Section 2 Flashcards
Shale gas
natural gas trapped with in the earths crust rich in petroleum and natural gas
has to be extracted by controversial process fracking(drill hole, shoot chemical mixture to release gas)
it is harmful for the environment as it releases chemicsl and toxic particles into water table
nuclear power good and bad
produces very little co2 emissions
it is considered non finite by some as there is a very high uranium supply
it creates nuclear waste which has to be disposed of and can cause accidents
wind turbine good and bad
relatively cheap and clean
do not work with too much/low wind
they can harm wildlife and birds
people are against them as they destroy natural views
solar energy good and bad
N : only produce energy in they day time
produce less in the winter months
need to be cleaned and require space
tidal energy
movement of water generates electricity by spinning a turbine
G : it is more predictable and consistent than solar or wind
it has to be placed offshore in hard locations, making installation and maintenance expensive
HEP
hydroelectric power - large areas of land are flooded into reservoirs
N: high set up costs financially and environmentally. need to flood and destroy wildlife
G: reservoirs can become leisure sites and promote new wildlife and become nature reserves
water flow through turbine is easily controlled to meet power demand
biofuel
oil and starch producing crops are used to make fuels like biodiesel
G : stops food waste from being wasted and is carbon neutral
N: crops require high amounts of water, land and contribute to food shortages when used for fuel not feeding
pneumatics and hydraulics
transfer mechanical energy through compression of fluids
compression is delivered through a pimp called a compressor which creates pressure
pressure is measured in bar
flywheel
provides continuous energy when energy source is continuous
it evens out erratic energy supplies by storing it when demand is low
it acts as a generator and also motor(aka makes and stores energy as momentum then back to electrical)
it is put in a vacuum and on good bearing to make for frictionless environment
Batteries, how they have improved, types of batteries
1 or more cells together make a battery each cell is 1.5volts
batteries have become smaller in a process called miniaturisation and also more powerful
acid base- traditional type
alkaline cells - use dense paste materials so can be smaller
rechargeable- used for many modern technologies and reduce production costs
disposal of batteries
batteries must be disposed of correctly or otherwise if they enter a landfill they can contaminate soil and wildlife
they are shredded and recovered to be remade
corn starch polymers examples and G B
plastics made from cornstarch rather than petrochemicals
PLA - polyactic acid
PHB - polyhydroxybutate
G: biodégradable, so no effect on the environemtn and not derived from fossil fuel hydrocarbons so no co2 emissions
B: easily décompose so cannot be mixed with other thermoplastics in recycling or entire batch is invalid
Flexible MDF
(Medium Density
Fibreboard)
Made from wood pulp fibre with grooves cut which make it flexible for modern furniture which is curved
Titanium properties and uses
high strength to weight ratio, used in medical professions alot as it is unreactive and in spacecraft alloyed to have higher strength
Fibre Optics
wires that use lights emission to transfer data, infinite, faster but more expensive
Graphene
A single graphite layers which exhibits extremely higher strength compared to its thinness. To be used in electronic and biomedicine
LCD (liquid crystal display)
monochrome and full colour screens which use crystals with a voltage applied to them. Have to be backlit.
nanoparticles uses
nano-medicine computer circuits antibacterials cosmetics
Metal Foam
Lightweight and porous, but still retain properties of metals
Polymorph
biodegradable polymer which can be moulded at
62C and is useful for prototypes as it can be reheated and moulded
smart materials two example
materials that react to external stimuli which changes it properties
fhermocrhomic and photo chromic
can eventually lose ability to return to pre stimulus state
more examples of smart material
Nitinol- nickel titanium alloy used to make stent. Heat to 540 degree to program memory and then heat again to 70 to turn to programmed state
self healing materials - materials with micro encapsulated resin and bio concrete respond to fractures by seeping in and fixing them used for buildings
QTC(quantum tunnelling composite) - polymer that responds to pressure by becoming more conductive used for wearable technology
piezoelectric materials - a voltage is induced across material when stress is applied or vice versa. used for gas lighters
litmus paper - changes colour when in different pH levels, used for scientific testing
composite materials
two or more materials are joined together to create a material with desired characteristics from both
example of fibre resins
GRP - glass fibre matting covered with gel coat for high strength to weight
carbon fibre - cloth woven with this carbon crystalline filaments
high strength to weight ratio of fibre combines with hardwearing property of resin
technical textiles
textiles designed to withstand specific uses with specialised characteristics , where the functions is valued much over aesthetic and cost reduction so they are expensive
two technical textiles example
gore tex - clothing membrane made with many holes. vapour can go through but droplets pass over cuz they too big
Kevlar - made from aramids(modified nylon fibres) with high strength and hardwearing used for bullet proof vests and safety clothing
conductive fabric
fabrics with conductive properties and low resistance used for wearable sports equipment
fire resistant
kevlar and nomex have flame resistant properties
flame retardants are applied to fabrics that slows down ignition and stops it
microfibres and micro encapsulation
a group of synthetic fibres that are less than one denier think
micro encapsulation traps substance with in the material and can slowly release them when rubbed or heated
used for heat regulating and insect repelling
systems
a set of parts and components together that control a task or activity
systems diagrams and open/closed loop systems
systems diagrams are simple flowcharts that show the input processes and outputs of a process
open loop - output is directly controlled by input and has no influence on next input e.g switch is turned on means heater is turned on
closed loop - is able to make decisions using feedback to control the outptut e.g automatic heater sensor
4 types of switches
spst - single pole single throw
spdt - single pole double throw
PTM and PTB - push to make and push to break
polarity in components
having a negative and positive terminal. meaning it matter which way around some components are placed in the switch
transducer drivera
devices that increases the power available to stop a circuit form overheating while trying to get the output to emit
integrated circuit ICs abd microcontroller
a semiconductor wafer with electrical components on it that performs tasks
a modern IC that can perform multiple tasks
analogue vs digital signal
analogue - a continuous ‘wave’ of data that can be any in a range of values
digital data - falls into distinct groups e.g on/off or 0/1 on a switch
PICs
peripheral interface controller - microcontroller which are programmed by sending code from a computer to the IC with a download cable
monostable device
device that is turned on and off for a set period of time and is only stable in the off position
used in
Astable device
oscillating output, with an even difference between each on and off output which can be adjusted
counters
used to keep tallies, display info to a 7 segment display and keep track of processes in a sequence
4 types of motion
linear - in one direction straight
oscillating - back and forth in a pendulum like path
reciprocating - repetitive back and forth
rotary - circular motion around a fixed axis usually
lever
equilibrium
force multipliers used to gain mechanical advantage
MA = L / E
when loads and effortt are balanced around fulcrum
types of lever
first order lever - effort one side , fulcrum in-between , load other side
second order lever - load in between fulcrum and effort
3rd order lever - effort in between fulcrum and load
linkage
a mechanism made by connecting rigid parts to transform direction and magnitude of force
5 types of motion linkage
reverse motion - z shape that changes direction of input to opposite
parallel motion - n shape that keeps direction same
bell crank - quarter circle shape that transfer motion 90 degrees
crank and slider - like a piston, changes rotary motion into reciprocating motion
trade - uses crank changing rotary motion into oscillating motion
rotary systems and main parts
systems used to drive mechanisms in machinery
consister of a cam shaft on which a cam is attached which are both turned by a crank to manipulate a follower
4 types of cam shapes
circular - steady rise and fall
pear- rapid rise and fall with long dwell period
snail- steady rise sudden dropped and long dwell
heart shape- slight rise and fall with no dwell
different types of follower
flat - doesn’t track too accurately and high friction due to larger surface area in contact with cam but copes well under load
knife - tracks accurately but prone to wear and not efficient under load
roller follower - greatly reduced friction
gear trains and idler gear
gears are connected to transfer from drive gear to driven gear.
ratio of teeth of these respectively is the gear ratio
idler gear make the direction of driven and drive gear the same
pulleys and belts , what force is needed
motor is connected to a grooved rimmed wheel called a pulley with a drive belt to transfer rotary motion. friction is needed for them to work and transfer motion so rubber and steel is used
block and tackle
a system of two or more pulleys that can be used to reduce effort
