a closed system and is ____ of changes in cross sectional area

A

constant

independent

47
Q

Linear Speed

A

measure of linear displacement of fluid particles in a given amount of time

48
Q

While the flow rate is constant, the linear speed of the fluid _______ to the cross sectional area

A

does not change relative

49
Q

Continuity Equation :Q = v1A1 = v2A2

A

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
Q

Bernoullis Equation

A

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
Q

Dynamic Pressure

A

pressure associated with movement of fluid

1/2pv^2

52
Q

Static pressure

A

P + pgh

53
Q

Venturi Flow Meter

A

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
Q

Circulatory system is a _____ with a _____ flow rate.

The ___ flow rate can be measured as a _____

A

closed loop

non constant

non constant

pulse

55
Q

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.

A

increased

parallel

56
Q

Return flow of blood to heart from skeletal muscles squeezing, _____ pressure in limbs to push blood to heart which has decreased pressure

A

increasing

57
Q

Results of turbulent blood flow

A

heart murmurs

58
Q

During inspiration, there is a ____ pressure gradient that moves air into lungs. During expatriation this gradient reverses.

When air reaches the alveoli it has ______

A

negative

essentially no

Physics (4 decks)

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