Technology Flashcards
1
Q
- Technology is
- Materials
- Types of materials commonly used
A
- A set of techniques that humans use to design, build and maintain objects and systems that we want or need
- There are many types of materials. The choice of materials is important in the producing a good quality technical object
- Wood
- Metals and Alloys
- Ceramic
- Plastic
2
Q
- Constraint
- Compression
- Tensions
- Torsion
- Deflection
- Shearing
A
- An external force that is exerted on materials and that has a tendency to deform them.
- Forces that tend to crush it; Crushing a can, squeezing a wet sponge; →<
- Forces that tend to stretch it; Copper being stretched into wire. Tug of war; ⇔
- Forces that tend to twist; Hands wringing a towel. Earthquake twisting a bridge;
- Forces that tend to bend something; Fish bending a fishing rod. Clothes pushing down on a clothesline.
- Forces that tend to cut; scissors cutting a paper
3
Q
- Mechanical Properties
- 6 properties
A
- The mechanical properites of a material describes how it reacts when subjected to one or more constraints (forces)
- Hardness: Ability to resist indentation (nicks) or abrasion (scratches)
- Elasticity: Ability to return to their original shapes after undergoing a constraint.
- Resilience: Ability to resist shocks without breaking
- Ductility: Ability to stretch without breaking
- Malleability: Ability to be flattened or bent without breaking
- Stiffness: Ability to retain their shapes when subjected to various constraint
4
Q
- Other properites of materials
- 6 properties
A
- Resistance to Corrosion: Ability to resist the effects of corrosive substances which cause the formation or rust for example
- Electrical Conductivity: Ability to carry an electric current.
- Thermal Conductivity: Ability to transmit heat
- Problems that include water or outdoor weather
- Circuits
- Tranfer heat we want thermal conductivity, insulate from thermal conductivity
5
Q
- Wood and Modified wood
- Why Wood (4)
- Characteristics of wood (6)
- Degradation:
- Protection
A
- Modified wood is treated wood or material made with wood mixed with other ubstances.
- Easy to work with
- Easy to assemble
- Good thermal insluator (keeps heat)
- Does not conduct electricity (avoid shock)
- Hardness: High level
- Elasticity: Good elasticity
- Resilience: Good when has enough moisture
- Ductility: Very low; doesn’t stretch
- Malleabillity: Heat increases its malleability
- Tensile Strength: Excellent; hardwood has a higher level of strength than softwood
- Degradation: Mold causes rotting, easily damaged by fire and termites
- Protection: Varnish, paint and treatment with coating like alkaline solution that contaisnc copper (turns wood bleuish), turns to high temp=stronger
6
Q
- Metal and Alloys
- Commonly used metals:
- Why metal? (2)
- Degradation
- Protection
A
- Metals: Minerals taken from rocks in the ground
- Alloys: Material obtained from mixing a metal with one or more metallic or non-metallic substance
- Iron (Fe), Magnesium (Mg), Copper (Cu), Zinc (Zn), Aluminum (Al), Nickel (Ni), Chrome (Cr), Tin (Sn)
- It’s ductile and malleable
- A good conductor of heat and electricity
- Degradation: Oxidation causes rust, Can melt at high temperatures, dent or bent
- Protection: Coat it with meal coating such as zinc, chrome or nickel, Exposing to hgih heat depending on metal to make the material harder like steel
7
Q
- Ceramics:
- Propeties of ceramics: (5)
- Degradation
- Protection
A
- Result of heating inorganic matter. Made of clay and cements that have been heated.
- High hardness
- Insulator
- Resistance to corrosion
- Low resiliance
- Low elasticity
- Degradation: Brittle (thermal shock), acids or bases causes degradation
- Protection: Baking (potery), Coating them in enamel (similar to paint), avoid exposing them to acids bases and thermal shock.
8
Q
- Plastics:
- Why plastics? (6)
- Two categoris of plastics:
A
- Manuftures material made of molecules called polymers. Come from petroleum, natural gas, or cellulose.
- Can make them into various colours
- Are durable (don’t break down)
- Don’t rust
- Are lighteight
- Are inexpensive
- Insulator
- Thermoplastics and thermosetting plastics
9
Q
- Thermoplastics
- Properties (5)
A
- Can be softened and shaped over and over again
Can be hardened and cooled and keep their properties. Can be easily melted and reshaped.
- Chemical neutrality (stable)
- Elasticity
- Lightness
- Resilience
- stiffness
10
Q
Thermosetting plastics
- Porperties (5)
A
- Can only be heated and shaped once. Once shaped, they remain hard, even when re-heated or they wi;; melt and CANNOT be reshaped.
- Lightness
- Resilience
- Insulator
- Stiffness
- Chemically neutral
- retain shape and strength when heated, they are used in situations where resistance to heat is important. Cooking pot handles, kitchen counters and e;ectrical fittings are made from thermosetting plastics.
11
Q
- Plastics degradation and protection
A
- Degradation
- Liquid easily penetrates into it
- Break, bend, melt, compress easily,
- UV light makes them soften (sunlight)
Protection
- Water proof coatings
- Adding antioxidants like carbon to prevent oxidation
- Add pigments that absorb UV rays
12
Q
Plastics and Food
Why are people concerned about icrowaving food in plastics?
A
- Plastics contains the following chemicals that can leach into the food, when the food items are microwaves in plastics
- Dioxins: An unwanted biproduct of burning trash, waste, and fuel that is cancer causing. Long term exposure to dioxins in animals can lead to reproductive and developmental problems.
- Dioxins are found in some plastics but not all. There is no dioxins in the plastics we microwive! So these are not really a concern
- Phthalates: used to make plastics softer and more flexible and can caue cancer and developmental days.
- Bisphenol A (BPA): Used to make sturdy, stronger clear plastics but can act as a synthetic estrogen that could disrupt human hormone systems, causing various health effects such as reproductive disorder and heart disease.
13
Q
- Mechanical Engineering
- Typical functions of a component
A
- the design, production and the operation of machines which have moving parts
* The parts of a machine are called components - Linking: to join or connect two or more parts together.
* Guiding: the component causes an object to move in a particular fashion.
14
Q
Links
A
- Holds two or more parts of the same object together
- Direct: two parts held together w/o linking component or Indirect: linkimg components is required to hold two parts together
- Rigid: the linking compenent is not flexible or Flexible: the linking compenent can be deformed when used and can return to its inital position
- Removable: the linked parts can be separated w/o damaging either surfaces of linking components or Permanent (non-removable): linked parts cannot be separated w/o damaging either their surfaces or the linking component
- Complete: Linking component prevents the two parts from moving independently of one another or Partial: the linking components allows the two parts to move independently from one another
15
Q
Questions for indentifying the characteristics of links:
A
- Do the parts require something else to hold them together?
- Yes: Direct
- No: Indirect
- Can the linking components be deformed when used and will it return to its inital position?
- Yes: Flexible
- No: Rigid
Can the object be taken apart without causing damage to the object?
- Yes:Removable
- No:Permanent
- Is movement possible betwee the two parts?
- Yes: Partial
- No: Complete
21
Q
Friction Gears
- Description
- Reversiblity
- Advantages
- Disadvantages
A
- Rotational motion= one wheel to another
- Transmission is done by friction between wheels
- Rotation direction is oppoise in each conecting wheel
- Yes
- inexpensive, easy to assemble, will allow slippage, can be positioned perpendicular or at any angle to each other.
- Wheels must always be together, wheels can slip causing interruption in transmission of motion, must be kept clean (no lubrications)
