Structures

Question 1

what do all structures have in common

Answer 1

they all support or carry a load / the load that they were designed for

Question 2

meaning - structure, contain, protect, support, span, natural structure, man-made structure

Answer 2

structure - something that has been built, put together or made in a particular way to support a load
contain - to enclose / hold something within
protect - to keep something safe / to prevent something from being damaged
support - to be able to carry the weight of something
span - the distance from one end of something to the other, extend across a distance
natural structure - a structure made by nature not man
man-made structure - a structure made by people

Question 3

what are the purposes of structures

Answer 3

most structures have several functions including:

• containing objects
• protecting or sheltering objects
• supporting loads
• spanning distances

Question 4

what 2 groups can structures be classified into

Answer 4

• made-made

- natural

Question 5

give some examples of man-made and natural structures

Answer 5

man - buildings, pylons, bridges

nature - bird feathers, human skeleton

Question 6

what must a structure do to be truly effective

Answer 6

• carry it’s load without toppling / collapsing

- support the parts that make up structure

Question 7

meaning - shell, solid, frame structures, rigid and member

Answer 7

shell structure - hollow structure, contains / protects something by supporting from outside, outside layer hold whole thing together
solid structure - structure is not hollow, usually made from 1 material (can be piling / forming similar materials in particular shape / design) , has no joints, usually strong and usually can support heavy loads
frame structure - framework of rigid parts joined, supports the outside load from inside
rigid - quality of being stiff, firm and difficult to bend
member - name given to 1 of the parts that are joined together in frame structure

Question 8

give examples of the structures

Answer 8

shell - coffee mug, suitcase, honeycomb, eggshell, nutshell
frame - bridge (spans a gap), bicycle
solid - sandcastles, mountains, boulders, bricks

Question 9

meaning - tie beam, tension and compression force and strut

Answer 9

tie beam - horizontal beam / crosspiece that supports other members by holding / pulling other sections together
tension force - force that stretches a member
compression force - force that squashes a member
strut -diagonal rod / bar in frame structure, braces / supports other sections and keeps them in position by pushing against them

Question 10

why do different frame structures share some features

Answer 10

these similarities make the structures stronger and enable different sections to resist forces acting on them

Question 11

what is a very strong shape for frame structures

Answer 11

triangle, it is used in many frame structures and buildings

Question 12

meaning - triangulation, pylons and mine headgear

Answer 12

triangulation - arranging members in frame structure to triangular to make structure stronger
pylons - tall frame structure made from strong materials to help held heavy objects
mine headgear - tall frame structure build above mineshaft to hold machines that transport people and equipment into mines

Question 13

what does triangulation do

Answer 13

it makes frame structures more rigid

Question 14

name 3 structures triangulation is used on to strengthen them

Answer 14

• pylons
• windmills
• mine headgear

Question 15

what is a windmill

Answer 15

tall frame structures, convert wind energy to usable energy, winds turns blades that operate a machine that can grind wheat, pump underground water or generate electricity

Question 16

evaluate a land line

Answer 16

telephones that send signals trough cables underground or suspended in air

Question 17

what are the advantages and disadvantages of landlines

Answer 17

Advantages:

• Reliable - rely on wires, more reliable than mobile phone
• Emergencies - don’t have to worry about signal in emergencies
• Price - calls cheaper than mobile phones

Disadvantages:

• Cable theft - when cables are stolen / broken, no service
• Mobility - they require physical, fixed connection, so can only be used were they are. reception depends on length of attached cord to handset or range cordless phone can receive signal
• Availability - some areas in SA don’t have infrastructure for landlines
• Long-distance charges - calls are charged depending on distance and duration of call

Question 18

evaluate a mobile phone

Answer 18

connects to cellular network, transmit signals using radio waves

Question 19

What are the advantages and disadvantages of mobile phones

Answer 19

Advantages:

• Ease of communication - anyone, anywhere not close to any landlines, and has cell phone and reception can be called
• No long-distance charges - charged by minute, regardless where (except international calling)
• Safety - can call for help whenever you need to

Disadvantages:

• Interruption - can be disruptive, can be called anywhere and time
• Safety - talking on phone can distract you from other activities
• Service - bad weather / software glitches can cause fuzzy reception / calls in progress disconnect
• Availability - some areas in SA don’t provide cell phone coverage