In this blog you will find the correct answer of the Coursera quiz Materials Science 10 Things Every Engineer Should Know Quiz mixsaver always try to brings best blogs and best coupon codes
Thing 1
1.
Question 1
The first three categories introduced in this segment (metals, polymers,
and ceramics) are based on the three types of primary bonding: metallic, ________, and ionic, respectively.
1 point
- secondary
- covalent
- van der Waals
2.
Question 2
Glasses are considered a category separate from ceramics because their
chemistry is different, even though their atomic structure is the same.
1 point
- True
- False
3.
Question 3
Fiberglass is a good example of a ___________ combining the strength and stiffness of reinforcing glass fibers with the ductility of the polymeric matrix.
1 point
- composite
- semiconductor
- ceramic
4.
Question 4
Semiconductors are considered a category separate from
metals because their electrical conductivity is different.
1 point
- True
- False
5.
Question 5
The relationship between atomic bonding and the elastic modulus or stiffness of a metal is an example of how structure (atomic-level in this case) leads to _____________.
1 point
- properties
- breakage
- permanent deformation
Thing 2
1.
Question 1
Aluminum metal is an example of a ______________.
1 point
body-centered cubic crystal structure
face-centered cubic crystal structure
simple cubic crystal structure
2.
Question 2
The vacancy and the interstitial are two common types of point defects in metallic crystal structures.
1 point
True
False
3.
Question 3
The Arrhenius relationship shows that the rate of chemical reactions increases _______________ temperature.
1 point
with the fourth power of
linearly with
exponentially with
4.
Question 4
The Arrhenius plot is a linear set of data points in which the logarithm of rate is plotted against the ____________.
1 point
temperature in °C
inverse temperature in K-1
absolute temperature in K
5.
Question 5
The activation energy, Q, for a chemical
reaction is indicated by the _______________ of the Arrhenius plot.
1 point
slope
intercept at 1/T = 1
intercept at 1/T = 0
6.
Question 6
The gas constant, R, is equal to _______________ times the Boltzmann’s constant, k.
1 point
Avogadro’s number
1024
10-24
7.
Question 7
The gas constant, R, is an appropriate
term for equations describing gas phases and ________________ processes.
1 point
no other
all other
solid-state
8.
Question 8
The energy needed to produce a single
vacancy, Ev, is the same as the activation energy, Q.
1 point
True
False
9.
Question 9
Solid-state diffusion occurs in the face
centered cubic structure of aluminum by individual aluminum atoms hopping into
_______________ sites.
1 point
adjacent interstitial
adjacent occupied
adjacent vacant
10.
Question 10
As an indication of how “close packed” the aluminum (FCC) crystal structure is, ________ of the volume of the unit cell is occupied by the aluminum atoms.
1 point
74%
68%
70%
11.
Question 11
The diffusion coefficient is defined by _______________.
1 point
Fick’s third law
Fick’s first law
Fick’s second law
12.
Question 12
The diffusivity (D) of copper in a brass alloy is 10-20 m2/s
at 400 °C. The activation energy for copper diffusion in this system is 195
kJ/mol. The diffusivity at 600 °C is _____________.
1 point
2.93 x 10-16 m2/s
5.86 x 10-17 m2/s
2.93 x 10-17 m2/s
Thing 3
1.
Question 1
An edge dislocation corresponds to an extra ______________.
1 point
half-plane of atoms
full plane of atoms
cluster of atoms
2.
Question 2
An edge dislocation is a linear defect with the
Burgers vector _______________ to the dislocation line.
1 point
perpendicular
at a 45 degree angle
parallel
3.
Question 3
Crushing an empty soda can made of aluminum alloy is an example of ______________.
1 point
viscous deformation
elastic deformation
plastic deformation
4.
Question 4
Plastic deformation by dislocation
motion is a ___________ alternative to deforming a defect-free crystal
structure.
1 point
stress-free
low-stress
high-stress
Thing 4
1.
Question 1
The first of the “big four” mechanical
properties obtained in the tensile test is ___________________.
1 point
tensile strength
elastic modulus
yield strength
2.
Question 2
The tensile strength is ___________ the
yield strength for typical metal alloys.
1 point
less than
greater than
about the same as
3.
Question 3
The ductility corresponds to the ______________.
1 point
strain at failure
total amount of elastic deformation
strength at failure
4.
Question 4
The Elastic Modulus is given by ______________.
1 point
Ohm’s Law
Poisson’s ratio
Hooke’s Law
5.
Question 5
The yield strength corresponds to ______________.
1 point
the point of tangency where plastic deformation first begins
an offset of 0.2%
an offset of 0.1%
6.
Question 6
The stress versus strain curve shows that a metal alloy becomes weaker beyond the tensile strength.
1 point
True
False
7.
Question 7
The elastic “snap back” that occurs at failure is parallel to ______________.
1 point
the strain axis
the stress axis
the elastic deformation portion of the stress-strain curve.
8.
Question 8
The Toughness or work-to-fracture is the total area under the stress versus strain curve.
1 point
True
False
Thing 5
1.
Question 1
“Creep” deformation describes the
behavior of materials being used at high temperatures under high pressures over
_____________ time periods.
1 point
long
short
intermediate
2.
Question 2
We added comments about polymers because their weak, secondary bonding between long chain molecules causes them to exhibit creep deformation at relatively low temperatures.
1 point
True
False
3.
Question 3
In the simplest sense, the creep test is
essentially a tensile test done at a high temperature under ____________ load.
1 point
no
a variable
a fixed
4.
Question 4
A linear portion of the strain versus time plot corresponds to the ______________ stage of the overall creep curve.
1 point
secondary
tertiary
primary
5.
Question 5
The strain rate in the ______________ stage of the creep test is analyzed using the Arrhenius equation, analogous to our previous discussion of the diffusion coefficient.
1 point
tertiary
primary
secondary
6.
Question 6
A powerful use of the Arrhenius relationship is to measure creep data at low temperatures and then extrapolate the data to high temperatures, allowing us to predict the performance there.
1 point
True
False
7.
Question 7
In a laboratory creep experiment at
1,000 °C, a steady-state creep rate of 5 x 10-1 % per hour is
obtained for a metal alloy. The activation for creep in this system is known to
be 200 kJ/mol. We can then predict that the creep rate at a service temperature
of 600 °C will be ______________. (We can assume the stress on the sample in
the laboratory experiment is the same as at the service temperature.)
1 point
4.34 x 10-5 % per hour
80.5 x 106 % per hour
8.68 x 10-5 % per hour
8.
Question 8
For high temperature creep deformation in ceramic materials, a common mechanism is ______________.
1 point
dislocation climb
viscous flow (molecules sliding past one another)
grain boundary sliding
Thing 6
1.
Question 1
The ductile-to-brittle transition was first discovered in conjunction with the failure of ______________.
1 point
the Queen Mary
the Titanic
Liberty Ships
2.
Question 2
The impact energy is an indicator of
whether a fracture is ductile or brittle, as measured by the ____________ test.
1 point
creep
Charpy
tensile
3.
Question 3
Although they have equally high atomic
packing densities, face-centered cubic (fcc) metals with more slip systems are
typically ductile while hexagonal close packed (hcp) metals are relatively __________.
1 point
strong
brittle
weak
4.
Question 4
Body-centered cubic (bcc) alloys such as
low-carbon steels demonstrate the ductile-to-brittle transition because their
dislocation motion tends to be ___________ than that in the more densely packed
fcc alloys.
1 point
faster
slower
more erratic
Thing 7
1.
Question 1
We focus on “critical flaws” that ______________.
1 point
lead to catastrophic failure
are larger than 1 mm in size
are larger than 1 μm in size
2.
Question 2
We use the example of __________________
to illustrate concern about a famous “critical flaw.”
1 point
Liberty Ships
the Liberty Bell
the Hindenburg
3.
Question 3
The design plot is composed of two intersecting segments: yield strength corresponding to general yielding and fracture toughness corresponding to ______________.
1 point
fracture following multiple stress applications
high-temperature fracture
flaw-induced fracture
4.
Question 4
The design plot shows stress as a function of time.
1 point
True
False
5.
Question 5
The ______________ flaw size is defined
within the design plot at the intersection between the general yielding segment
and the flaw-induced fracture segment.
1 point
critical
maximum
minimum
6.
Question 6
The I in the subscript of the
fracture toughness, KIc , refers to ______________ .
1 point
mode I (uniaxial tensile) loading
the primary stage of creep deformation
“i” for incremental loading
7.
Question 7
The stress versus strain curve for a sample with a critical pre-existing
flaw looks like ______________.
1 point
a regular stress versus strain curve but with a lower value of Y.S.
that of a brittle ceramic
a regular stress versus strain curve but with a higher value of Y.S.
8.
Question 8
The benefit of failure by general yielding is that ______________.
1 point
the failure occurs quickly
the plastic deformation serves as an early warning
the structure does not deform permanently
9.
Question 9
“Flaw-induced fracture” is also known as “catastrophic fast fracture.”
1 point
True
False
Thing 8
1.
Question 1
The fatigue strength that is associated with catastrophic failure after
a large number of stress cycles is ______________ the yield strength.
1 point
less than
greater than
about the same value as
2.
Question 2
A metal alloy known to have good
ductility is used in the manufacture of a spring in a garage door assembly. The
spring breaks catastrophically in its first use, under a load known to
correspond to about 2/3 of the alloy’s yield strength. This is a good example
of fatigue failure.
1 point
True
False
3.
Question 3
The fatigue curve is a plot of breaking stress versus ______________.
1 point
the number of stress cycles
time
temperature
4.
Question 4
The “fatigue strength” is defined as the point where
the fatigue curve reaches a value of roughly _____________ of the tensile
strength.
1 point
10%
75%
one-fourth to one-half
5.
Question 5
Fatigue is the result of a critical flaw built up ______________.
1 point
instantly
prior to being put into service
after a large number of stress cycles
6.
Question 6
The relationship of fatigue to the
design plot (introduced in our discussion of fracture toughness) is that we
grow the size of a flaw at a relatively low stress until the flaw size reaches
the “flaw-induced fracture” segment of the design plot.
1 point
True
False
Thing 9
1.
Question 1
We begin by focusing on making things
slowly. Phase diagrams are maps that help us track microstructural development
during the slow cooling of an alloy. The Sn-Bi phase diagram is an example of a
______________ diagram.
1 point
temperature versus time
eutectoid
eutectic
2.
Question 2
The phases in a two-phase
region of the phase diagram are determined by the adjacent, single phases on
either side of that two-phase region.
1 point
True
False
3.
Question 3
In the important Fe – Fe3C
(iron carbide) phase diagram, steel making is described by slow cooling through
the ______________ reaction.
1 point
melting
eutectic
eutectoid
4.
Question 4
The “pasty” quality of lead solders in the lead-tin system can be
attributed to ______________.
1 point
the fact that lead has a higher melting point than tin
the nature of the two-phase liquid + α solid solution region
the nature of the two-phase α solid solution + β solid solution
region
5.
Question 5
Heat treatment can be
defined as the time-independent process of producing a desired microstructure.
1 point
True
False
6.
Question 6
Previously (in Thing 2), we saw that diffusion increases as temperature
increases. Instability ______________ as temperature decreases.
1 point
decreases
stays about the same
increases
7.
Question 7
Because of the competition between instability and diffusion, the most rapid
transformation will occur _______________.
1 point
above the transformation temperature
at the transformation temperature
below the transformation temperature
8.
Question 8
The “knee-shaped” curve of the TTT diagram for
eutectoid steel is a good example of the competition between instability and ______________.
1 point
radioactivity
diffusion
stability
9.
Question 9
As we monitor the TTT diagram for
eutectoid steel through the diffusional transformation region, we see that the
decreasing magnitude of diffusivity with decreasing temperature leads to
______________.
1 point
increasingly finer microstructures
increasingly more coarse microstructures
generally unchanged grain sizes
10.
Question 10
As we continue to go to lower temperatures in the TTT diagram for
eutectoid steel, the diffusionless transformation to form martensite is the
result of ______________.
1 point
increasingly rapid atomic mobility
the domination of instability
freezing temperatures
Thing 10
1.
Question 1
The discovery of the electron in 1897 was followed by the invention of
the transistor in _________.
1 point
1937
1947
1957
2.
Question 2
Since the development of the integrated circuit in 1971, Moore’s Law has
correctly predicted that the number of transistors on a semiconductor “chip”
should double about every ____ years.
1 point
four
two
five
3.
Question 3
Electronic conduction in a semiconductor is the result of the promotion
of an electron from the conduction band up to the valence band.
1 point
True
False
4.
Question 4
The “2” that appears in the exponent of the Arrhenius equation for an
intrinsic semiconductor is ______________.
1 point
derived from the fact that each electron promotion produces two carriers – an electron and an electron hole (in the valence band)
a typographical error
derived from the ideal gas law
5.
Question 5
An extrinsic semiconductor is one
with a small amount of purposefully added impurity or “dopant.”
1 point
True
False
6.
Question 6
The slope of the Arrhenius plot for an
extrinsic semiconductor is ______________ that for the corresponding pure or
undoped material.
1 point
greater than
less than
about the same
7.
Question 7
Combining the extrinsic behavior with the intrinsic on the Arrhenius
plot produces ______________.
1 point
no effect, given the different nature of conductivity in the two
cases
a stable level of conductivity over a range of temperatures
a doubling of the conductivity
Ten Things Final
1.
Question 1
The first three categories introduced in
the opening of the course (metals, polymers, and ceramics) are based on the
three types of primary bonding: metallic, covalent, and ____________,
respectively.
1 point
hydrogen
van der Waals
ionic
2.
Question 2
In illustrating the relationship between
atomic structure and the elastic modulus or stiffness of a metal (structure
leads to properties!), we saw how elastic deformation follows from the
stretching of atomic ___________.
1 point
bonds
weights
energy
3.
Question 3
The _________ plot is a linear set of data points in
which the logarithm of rate is plotted against the inverse of absolute
temperature in K-1.
1 point
Arrhenius
fatigue
TTT
4.
Question 4
In the face centered cubic
structure of aluminum, solid-state diffusion occurs by individual aluminum
atoms hopping into adjacent interstitial sites.
1 point
True
False
5.
Question 5
___________________ is a linear defect with the
Burgers vector perpendicular to the dislocation line.
1 point
A vacancy
An edge dislocation
An interstitial
6.
Question 6
Consider the body of an automobile made
of steel. A small dent in that structure when the automobile is accidentally
driven into a barrier is an example of _________ deformation.
1 point
plastic
elastic
viscous
7.
Question 7
In the tensile test, the yield strength
(Y.S.) is found just beyond the linear elastic region (which gives the elastic
modulus, E) at an offset of 0.2%
strain.
1 point
True
False
8.
Question 8
Beyond the tensile strength (T.S.), the
maximum stress value measured over the range of the tensile test, we measure the
ductility corresponding to the total amount of ______________ deformation.
1 point
elastic
plastic
elastic + plastic
9.
Question 9
For high temperature creep deformation
in metal alloys, a common mechanism that we illustrated is ______________.
1 point
grain boundary sliding
viscous flow (molecules sliding past one another)
dislocation climb
10.
Question 10
A powerful use of the Arrhenius relationship is to
measure creep data at high temperatures over conveniently short time periods
and then extrapolate the data to __________ temperatures, allowing us to
predict the performance of the material over long operating times.
1 point
low
cryogenic
even higher
11.
Question 11
The impact energy is the standard property for monitoring the ductile-to-brittle transition. The impact energy is commonly measured by means of the ______________.
1 point
tensile test
creep test
Charpy test
12.
Question 12
Body-centered cubic (bcc) alloys tend to
exhibit the ductile-to-brittle transition because they have fewer slip systems
than in the ductile face-centered cubic (fcc) alloys.
1 point
True
False
13.
Question 13
The design plot is composed of two
intersecting segments: yield strength corresponding to ___________ and fracture
toughness corresponding to flaw-induced fracture.
1 point
high-temperature fracture
general yielding
fracture following multiple stress applications
14.
Question 14
The design plot monitors stress as a function of ______________.
1 point
time
flaw size, a.
strain
15.
Question 15
A metal alloy known to have good
ductility is used in the manufacture of a spring in a garage door assembly. The
spring breaks catastrophically after 10 years of regular use, under a load known
to correspond to about one half of the alloy’s yield strength. This is a good
example of fatigue failure.
1 point
True
False
16.
Question 16
The relationship of fatigue to the design
plot (introduced in our discussion of fracture toughness) is that we grow the
size of a flaw at a relatively low stress until the flaw size reaches the ______________
segment of the design plot.
1 point
yield stress
general yielding
flaw-induced fracture
17.
Question 17
Phase diagrams are maps that help us track
microstructural development during the slow cooling of an alloy. The Fe-Fe3C
(iron carbide) phase diagram is an example of a ______________ diagram, with
special relevance to steelmaking.
1 point
eutectoid
eutectic
temperature versus time
18.
Question 18
Quenching a eutectoid steel below about 200
°C initiates the formation of martensite because the _______________ the
austenite phase has become too great.
1 point
diffusion of carbon within
instability of
specific volume of
19.
Question 19
Electronic conduction in an _____________
semiconductor is the result of the promotion of an electron from the valence
band up to the conduction band across an energy band gap.
1 point
extrinsic
eccentric
intrinsic
20.
Question 20
Combining the extrinsic behavior with
the intrinsic on the Arrhenius plot produces a stable level of conductivity at ______________
temperatures.
1 point
relatively low
relatively high
intermediate
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