MSE 2001 Final Exam
Based on the classroom discussion, select the best description for the discipline of materials science and engineering (MSE). a) MSE both discovers new physical phenomena about materials and designs new engineering materials using these phenomena b) MSE both discovers new engineering components (ex: turbines, crankshafts, etc.) and designs new systems with these components (ex: aircrafts and vehicles) c) MSE designs new engineering systems d) MSE discovers new physical phenomena in materials
a) MSE both discovers new physical phenomena about materials and designs new engineering materials using these phenomena
Magnetization-Magnetic Field data for 4 different materials is reported in the figure shown here. Which of these materials is the "softest" magnetic material: a) Material A b) Material B c) Material C d) Material D e) Materials B and D will perform equally well for this application
a) Material A
What is the energy barrier to diffusion? a) The energy barrier to diffusion is the energy cost of breaking bonds and disrupting the position of neighboring atoms to "squeeze" the diffusing atom from one site to another site. b) The energy barrier to diffusion is the energy cost of atoms vibrating faster to push an atom from one site to another site. c) The energy barrier to diffusion is the energy cost of entropically mixing all of the atoms up when they diffuse. d) Diffusion doesn't have an energy barrier, it is an athermal ("non-thermal") process.
a) The energy barrier to diffusion is the energy cost of breaking bonds and disrupting the position of neighboring atoms to "squeeze" the diffusing atom from one site to another site.
Light reflected from a medicine cabinet mirror is an example of specular reflection. a) True b) False
a) True
The remanent magnetization of a material is its level of permanent, internal magnetization in no applied magnetic field. a) True b) False
a) True
Could you shape/size a metal, let's say gold, in such a way to get it to have the performance of optical transparency that would be needed for it to serve as a "window"? a) Yes b) No
a) Yes
Does the orientation of the linear polarizer in a sunglass lens matter? a) Yes, the orientation of the polarizer is important in determining the performance of the sunglasses b) No, the polarizer can be in any orientation and provide the same overall performance to the sunglasses
a) Yes, the orientation of the polarizer is important in determining the performance of the sunglasses
In the design of a new aircraft, which materials selection and design decision for the wings is likely the most appropriate? a) a new material with a higher yield strength is chosen so that the wing's thickness can be reduced (light-weighting) without compromising its load capacity b) a new material with a lower yield strength is chosen so that the wing's thickness can be increased (light-weighting) without compromising its load capacity c) a new material with a lower yield strength is chosen so that the wing's thickness can be reduced (light-weighting) without compromising its load capacity d) a new material with a higher yield strength is chosen so that the wing's thickness can be increased (light-weighting) without compromising its load capacity
a) a new material with a higher yield strength is chosen so that the wing's thickness can be reduced (light-weighting) without compromising its load capacity
This refrigerator door is most likely made out of: a) a soft magnetic material b) a magnetized hard magnetic metal with a curie temperature above 100 degrees C c) a paramagnetic material d) a diamagnetic material
a) a soft magnetic material
What is the inverse of electrical conductivity? a) electrical resistivity b) electrical conductance c) electrical susceptibility d) electrical admittance e) electrical resistance
a) electrical resistivity
Which of the following properties is an example of a mechanical property? a) hardness b) pyroelectricity c) refractive index d) emissivity
a) hardness
Thermal barrier coatings on turbine blades... a) have a low thermal conductivity in order to increase the service temperature of the underlying metal component b) have a low thermal conductivity in order to decrease the service temperature of the underlying metal component c) have a high thermal conductivity in order to increase the service temperature of the underlying metal component d) have a low coefficient of thermal expansion to ensure no delamination from the turbine blade e) both A and D f) both C and D
a) have a low thermal conductivity in order to increase the service temperature of the underlying metal component
The materials property that describes the amount of heat energy stored for a given temperature differential is the: a) heat capacity b) thermal conductivity c) CTE mismatch d) heat flux e) thermal diffusivity
a) heat capacity
Ceramics typically have: a) higher hardness than metals b) hardness comparable to a metal c) lower hardnesses than metals
a) higher hardness than metals
A material will thermalize (in other words, reach thermal equilibrium) most quickly when: a) its thermal conductivity is high and its heat capacity is low b) its thermal conductivity is high and its heat capacity is high c) its thermal conductivity is low and its heat capacity is high d) its thermal conductivity is low and its heat capacity is low
a) its thermal conductivity is high and its heat capacity is low Materials quickly thermalize when their thermal diffusivity is high. Thermal diffusivity increases with increasing thermal conductivity and decreasing heat capacity.
Pure elemental metals have _____ yield strengths. a) low b) high
a) low
How would you classify cotton as a material? a) polymer b) elastomer c) composite d) both A and B e) A, B, and C
a) polymer
Which of the following would be considered a chemical property of a material? a) solubility b) ductility c) dielectric constant d) heat capacity
a) solubility
When looking through a linear polarizer at a light source producing randomly polarized light... a) the light intensity will constantly be reduced by 50% as the polarizer is rotated 360°. b) the light intensity will fluctuate between 100% and 50% as the polarizer is rotated 360°. c) the light intensity will fluctuate between 100% and 0% (no light) as the polarizer is rotated 360°. d) the light intensity will be the same as the original light source and remain constant as the polarizer is rotated 360°. e) the light intensity will fluctuate between 50% and 0% (no light) as the polarizer is rotated 360°.
a) the light intensity will constantly be reduced by 50% as the polarizer is rotated 360°.
If a material is deformed elastically, which of the following must be true? a) the strain length of the material varies linearly with the applied stress b) a permanent deformation occurs c) the applied stress will exceed the yield point d) none of the above
a) the strain length of the material varies linearly with the applied stress
What is wrong with the materials selection for the wings in Case 3 (*one of the wings has broken/fractured off*)? a) the toughness is too low b) the elastic modulus is too large c) the yield strength is too low d) the yield strength is too high e) the elastic modulus is too small
a) the toughness is too low
Which of the following approaches would not be useful for improving a plastic's resistance to UV degradation? a) using cathodic protection b) including additives to the plastic's compositional formulation c) adding a coating to the plastic's surface d) selecting a proper material
a) using cathodic protection
Consider a copper rod that is 3.14 meters long, 2 cm in diameter, and has a resistivity of 2x10-6 ohm-cm. If the rod is cut in half what is the resistivity of each piece? a) 1x10-4 ohm-cm b) 2x10-6 ohm-cm c) 1x10-6 ohm-cm d) 2x10-4 ohm-cm
b) 2x10-6 ohm-cm The same as the full piece because there is only a physical change (being cut in half).
The four stress-strain curves shown here are for a metal alloy, a ceramic, a ductile thermoplastic polymer, and an elastomer. Which curve is the metal alloy? a) Curve A b) Curve B c) Curve C d) Curve D
b) Curve B
Electrically conductive materials make good piezoelectrics. a) True b) False
b) False
In steady state, dilute species in a solid usually diffuse from regions of low concentrations to regions of high concentration. a) True b) False
b) False
Materials with high dielectric constants will also be good electrical insulators. a) True b) False
b) False
Tough materials have a high yield strength and a low ductility. a) True b) False
b) False
If you know the composition of a material, then you can fully predict its properties. a) True b) False
b) False The properties of a material depend on much more than composition, including microstructure, internal strains, and crystal structure.
The angle at which light refracts when it enters the flat surface of a material could depend upon: i) the refractive index of a material ii) the wavelength of the light iii) the size of the material iv) the angle of incidence of the light into the material a) Only II. b) I., II., and IV. c) Only I. d) I. and IV. e) I., II., and III.. f) I. and II.
b) I., II., and IV.
Materials A, B, and C have the thermal properties listed below. You are asked to choose the best material for a cooking pot. For this application, you want to optimize the speed to thermalize the material (i.e. rate to reach equilibrium temperature with heat source). Which material(s) would you recommend? Material A: Thermal Conductivity = 10 W/m-K Heat Capacity = 5 J/m^3-K Material B: Thermal Conductivity = 9 W/m-K Heat Capacity = 3 J/m^3-K Material C: Thermal Conductivity = 10 W/m-K Heat Capacity = 4 J/m^3-K a) Material A b) Material B c) Material C d) Material A and B will have equally good performance
b) Material B
The stress-strain curves for three materials are shown below (materials A, B, and C). Amongst these three materials which one has the greatest toughness? a) Material A b) Material B c) Material C d) Materials A and B have the same toughness e) Materials B and C have the same toughness f) Materials A and C have the same toughness
b) Material B
The above images plot the magnetic response for two different materials. The plots show the magnetization (M) of the material as a magnetic field (H) is varied from positive values to negative values. Which of these plots shows a soft magnetic material (*A has a wider curve and B has a thin, tall curve*)? a) Material A is the soft magnet b) Material B is the soft magnet c) this information cannot be determined from the available data
b) Material B is the soft magnet
You are designing a system based on piezoelectric actuation to precisely move objects at the nanometer scale. Your system is limited to an operating voltage of 500 V. The system must be able to move objects at least 150 nm. You are allowed to select amongst the following piezoelectric materials in the table below to accomplish this mechanical motion. Which of these materials would you recommend for this mechanical manipulation system? Material I: d33 = 100 pm/V Material II: d33 = 200 pm/V Material III: d33 = 400 pm/V Material IV: d33 = 1000 pm/V a) None of these materials will work for this application. b) Materials III and IV c) Material IV only d) Material III only e) All of these materials will work (I, II, III, and IV) f) Materials II, III, and IV
b) Materials III and IV
Consider the diffusion of oxygen ions through a solid fuel cell membrane. If youd ouble the absolute operating temperature of the fuel cell, what will happen to the diffusivity of the oxygen ions in the membrane? a) The diffusivity of the oxygen ions in the fuel cell membrane will decrease to about half of its original value. b) The diffusivity of the oxygen ions in the fuel cell membrane will increase by a lot more than double its original value. c) The diffusivity will remain constant because diffusivity is a materials property and the membrane material has not changed. d) The diffusivity of the oxygen ions in the fuel cell membrane will increase by about double its original value.
b) The diffusivity of the oxygen ions in the fuel cell membrane will increase by a lot more than double its original value.
What does the exponential expression in the Arrhenius equation physically represent? a) The rate at which an atom will overcome the activation barrier for some process (e.g., diffusion) at a given temperature. b) The fractional probability that an atom has enough thermal energy to overcome the activation barrier for some process (e.g., diffusion). c) The rate at which an atom will overcome the activation barrier for some process (e.g., diffusion) at a given pressure. d) This exponent is just a scaling factor; it has no physical meaning. e) The fractional probability that an atom has enough momentum to overcome the activation barrier for some process (e.g., diffusion).
b) The fractional probability that an atom has enough thermal energy to overcome the activation barrier for some process (e.g., diffusion).
Will one of these designs be superior to another at preventing corrosion (*Design A has different type of metal on inside of container next to water while Design B has different type of metal on outside of container away from the water*)? a) Yes, Design A will be more corrosion resistant b) Yes, Design B will be more corrosion resistant c) No, both designs will be equally corrosion resistant
b) Yes, Design B will be more corrosion resistant Having the welds on the outside of the tank greatly reduces or even eliminates the contact between the weld material and the water. Impeding the flow of ions in solution from one metal to another will reduce galvanic corrosion.
What is most likely to happen in the two metal system shown above (*iron and zinc touch in salt water environment*)? a) neither metal will corrode b) Zinc will oxidatively corrode, while iron remains metallic c) iron will oxidatively corrode, while zinc remains metallic d) both metals will oxidatively corrode
b) Zinc will oxidatively corrode, while iron remains metallic
Optical dispersion is: a) a performance parameter that describes how much the refractive index of a material varies with the wavelength of incident light. b) a material property that describes how much the refractive index of a material varies with the wavelength of incident light. c) a material property that describes how much the polarization of light varies with the wavelength of incident light. d) a performance parameter that describes how much the polarization of light varies with the wavelength of incident light.
b) a material property that describes how much the refractive index of a material varies with the wavelength of incident light.
If you are designing a diving board (spring board) for a swimming pool, you want the board to flex but neither break nor permanently deform. To get these properties, you would desire: a) a relatively low yield strength and a high fracture toughness b) a relatively low elastic modulus but a high yield strength c) a relatively low elastic modulus and a relatively low yield strength d) a relatively high elastic modulus and a high yield strength
b) a relatively low elastic modulus but a high yield strength
Ceramics have elastic moduli that are: a) comparable to polymers b) comparable to metals c) lower than metals
b) comparable to metals
What is a good verb starting with the letter "D" that describes what engineers do? a) describe b) design c) discern d) discover
b) design
Metals are good: a) electrical insulators b) electrical conductors
b) electrical conductors
You are hired by a bedding company to design a new mattress. Your first project is to design a "firm" mattress (that is, one that does not compress very much when you lay on it). Below are the stress-strain curves that have been collected for three different foams loaded under compression. Amongst these three foams, which would you select to make the "firmest" mattress and why? a) foam A because it has the highest elastic modulus b) foam B because it has the highest elastic modulus c) foam A because it has the highest yield strength d) foam c because it has the lowest elastic modulus e) foam A because it has the lowest yield strength f) foam c because it has the highest yield strength g) foam B because it has the highest yield strength
b) foam B because it has the highest elastic modulus
One form of electrochemical degradation of a material is called: a) photodegradation b) galvanic corrosion c) combustion d) dissolution
b) galvanic corrosion
if you were asked to design a cell phone screen that could not be scratched, which material property would you try to maximize? a) density b) hardness c) ductility d) resilience
b) hardness
Most crystalline ceramics have thermal conductivities that are: a) comparable to metals b) intermediate between metals and polymers c) comparable to polymers
b) intermediate between metals and polymers
Compared to other classes of materials, polymers have: a) higher mechanical stiffness b) lower mechanical stiffness
b) lower mechanical stiffness
Lenses use refraction to focus light to a single point. The focal length is the distance from the lens to this "focal point". Assume you are hired to design a new lens for a microscope. The lens must remain the same size, but the focal length must be reduced. What would you recommend? a) Make the new lens out of a new material with a smaller refractive index. b) make the new lens out of a new material with a larger refractive index. c) Make the new lens out of a new material having greater dispersion. d) Suggest both A & C. e) Suggest both B & C f) Quit your job and find something easier to do.
b) make the new lens out of a new material with a larger refractive index.
When you touch each block, the metal block feels "cold" while the plastic block feels "temperate". In which case are you actually feeling the ambient room temperature? a) the block of plastic b) the block of metal
b) the block of metal
The polarization of light is defined by: a) the polarity of the magnetic field b) the direction of the light wave's electric field vector c) the direction of light propagation d) the direction of the light wave's magnetic field vector
b) the direction of the light wave's electric field vector
In the representative stress-strain plot for a material shown below, the point A represents: a) the ductility of the material b) the yield strength of the material c) the toughness of the material d) the ultimate tensile strength of the material
b) the yield strength of the material
Frosted windows... a) have higher visible light transmission than non-frosted windows b) use surface roughness to scatter light and distort the image you see c) use surface roughness to alter the polarization of light and distort the image you see d) use light absorption to distort the image that you see
b) use surface roughness to scatter light and distort the image you see
A ceramic rod that is 10 cm long has a thermal expansion coefficient of 8 x 10-6 (m m-1 K-1). What percent strain elongation does the rod undergo when it undergoes a temperature increase of 1000 degrees C? (remember to multiply strain by 100% to get percent strain) a) 8% strain b) .08% strain c) .8% strain d) 12.5% strain e) .125% strain
c) .8% strain
You are asked to help design the thermal expansion joints for a bridge, The bridge will have one joint on both sides of the bridge where it connects to the earth. Assume that the earth does not move with temperature fluctuations. The brdige is 100 m long and will be manufactured from a steel with a thermal expansion coefficient of 10nppm/degree C. All manufacturing will be in an indoor facility kept at 25 degrees C. Assume that once installed, the bridge may see temperature fluctuations from -30 degrees C to 45 degrees C. What should be the minimum gap size for the thermal expansion joints? a) .1 cm b) .2 cm c) 1 cm d) 2 cm e) 2.75 cm f) 3.75 cm g) 4 cm h) 5.5 cm i) 7.5 cm j) 11 cm
c) 1 cm
At room temperature, the polymer p-BUZZ has a diffusion coefficient for organic solvent molecules of about 10-7 cm2/s. What is a good estimate for the average length of time it will take a solvent molecule to diffuse through a 10 micron thick membrane of p-BUZZ? a) 100 s b) 1000 s c) 10 s d) 10,000 s e) 1 s
c) 10 s
You are asked to design a solution processing method for manufacturing Nylon-6 components. In this process, the polymer is dissolved in a solvent, cast into the final desired shape, and then the solvent is evaporated. Which solvent would you choose for this process? a) anone b) nylon-6 c) 10% acetic acid solution d) benzene e) both benzene and anone would be good solvents to use f) acetone
c) 10% acetic acid solution The Nylon-6 needs to be able to dissolve in the solvent, so look for the non-resistant section.
The four stress-strain curves shown here are for a metal alloy, a ceramic, a ductile thermoplastic polymer, and an elastomer. Which curve is the thermoplastic polymer? a) Curve A b) Curve B c) Curve C d) Curve D
c) Curve C
You work for an electronics manufacturer and are asked to design a new capacitor. The capacitor has a basic parallel plate design, so the dielectric layer will be a "flat" square. Assuming the capacitor must be a fixed thickness (really thin for the latest smart phone) and you want to have the smallest area possible (smallest overall size), which of the following materials would you recommend? a) Buzz Storage Plus Dielectric Constant: 15 Electrical Resistivity: 150 giga-ohms-meters b) Blue-Gold Charge Separator Dielectric Constant: 25 Electrical Resistivity: 100 giga-ohms-meters c) GT Charge Master Dielectric Constant: 25 Electrical Resistivity: 150 giga-ohms-meters d) The Burdell Special Dielectric Constant: 15 Electrical Resistivity: 100 giga-ohms-meters
c) GT Charge Master Dielectric Constant: 25 Electrical Resistivity: 150 giga-ohms-meters For smallest area, look at the highest dielectric constant and the highest electrical resistivity.
You are asked to help design a bimetallic temperature sensor. You are given five metal alloys to work with; their thermal expansion coefficients are listed below. Assuming the elastic properties for each alloy are identical, which combination of alloys would give you the largest temperature-sensitive deflection for your sensor design? Thermal Expansion Coefficients of Alloys: Alloy 1: 15 m/m-K Alloy 2: 10 m/m-K Alloy 3: 10 m/m-K Alloy 4: 8 m/m-K Alloy 5: 5 m/m-K a) Alloy 2 and 3 b) alloy 1 and 2 / alloy 1 and 3 would give equally large deflections c) alloy 1 and 5 d) alloy 4 and 5 e) alloy 1 and 2 f) alloy 1 and 4
c) alloy 1 and 5 To get the largest deflection, you want to pick the pair of metals with the largest difference in thermal expansion coefficients.
What is a good verb starting with the letter "D" that describes what scientists do? a) discern b) design c) discover d) describe
c) discover
Which of these is not a materials constant? a) index of refraction b) thermal conductivity c) electrical resistance d) dielectric constant e) heat capacity
c) electrical resistance
If you "squeeze on" (compressively strain) a piezoelectric material, it will: a) heat up b) cool down c) generate an electric voltage d) explode
c) generate an electric voltage
Calcite would be able to scratch: a) fluorite b) quartz c) gypsum d) both A and B e) none of these
c) gypsum
A good dielectric material designed for use in a capacitor should: a) have a low dielectric constant and be a good electrical insulator b) have a low dielectric constant and be a good electrical conductor c) have a high dielectric constant and be a good electrical insulator d) have a high dielectric constant and be a good electrical conductor
c) have a high dielectric constant and be a good electrical insulator
Which of the following is not an example of an elastic moduli? a) bulk modulus b) shear modulus c) impression modulus d) Young's modulus
c) impression modulus
Which two classes of materials properties are coupled in the piezoelectric effect? a) electrical and thermal b) electrical and optical c) mechanical and electrical d) mechanical and optical
c) mechanical and electrical
A new paint is designed to only reflect red light and absorb all other colors. What color would you perceive for an object that has been coated with this paint? a) purple b) bluish green c) red d) green
c) red
The image is showing an example of what optical phenomenon (*light is bending at an angle through a transparent material*)? a) diffuse scattering b) Kerr effect c) refraction d) dispersion e) diffraction
c) refraction
How does waxing a car help make it "shine"? a) the wax creates new surface asperities to increase diffuse reflection b) the wax fills in surface asperities to increase diffuse reflection c) the wax fills in surface asperities to increase specular reflection d) the wax creates new surface asperities to increase specular reflection
c) the wax fills in surface asperities to increase specular reflection
What is wrong with the materials selection for the wings in Case 2(*only one wing is bent upwards, but it is permanently upwards now*)? a) the elastic modulus is too small b) the yield strength is too high c) the yield strength is too low d) the toughness is too low e) the elastic modulus is too large
c) the yield strength is too low
The materials property that determines the amount of heat flux that will flow across a given length of material at a fix temperature difference is: a) thermal diffusivity b) heat capacity c) thermal conductivity d) thermal expansion coefficient e) thermal flux capacitance
c) thermal conductivity
What is the maximum number of covalent bonds that a single carbon can form? a) 1 covalent bond b) 2 covalent bonds c) 3 covalent bonds d) 4 covalent bonds e) 6 covalent bonds
d) 4 covalent bonds
Why are the lenses of good sunglasses made from linear polarizers? a) These polarizers make it easier to see images on screens that emit linearly polarized light. b) Actually, linearly polarized lenses do not improve the performance of sunglasses, that is a marketing ploy! c) Because the polarizer will block 50% of the light coming from the sun no matter which way you look at it. d) Because light that reflects off of a surface (glare) has a preferential linear polarization, and these polarized lenses selectively block that portion of the reflected light.
d) Because light that reflects off of a surface (glare) has a preferential linear polarization, and these polarized lenses selectively block that portion of the reflected light.
An example of galvanizing steel is which of the following? a) Electrically connecting the steel to a sacrificial anode. b) Electrochemically oxidizing the steel in a controlled manner. c) Coating the steel with acrylic paint. d) Coating the steel with zinc. e) Including additives in the steel's metallurgical composition prior to solidifying it.
d) Coating the steel with zinc.
What does it mean and what happens when you "cross" two linear polarizers? a) Crossing linear polarizers is when you orient each such that they let through light waves with polarizations that are rotated 90° relative to one another; the result is blocking 50% of all light that is transmitted through the two polarizers (assuming nothing is in between the two polarizers). b) Crossing linear polarizers is when you orient each such that they let through light waves with polarizations that are rotated 180° relative to one another; the result is blocking 50% of all light that is transmitted through the two polarizers (assuming nothing is in between the two polarizers). c) Crossing linear polarizers is when you orient each such that they let through light waves with polarizations that are rotated 180° relative to one another; the result is blocking all light that is transmitted through the two polarizers (assuming nothing is in between the two polarizers). d) Crossing linear polarizers is when you orient each such that they let through light waves with polarizations that are rotated 90° relative to one another; the result is blocking all light that is transmitted through the two polarizers (assuming nothing is in between the two polarizers).
d) Crossing linear polarizers is when you orient each such that they let through light waves with polarizations that are rotated 90° relative to one another; the result is blocking all light that is transmitted through the two polarizers (assuming nothing is in between the two polarizers).
The four stress-strain curves shown here are for a metal alloy, a ceramic, a ductile thermoplastic polymer, and an elastomer. Which curve is the elastomer? a) Curve A b) Curve B c) Curve C d) Curve D
d) Curve D
In the stress-strain curve shown below, which point best represents the strain at fracture? a) A b) B c) C d) D
d) D
Consider two materials (A and B) with mechanical stress-strain curves shown below. Which of the following statements accurately describes the mechanical properties of these two materials? a) Material A and B have the same stiffness, but Material A will yield at a lower stress than Material B b) Material A and B have the same strength, but Material A will flex more at low stresses than Material B c) Material A and B have the same strength and stiffness, but Material B will fail at a lower stress than Material A d) Material A and B have the same stiffness, but Material B will yield at a lower stress than Material A e) Material A and B have the same strength, but Material B will flex more at low stresses than Material A f) Material A and B have the same strength and stiffness, but Material A will fail at a lower stress than Material B
d) Material A and B have the same stiffness, but Material B will yield at a lower stress than Material A
A 316 stainless steel alloy melts at 1380 degrees C. Would you recommend its use for a turbine blade application that will operate at 1350 degrees C. Why? a) Yes, I would recommend its use because stainless steel is resistant to thermal oxidation b) Yes, I would recommend its use because the operation temperature is below melting temperature c) No, I would not recommend its use because the material will be heated over its melting temperature d) No, I would not recommend its use because most materials do not retain their properties this near their melting temperature e) Yes, I would recommend its use because stainless steel has a high elastic modulus
d) No, I would not recommend its use because most materials do not retain their properties this near their melting temperature
Compared to a building with walls of wood, a building with walls of bricks is more energy-efficient in maintaining its internal climate with the temperature swings of the day because in the winter (northern hemisphere)... a) The brick's lower heat capacity allows it to absorb less heat during the hot parts of the daytime and then release that heat for shorter times throughout the cool nights. b) The brick's lower heat capacity allows it to absorb more heat during the hot parts of the daytime and then release that heat for longer throughout the cool nights. c) The brick's higher thermal conductivity allows it to absorb more heat during the hot parts of the daytime and then release that heat for longer throughout the cool nights. d) The brick's higher heat capacity allows it to absorb more heat during the hot parts of the daytime and then release that heat for longer throughout the cool nights. e) The brick's lower thermal conductivity allows it to absorb less heat during the hot parts of the daytime and then release that heat for shorter times throughout the cool nights. f) The brick's lower thermal conductivity allows it to absorb more heat during the hot parts of the daytime and then release that heat for longer throughout the cool nights.
d) The brick's higher heat capacity allows it to absorb more heat during the hot parts of the daytime and then release that heat for longer throughout the cool nights.
This type of amterial magnetizes when a magnetic field is applied and stays magnetized when the magnetic field is removed: a) a soft paramagnetic material b) a hard paramagnetic material c) a soft ferromagnetic material d) a hard ferromagnetic material e) both A and B f) both C and D g) both A and C h) both B and D i) all of them (A, B, C, D)
d) a hard ferromagnetic material
If you want to cathodically protect a copper water line, which sacrificial anode material might you use (*iron and zinc are below copper on standard reduction potentials while silver is above copper on SRP*)? a) iron b) zinc c) silver d) both A and B would work e) none of these would work; you cannot cathodically protect a copper pipe
d) both A and B would work
Which of these is NOT a materials constant? a) refractive index b) thermal conductivity c) electrical resistivity d) capacitance
d) capacitance
Based on the classroom discussion, which of the following best describes what a physicist does? a) designs new materials b) solves problems for chemists c) engineers new components d) discovers new physical principles
d) discovers new physical principles
if you load each of these composites in the lateral direction as shown with the red arrows, which composite will have the highest stiffness? Assume that all materials and interfaces used in each of these composites are the same and the fraction of each materials used is the same (only the geometry and arrangement of the two materials is different). The light brown matrix material is a low stiffness polymer while the gray filler material (particles, rods, laminate sheets) is a high stiffness glass. a) particles in a matrix b) short fiber composite c) continuous fiber reinforcement d) laminate
d) laminate
A 1 cm thick piece of silver stainless steel metal is measured to reflect 95% of visible light. How much light is absorbed by this metal/ a) 100% b) 0% c) It cannot be determined without knowing the amount of light that is transmitted through the metal d) 1% e) 5% f) 95%
e) 5%
You work for a manufacturing facility that produces electrical resistors. Currently, you sell a resistor that has a length of 9 cm, a cross-sectional area of 3 cm^2, and uses Metal A with an electrical resistivity of 2 ohm-cm. Unfortunately, the melting point of the resistive metal is too low and these resistors keep failing due to melting in operation. You are asked to design a new resistor with the same resistance using Metal B which has a higher melting temperature. Metal B has an electrical resistivity of 3 ohm-cm. What would you recommend for its design? a) it is impossible to design a resistor with the same resistance because Metal B has a higher melting temperature than Metal A. b) Length = 1 cm; Cross-sectional Area = 2 cm2 c) It is impossible to design a resistor with the same resistance because Metal B has a higher resistivity than Metal A. d) Length = 3 cm; Cross-sectional Area = 2 cm2 e) Length = 2 cm; Cross-sectional Area = 1 cm2 f) Length = 9 cm; Cross-sectional Area = 2 cm2 g) Length = 2 cm; Cross-sectional Area = 9 cm2
e) Length = 2 cm; Cross-sectional Area = 1 cm2
Anodization of aluminum can be used to do all of the following except: a) protect against corrosion b) change the color of aluminum c) make the surface harder d) both A and C e) anodization can be used to do all three of these (A, B, and C)
e) anodization can be used to do all three of these (A, B, and C)
How would you classify the material aluminum arsenide? a) metal b) ceramic c) semiconductor d) a composite of A and B e) both B and C
e) both B and C
Roughening the surface of a material (by, for example, rubbing the surface with sandpaper) is an example of: a) modifying the material constant of a material in such a way as to have no influence on its performance in a given application b) modifying the shape of a material in such a way as to have no influence on its performance in a given application c) modifying both the shape and material constant of a material d) modifying the material constant of a material that may change its performance for a given application e) modifying the shape of a material in a way that may change its performance for a given application
e) modifying the shape of a material in a way that may change its performance for a given application
The emissivity of a material determines the spectral intensities of light emitted from the material at a temperature above absolute zero. Thus, emissivity is an example of a material constant that crosses which two classes of properties? a) magnetic and electrical b) optical and magnetic c) electrical and thermal d) electrical and optical e) optical and thermal
e) optical and thermal
Most of the materials we use today were developed... a) before 1900 b) during the stone age c) between 1800 and 1900 d) during the bronze age e) since 1900
e) since 1900
You are designing an underwater vessel that can avoid sonar. Sonar is essentially sound waves traveling through water. The goal is to find a material that will transmit sound waves in water, so that sonar will travel right through it without reflecting the signal back, leading to detection. Water has a density of 1 g/cm^3 and an elastic modulus of 2.2 GPa. You design a new polymeric material with a density of 2 g/cm^3 and an elastic modulus of 1 GPa. What is your rationale and prediction for how this polymer would perform in the application described above? a) the acoustic impedance of the water and the polymer are significantly different from one another, so sound will most likely reflect at the water/polymer interface and the material will not perform well in this intended application b) the acoustic impedance of the water and the polymer are significantly different from one another, so sound will likely transmit across the water/polymer interface and the material will perform well in this intended application c) the elastic moduli of the water and the polymer are significantly different from one another, so sound will likely reflect across the water/polymer interface and the material will perform well in this intended application d) the elastic moduli of the water and the polymer are fairly similar to one another, so sound will likely transmit across the water/polymer interface and the material will perform well in this application e) the acoustic impedance of the water and polymer are fairly similar to one another, so sound will likely transmit across the water/polymer interface and the material will perform well in this intended application f) the elastic moduli of the water and the polymer are significantly different from one another, so sound will likely transmit across the water/polymer interface and the material will perform well in this intended application
e) the acoustic impedance of the water and polymer are fairly similar to one another, so sound will likely transmit across the water/polymer interface and the material will perform well in this intended application
What is wrong with the materials selection for the wings in Case 1 (*airplane wings are bent upwards in a semicircle shape*)? a) the toughness is too low b) the yield strength is too high c) the yield strength is too low d) the elastic modulus is too large e) the elastic modulus is too small
e) the elastic modulus is too small
You are asked to help design a chemical purification process using diffusion of the impurities through a polymer membrane. The customer wants to reduce the time it takes to purify the chemical stream. What might you suggest to increase the rate of purification? (Note: "Free volume" is the amount of "open space" in a polymer.) a) Switch to a polymer membrane with less free volume. b) Switch to a polymer membrane with more free volume. c) Raise the temperature of the process. d) Lower the temperature of the process. e) Recommend A and D f) Recommend B and C g) Recommend C only
f) Recommend B and C
You design a rod to hold a chandelier from the ceiling, but then your boss informs you that the chandelier will be twice as heavy. Your initial design will now plastically deform under the weight. Which of the following could be done to your original design to allow it to work with the new chandelier? a) use the same material, but shrink the diameter of the rod b) use the same material, but increase the diameter of the rod c) choose a material with a higher elastic modulus, but keep the rod diameter the same d) choose a material with a higher yield strength but keep the rod diameter the same e) both B and C will work f) both B and D will work g) B, C, and D will all work
f) both B and D will work You can increase the diameter to lower the stress applied from the same load or you can increase the yield strength of the material. Increasing the elastic modulus does not necessarily affect the yield strength, so even if it is a stiffer material, it may still plastically deform at the same stress level.
This series of pictures shows someone evaluating which property of the balls (*person squeezing a ball*)? i) stiffness ii) strength iii) toughness iv) elastic modulus v) work of fracture a) iii only b) both ii and iv c) ii only d) both iii and v e) v only f) both i and iv g) iv only h) i only
f) both i and iv
A metal rod with a square cross-section has a resistance of 8 ohms. If the square edge has a width of 2 cm and the rod has a length of 4 cm, what is the resistivity of the material? a) 32 ohms b) 32 ohm-cm c) 8 ohms d) 4 ohms e) not enough information to calculate f) 4 ohm-cm g) 8 ohm-cm
g) 8 ohm-cm
The modulus of resilience of a material... a) is the critical stress beyond which the material permanently deforms b) can be represented by the area under the elastic portion of the stress-strain curve c) is the proportionality constant in Hooke's law d) describes the amount of reversible mechanical energy storage per unit volume possible in a given material e) both A and B f) both A and C g) both B and C h) both B and D i) B, C, and D j) A, B, C, D
h) both B and D