Unit 4 (Final Production) Flashcards
Distinguish between mass and weight (2)
Mass- constant regardless of gravity, measured in kg
Weight- resultant force of gravity on mass, measured in newtons (N)
Distinguish between hardness, stiffness and toughness (3)
Hardness- resistance to scratching or penetration
Stiffness- resistance to bending
Toughness- ability to deform without cracking, or resist fracturing on impact
Distinguish between elasticity and plasticity (2)
Elasticity- ability of a material to be deformed, and then return to its original position
Plasticity- ability of a material to be formed into a new shape
Describe Young’s modulus, and explain the difference between stress and strain
Young’s modulus- a graph depicting the changes in strain with applied stress
Stress- tensile force applied to an area
Strain- percentage of change in the length when the force is applied
What is the quality that allows certain smart materials to change colour when exposed to light?
Photochromacity
What is the quality that allows certain smart materials to release an electric charge when deformed?
Piezoelectricity
What is the quality that allows certain smart materials to change their viscosity when a magnetic field is applied?
What about when an electrical force is applied?
Magneto-rheostatic
Electro-rheostatic
What is the quality that allows certain smart materials to generate electricity when heat is applied?
Thermoelectricity
How does the rate of cooling affect grain size in metals? What are the advantages of larger grains? (1 + 4)
Slower cooling –> larger grains –>
increased tensile strength
increased toughness
increased ductility
increased malleability
Define work hardening and tempering (1 + 1)
Work hardening- the process of increasing the hardness of a metal by applying forces while the metal is cold
Tempering- the application of heat after work hardening (reduces hardness and stiffness, but increases toughness and ductility)
Distinguish the qualities of a superalloy (2)
Superalloys are alloys that exhibit high mechanical strength, resistance to creep (expansion/ deformation) and resistance to oxidation (eg. rust)
How can metals be categorised? (3)
Ferrous (eg. steel, iron)
Non-ferrous (eg. aluminum, copper)
Alloy (eg. brass, tin)
Give the general qualities of softwoods, with examples (4 + 3)
low density (lower hardness)
high flexibility (lower mechanical strength)
generally lighter coloured
fast growing, considered renewable
eg. Douglas fir, sugar pine, redwood
Give the general qualities of hardwoods, with examples (4 + 3)
higher density (higher hardness)
low flexibility (higher mechanical strength)
smooth, range of colours
slow growing, not considered renewable
eg. white oak, American sycamore, black cherry
List examples of engineered woods and their advantages (3 + 3)
Plywood (strong in compression)
MDF (strong, smooth finish)
Fibreboard (cheap, lightweight)
Distinguish between seasoning, treating and finishing timber (3)
Seasoning- removing moisture through long term drying processes
Treating- chemical applications to improve specific qualities, eg. protection from insects/ rot, weathering resistance, etc.
Finishing- improving the aesthetic qualities through the application of a finish, eg stains, oils, waxes
List types of glass and their advantageous properties (4)
Borosilicate (high thermal resistance)
Tempered (high shock resistance)
Fibreglass (flexibility)
Laminated (anti-shatter)
List the general qualities of glass (6)
colour variation
transparency
high compressive strength
low tensile strength
high hardness
Nonporous, non-toxic, unreactive
Distinguish between thermoplastics and thermosets (2)
thermoplastics can be heated and reformed
thermosets cannot be reheated or reformed
Give the general qualities of thermoplastics, with examples (4 + 3)
low production cost
easy to injection mold
low stiffness/ high flexibility
can be reshaped after heating
eg. polypropylene, polyethylene, high impact polystyrene
Give the general qualities of thermosets, with examples (4 + 3)
higher production cost
heat resistant
high stiffness/ low flexibility
cannot be reshaped after heating
eg. urea-formaldehyde, polyurethane, melamine
Distinguish between fibres, yarns, threads and fabric (4)
fibres- raw form
yarn- long continuous fibre
thread- thin yarn used in sewing
fabric- cloth produced by weaving, knitting, felting etc.
Compare the properties of natural and synthetic fibres (4 +4)
NATURAL
high absorbency
low tensile strength
low elasticity
will burn at high temp.
SYNTHETIC
low absorbency
high tensile strength
high elasticity
will burn and melt at high temp.
Give examples of natural fibres, and an advantage of each (3 + 3)
wool (insulative, even when wet)
cotton (most prevalent, low cost)
silk (highest strength of natural fibres)
Give examples of synthetic fibres, and an advantage of each (3 + 3)
nylon (abrasion resistant)
polyester (high strength)
lycra (very high elasticity)
