Fichas
HW 1
Fichas del conjunto (19)
- 1If a material is deformed plastically, which of the following must be true? -The applied stress remains below the yield point. -The strain length of the material varies linearly with the applied stress. -A permanent deformation occurs. -None of the above. -All of the above.A permanent deformation occurs
- 2If you were asked to design a new rubber band that could stretch farther without breaking, which of these material properties would you try to maximize? -Yield Strength -Density -Hardness -Ductility (Strain at Break) -StiffnessDuctility (strain at break)
- 3If you were asked to design a windshield that would resist being scratched by debris while driving, which material property would you try to maximize? -Hardness -Resilience -Ductility (Strain at Break) -Stiffness -DensityHardness
- 4If a material is plastically deformed, this deformation is reversible by removing the load. -True -FalseFalse
- 5Tough materials CANNOT be brittle. -True -FalseTrue
- 6Which of the following is NOT a mechanical property of a material? -Poisson's Ratio -Dielectric Strength -Hardness -Ductility -All of these are mechanical properties of a material.Dielectric Constant
- 7You are designing props for a "western" movie. In the bar fight scene, one of the actresses must break a beer bottle over the head of an actor. Which of the material property(ies) for the bottle listed below is most important to get the scene correct without hurting the actor? A. The bottle material should have low hardness. B. The bottle material should have low toughness. C. The bottle material should have low yield strength. D. The bottle material should have low stiffness.B. The bottle material should have low toughness.
- 8You have been hired by a national defense agency to help design the sonar system for a new submarine. Your first project is to select a material to be used for a sonar detector which will be installed on an external wall of the submarine. The acoustic impedance of water is about 1.5 MPa-s/m. Which of the materials listed below would you select for the submarine's sonar detection panel and why? Acoustic Impedances: Material A: 0.5 MPa-s/m Material B: 1.8 MPa-s/m Material C: 3.5 MPa-s/m Material D: 4.5 MPa-s/m -Material D because it has the largest acoustic impedance mismatch with water and will transmit the most sound. -Material B because it has the smallest acoustic impedance mismatch with water and will reflect the most sound. -Material B because it has the smallest acoustic impedance mismatch with water and will transmit the most sound. -Material A because it has the largest acoustic impedance mismatch with water and will transmit the most sound. -Material A because it has the lowest acoustic impedance, which will maximize its acoustic transmission. -Material C becausMaterial B because it has the smallest acoustic impedance mismatch with water and will transmit the most sound.
- 9A material with high yield strength and low ductility would be considered "tough". -True -FalseFalse
- 10Which of these lists of material constants are all examples of mechanical/structural properties? -Modulus of Resilience, Refractive Index, Density -Pyroelectric Coefficient, Poisson's Ratio, Refractive Index -Poisson's Ratio, Density, Heat Capacity -Hardness, Modulus of Resilience, Dielectric Constant -Ductility, Heat Capacity, Yield Strength -Dielectric Constant, Hardness, Ductility -Ductility, Poisson's Ratio, Modulus of ResilienceDuctility, Poisson's Ratio, Modulus of Resilience
- 11The elastic modulus of a material... (select all that apply) A. ...is the critical stress beyond which the material permanently deforms. B. ...is the proportionality constant in Hooke's Law. C. ...is the slope of the linear portion of a stress-strain curve. D. ...can be represented by the area under the elastic portion of the stress-strain curve.Both B&C
- 12The stiffness of a material... (select all that apply) A. ...is the critical stress beyond which the material permanently deforms. B. ...is the critical stress at which the stress-strain curve changes from linear to non-linear. C. ...is the proportionality constant in Hooke's Law. D. ...describes the amount of reversible mechanical energy storage per volume possible in a given material.C. ...is the proportionality constant in Hooke's Law.
- 13When an object is intended to be deployed deep into the ocean's depths, which of the following materials constants would you use to help determine the amount of elastic compression it will experience? Shear Modulus Yield Strength Young's Modulus Impression Modulus Bulk Modulus ToughnessBulk Modulus
- 14Material A has a greater yield strength than Material B. Material B is stiffer than Material A. Material A and Material B have about the same elastic modulus. Materials A and Material B have about the same yield strength.Materials A and Material B have about the same yield strength.
- 15—The Modulus of Resilience
- 16—Toughness of Material
- 17—C
- 18—Materials B & C have about the same strain at break.
- 19—Foam B because it has the highest elastic modulus.
