Studied by 2 people
How does fracking work?
A well is drilled into crust until it hits shale rock, sending a high-pressure mixture of water, sand and chemicals to release the gas.
How is a fossil fuel used to generate electricity?
As the fossil fuel burns it generates heat, which is used to create steam that drives a turbine to generate electricity.
What is potential energy?
Stored energy to be released
What is kinetic energy?
• The energy an object has due to its motion • Can be transferred
How are flywheels used in the National Grid?
• When there's low demand, surplus energy spins a flywheel • Flywheels maintain momentum due to an almost frictionless environment • If demand rises the momentum is used to drive a generator to feed energy back into the grid
How do pneumatic systems work?
Pneumatic systems rely on a constant supply of compressed air, provided by an air compressor, to produce a force
How do hydraulic systems work?
Hydraulic systems rely on compressed fluid, provided by a pump, to produce a force
How do batteries work?
They store chemical energy and chemical reactions are used to generate electricity
Give a suitable material for surgical sutures or drug delivery
Biodegradable polymers, break down after use
Give a suitable material to use for receptions desks or door fronts and why
flexible MDF, can be folded into curved desks etc.
Suggest what can be used for joint replacement or fibre optics and why
titanium, strong and light
Suggest what can be used for screens on handheld devices and why
LCDs, compact, light and have low power use
Suggest a suitable material for a frying pan base or antifraud banknotes and why
Teflon, creates a non-stick surface and water-proof
Suggest a suitable material for prototypes and why
polymorph, easy to remould
Why are biodegradable polymers carbon neutral?
Energy used in manufacturing and transport comes from vegetable starch that absorb CO2 during growth, which offsets the CO2 released
Suggest a suitable material for car helmets and why
• Glass-reinforced plastic • Light and strong • Corrosion, chemical and heat resistant
Suggest a suitable material for race cars and why
• Carbon fibre • Light and strong • Good tensile strength • Water and chemical proof
Suggest a suitable material for summer clothing and why
• Gore-Tex • Waterproof • Breathable as moisture vapour can escape
Suggest a suitable material for armour and why
• Kevlar • Very strong and hard-wearing • Cut and tear resistant • High thermal protection
Suggest a suitable material for fire blankets and why
• Fire-resistant fabrics • Resist heat and ignition from naked flame
Suggest a suitable material for medical textiles and why
• Microfibres • Absorbent and fast-drying
Describe the process of making glass-reinforced plastic
Prepare mold
Apply release agent
Apply gel coat
Apply GRP matting
Apply resin and work it evenly into the matting
Clamp in position and leave to cure
Release mold
Trim and finish workpiece
What does analogue mean?
continuous variation with no set scale
What does digital mean?
signals that are on or off with a set scale
Name a smart material affected by sound
piezoelectric material
Name a smart material affect by UV rays
Photochromic pigments
Name smart materials affected by pressure
QTC and piezoelectric material
Name smart materials affected by electricity
QTC, piezoelectric material and shape memory alloy
Name smart materials affected by heat
Thermochromic pigments and shape memory alloy
Name a smart material affected by pH
litmus paper
Name smart materials affected by stress
Piezoelectric material, self-healing polymers
Give an example of a shape memory alloy
Nitinol - alloy of nickel and titanium
Give an example of a piezoelectric material
quartz
How does self healing concrete work?
• When cracks appear water seeps into them rupturing spheres of food and bacteria and activating them • Bacteria begins to feed resulting in calcium carbonate that bonds the concrete and fills the crack
How does QTC work?
• QTC changes its electrical resistance based on changes in applied force. • The more force applied the lower the resistance
How do piezoelectric materials work?
They change shape if voltage is applied
What does a speaker do?
emit sound - output
What does a LDR do?
resistance decreases when light intensity increases - input
What does a LED do?
emits light when a current passes through it - output
What does a push-to-make switch do?
provides a momentary connection - input
What does a push-to-brake switch do?
provide a temporary disconnection - input
What does a buzzer do?
produces an audio signal - output
What does a thermistor do?
resistance decreases when temperature increases - input
What does a toggle switch do?
latches on a connection - input
What is an open loop system?
A system that does not respond to changing conditions
What is a closed loop system?
Uses feedback built into the device to respond to changing conditions
What is a monostable device?
A signal pulse is triggered by a switch or sensor - used for timing length of an event
What is an astable device?
Produces a stream of pulses that are oscillating and constant
What is a linkage?
changes magnitude/direction of a force
What is a class 1 lever?
axis of rotation (fulcrum) is between the effort (force) and load
What is a class 2 lever?
load is between the axis of rotation (fulcrum) and the effort (force)
What does oscillating mean?
repeated back and forth movement of an object
What does reciprocating mean?
repetitive linear motion
What is an idler gear?
A gear that allows the driver gear and the driven gear to turn in the same direction
What is an eccentric cam?
round with hole for offcentred camshaft
What is a snail cam?
long dwell, slow rise, sudden drop
What is a pear cam?
long dwell, rapid rise and fall
What is a constant velocity cam?
designed to have no dwell period
How are pulleys adapted?
• Pulley wheels have V-shaped grooves for extra friction from larger surface area, as well as to insure the belt is engaged • Belts may have notches for more efficient flexing • Pulleys attach to driver shafts to transfer motion to other parts of the mechanism
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