Fluids

Question 1

substances that have the ability to flow and conform to the shape of their containers; can exert perpendicular forces but not shear; liquids and gases are considered this

Answer 1

fluids

Question 2

do not flow and they retain their shape regardless of their containers

Answer 2

solids

Question 3

mass per unit volume of a substance

Answer 3

density (ρ)

Question 4

density (ρ)

Answer 4

ρ = m/V

Question 5

measure of force per unit area; it is exerted by a fluid on the walls of its container and on objects placed in fluid; scalar quantity; gas always exerts perpendicular to walls of container

Answer 5

pressure

Question 6

pressure

Answer 6

P = F/A

Question 7

sum of all pressures at a certain point within a fluid; equal to pressure at surface of a fluid (usually atmospheric) plus pressure due to fluid itself

Answer 7

absolute pressure

Question 8

absolute pressure

Answer 8

P = P(o) + ρgz

where:
P(o) = incident/ambient pressure (at surface)
ρ = density
g = acceleration due to gravity
z = depth of object

Question 9

difference between absolute pressure and atmospheric pressure

Answer 9

gauge pressure

Question 10

gauge pressure

Answer 10

P(gauge) = P - P(atm) = (P(o) + ρgz) - P(atm)

where:
P(o) = incident/ambient pressure (at surface)
ρ = density
g = acceleration due to gravity
z = depth of object below some point

Question 11

the study of fluids at rest and the forces and pressures associated with standing fluids

Answer 11

hydrostatics

Question 12

states that a pressure applied to an incompressible fluid will be distributed undiminished throughout the entire volume of the fluid

Answer 12

Pascal’s principle

Question 13

operate based on the application of Pascal’s principle to generate mechanical advantage

Answer 13

hydraulic machines

Question 14

principle that governs buoyant force

Answer 14

Archimede’s principle

Question 15

when an object is placed in a fluid, the fluid generates a force against the object that is equal to the weight of the fluid displaced by the object; direction is always opposite to the direction of gravity

Answer 15

buoyant force

Question 16

when max force is larger than force of gravity on object the object will _____; true if object is less dense than fluid it is in

Answer 16

will float

Question 17

when max force is smaller than force of gravity on object the object will _____; true if object is more dense than fluid it is in

Answer 17

will sink

Question 18

causes liquid to form a thin but strong layer at liquid’s surface, caused by cohesion

Answer 18

surface tension

Question 19

attractive force that a molecule of liquid feels toward other molecules of the same liquid

Answer 19

cohesion

Question 20

attractive force that a molecule of liquid feels toward the molecules of some other substance

Answer 20

adhesion

Question 21

the study of fluids in motion

Answer 21

fluid dynamics

Question 22

a measurement of a fluid’s internal friction

Answer 22

viscosity (η)

Question 23

a nonconservative force generated by viscosity; analogous to air resistance

Answer 23

viscous drag

Question 24

smooth and orderly flow of fluid; often modeled as layers of fluid that flow parallel to one another, layers will not have same linear speed

Answer 24

laminar flow

Question 25

relationships that determine rate of laminar flow

Answer 25

Poiseuille’s law

Question 26

Poiseuille’s law

Answer 26

Q = (π (r^4) ΔP) / (8ηL)

where:
Q = flow rate
r = radius of tube
ΔP = pressure gradient
η = viscosity
L = length of pipe

Question 27

rough and disorderly flow of fluid; when unobstructed, turbulence can arise when the speed of the fluid exceeds a certain critical speed

Answer 27

turbulent flow

Question 28

critical speed (V(c))

Answer 28

V(c) = (N(R) η) / (ρD)

where:
N(R) = Reynold's number
η = viscosity
ρ = density
D = diameter of tube

Question 29

volume per unit time; is constant for a closed system and independent of changes in cross-sectional area

Answer 29

flow rate

Question 30

measure of linear displacement of fluid particles in a given amount of time; does change relative to ross-sectional area

Answer 30

linear speed

Question 31

expression of conservation of mass; tells us that fluids will flow more quickly through narrow passages and more slowly through wider ones

Answer 31

continuity equation

Question 32

continuity equation

Answer 32

Q = v(1) * A(1) = v(2) * A(2)

where:
Q = flow rate
v = linear speed
A = cross-sectional area

Question 33

an expression of conservation of energy; states that sum of static pressure and dynamic pressure will be constant between any two points in a closed system

Answer 33

Bernoulli’s equation

Question 34

Bernoulli’s equation

Answer 34

P(1) + 1/2 ρv(1)^2 + ρgh(1) = P(2) + 1/2 ρv(2)^2 + ρgh(2)

where:
P = absolute pressure
ρ = density
v = linear speed
g = acceleration due to gravity
h = height of fluid above some point

Question 35

term of Bernoulli’s equation associated with movement; kinetic energy divided by volume

Answer 35

dynamic pressure

Question 36

dynamic pressure

Answer 36

1/2 ρv^2

Question 37

term of Bernoulli’s equation that is same as equation for absolute pressure: ambient pressure + (potential energy / volume)

Answer 37

static pressure

Question 38

static pressure

Answer 38

P + ρgh

Question 39

refers to how the velocity of a fluid passing through a constricted area will increase and its static pressure will decrease

Answer 39

Venturi effect

Question 40

behaves as a closed system with nonconstant flow in the body; is a closed loop

Answer 40

circulatory system

Question 41

decreases as total cross-sectional area increases

Answer 41

resistance

Question 42

primary driver of arterial circulation

Answer 42

heart

Question 43

has three times the volume of arterial circulation and is motivated by the skeletal musculature and expansion of the heart

Answer 43

venous circulation

Question 44

_____ and _____ create a pressure gradient not only for the respiratory system, but for the circulatory system as well

Answer 44

inspiration and expiration

Question 45

air that has essentially zero speed in the body

Answer 45

air at the alveoli