4.1

Question 1

physical properties

Answer 1

observable characteristics of a material

Question 2

mechanical properties

Answer 2

indicate how a material behaves under various loads

Question 3

list physical properties

Answer 3

• mass (amount of matter in a material)
• weight (relies on gravitational forces as well)
• volume
• density
• hardness (resistance material offers to scratching)
• electrical resistivity
• thermal conductivity
• thermal expansion (degree of increase in dimensions when object is heated)

Question 4

list mechanical properties

Answer 4

• tensile strength (ability to withstand pulling forces)
• compressive strength (abilite to withstand being squashed)
• stiffness (resistance of elastic body to bending under force)
• toughness (ab. to resist breaking when receiving sudden shock)
• brittle (breaks into sharp shards)
• plasticity (avility to be formed into new shape permanently)
• elasticity (ab. to bend and return to original shape)
• ductility (ability to be extruded into wire etc)

Question 5

stress

Answer 5

tensile force applied to given area (F/A)

Question 6

strain

Answer 6

response of material due to stress (change in L/original L)

Question 7

youngs modulus

Answer 7

measure of stiffness of an elastic material. used to select materials for design context

Question 8

yield point

Answer 8

B on og graph. material will no longer return to initial shape

Question 9

necking

Answer 9

netween c and d, going tosard breaking

Question 10

point d on youngs modulus

Answer 10

failure point

Question 11

point c on youngs modulus

Answer 11

ultimate tensile strength

Question 12

material selection chart

Answer 12

charts used to identify appropriate materials based on desired properties

Question 13

aesthetic properties

Answer 13

aspects of product that relate to tastem texture, smell, appearance

Question 14

define smart materials

Answer 14

materials designed to react to external stimuli. adapt, change properties if needed

Question 15

list smart materials

Answer 15

• piezoelectricity – give off small electrical discharge when deformed
• shape memory alloys – metals that go back to original shape after exposure to heat or electricity
• photochromicity – reversible change of color when exposed to light
• electro rheostatic – fluids undergo change in viscosity when exposed to electric field
• magneto rheostatic – fluids undergo changes in viscosity when exposed to magnetic field
• thermoeletricity – electricity produced from heat