Chapter 5: Fluids and Solids Flashcards

1
Q

Fluid definition:

A

has the ability to flow and conform to the shape of the container

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2
Q

Solid definition:

A

does not flow and its rigidity helps it retain a shape independent of that of any container

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3
Q

Liquids and gases are both:

A

fluids

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4
Q

Density equation:

A

p = m/v

a scalar quantity; units = kg/m3 or g/mL or g/cm3

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5
Q

How many liters are in a cubic meter?

A

1000

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6
Q

Equation to determine the weight of any volume of a given substance:

A

W = ρVg

where p is the density and V is the volume of the substance

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7
Q

Specific gravity:

A

the ratio of the density of a substance to that of pure water at 1 atm and 4 degrees Celsius; if it is less than one the object will float; if it is greater than one the object will sink

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8
Q

Density of water:

A

1,000 kg/m3 or 1 g/cm3

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9
Q

Pressure is:

A

the force per unit of area; it is exerted by a fluid on the walls of its container and on objects placed in the fluid

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10
Q

Equation to determine pressure:

A

P = F/A

where F is the normal force and A is the area; a scalar quantity; units = Pa = N/m2

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11
Q

Pressure conversions:

A

1.013 X 105 Pa = 1 atm = 760 torr = 760 mmHg

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12
Q

Absolute pressure is:

A

the sum of all pressure at a certain point within a fluid; it is equal to the pressure at the surface of the fluid (liquid or gas) plus the pressure due to the fluid itself

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13
Q

Equation to determine absolute pressure:

A

P = Po + ρgh

where P is the absolute pressure, Po is the pressure at the surface, and ρgh is (density fluid above)(gravity)(height of submerged object below surface)

units = N/m2

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14
Q

Gauge pressure is:

A

the difference between the surface pressure and the absolute pressure

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15
Q

Equation to determine gauge pressure:

A

Pg = P - Patm = (Po + ρgh) - Patm

units = Pa

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16
Q

Forces and fluids:

A

fluids can exert perpendicular forces, but cannot withstand shear forces

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17
Q

On the MCAT, liquids are assumed to be:

A

incompressible and are ideal conservative systems

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18
Q

Forces and solids:

A

solids can exert perpendicular forces and can withstand shear forces

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19
Q

If mass is held constant in the density equation, what is the relationship between volume and density?

A

inverse

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20
Q

During thermal expansion, what happens to density and volume?

A

density decreases as volume increases

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21
Q

The pressure exerted by a gas against that walls of its container will always be:

A

perpendicular to the container walls

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22
Q

Hydrostatics is:

A

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

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23
Q

Pascal’s principle states that:

A

an applied pressure to an incompressible fluid will be distributed undiminished throughout the entire volume of the fluid; hydraulic machines operate based on this principle

24
Q

Equation of Pascal’s principle for incompressible fluids in containers:

A

P = F1/A1 = F2/A2

V = A1d1 = A2d2

W = F1d1 = F2d2

25
Area of a piston:
πr2 | (the surface of a piston is circular)
26
Equation to determine the buoyant force on a floating object:
Fbuoy = (Vfluid displaced)(pfluid)(g) = weight of the object units = (kg)(m/s2)
27
Equation to determine the buoyant force on a fully submerged object:
Fbuoy = (Vobject submerged)(pfluid)(g) units = (kg)(m/s2)
28
When an object is placed in a fluid, it will sink until:
the point at which the volume of displaced fluid exerts a force that is equal to the weight of the object
29
An object's specific gravity represented as a percentage directly indicates:
the percentage of the object's volume that is submerged in the fluid
30
The direction of buoyant force is always:
opposite the direction of gravity
31
Surface tension results from:
cohesion (the attractive force that a molecule of liquid feels toward other molecules of the same liquid)
32
Adhesion:
the attractive force a molecule of liquid feels toward the molecules of some other substance (causes a meniscus)
33
A meniscus curved upward forms when:
the adhesive forces between the liquid and the container are greater than the cohesive forces of the liquid
34
A backward meniscus forms when:
the adhesive forces between the liquid and the container are less than the cohesive forces of the liquid
35
Viscosity is:
the resistance of a fluid to flow; can be thought of as fluid friction; the higher the viscosity, the slower the flow
36
Low-viscosity fluids have low internal resistance and behave more like:
ideal fluids (which have no viscosity)
37
SI unit of viscosity:
(N)(s/m2)
38
The two types of fluid flow:
laminar (smooth and orderly) and turbulent (rough and disorderly)
39
Equation to determine the critical velocity (Vc) of a fluid flowing through a tube:
vc = NRη/ρD where NR is a given constant; η is the viscosity of the fluid, ρ is the density of the fluid, and D is the diameter of the tube units = m/s
40
Streamines:
indicate the pathway followed by fluid particles as they move; velocity vector always tangentil to streamline; streamlines never cross each other
41
For a closed system, the volumetric rate of flow is:
constant and independent of changes in cross sectional area (the amount of water flowing past a point in a given amount of time is constant regardless of the width of the tube)
42
Fluids move more quickly through --- passages and more slowly through --- passages.
more quickly through narrow passages and more slowly through wider passages (continuity equation)
43
The continuity equation:
v1A1 = v2A2 = constant (the rate of flow)
44
Bernouli's equation (an expression of conservation of energy for a flowing fluid):
P1 + 1/2ρv12 + ρgy1 = P2 + 1/2ρv22 + ρgy2
45
For horizontal flow, there is an inverse relationship between:
pressure and velocity
46
Elasticity of solids:
a measure of the response of a solid to an application of pressure; depending on the particular way in which the pressure is exerted, the object may experience a change in length, volume, or lateral displacement known as shear
47
Stress on a solid is:
a measurement of the pressure (F/A) applied to the solid
48
Strain on a solid is:
the degree to which the solid deforms under pressure
49
Equation to determine Young's Modulus (perpendicular application of force):
Y = (F/A) / (∆L/L) it gives the change in length of a solid when a pressure is applied perpendicularly to it (compression or stretching)
50
Elastic limits of a solid:
the degree to which an object can be compressed or stretched before it is permanently deformed or ruptured
51
Yield strength of a solid is:
the point of shape change beyond which a material will not return to its original dimensions once the applied force is removed
52
Ultimate strength of a solid is:
the point at which enough stress is applied to a solid object that it ruptures
53
Equation to determine Shear Modulus (parallel application of force):
S = (F/A) / (x/h) where x is the lateral displacement and h is the vertical displacement
54
In both Young's modulus and Shear modulus, the ratio is:
(stress) / (strain) stress is always represented as pressure (F/A)
55
Equation to determine Bulk modulus (chage in volume due to pressure):
B = (F/A) / (∆V/V) where V is volume
56
Relationship between the speed of sound and the Bulk modulus:
the speed of sound is proportional to the square root of the bulk modulus; sounds travel fastest through solids (highest bulk modulus) and slowest through gases (lowest bulk modulus)
57
Bernoulli's equation states the the sum of --- and --- will be constant between any two points in a closed system.
static pressure and dynamic pressure