Full Engineering iGCSE Flashcards
What’s the gear ratio?
Gear ratio = Number of teeth on driven gear / Number of teeth on driver
What’s the velocity ratio?
Velocity Ratio = Diameter of driven pulley / Diameter of the driver pulley
What’s strength?
Ability of a material to withstand force
What’s yield strength?
Amount of stress needed to start permanently deforming the object
What’s ultime tensile strength?
Stress at which the material fails
What’s ductility?
Amount that a material can be deformed
What’s malleability?
Ability of a material to be deformed without rupturing
What’s hardness?
Ability of a material to resists abrasion/penetration.
What’s stiffness?
Resistance to deformation
What’s strain?
Strain = change in length / original length
What’s stress?
Stress = force / cross-sectional area
What’s Young’s modulus?
Young’s modulus (E) = stress / strain
What’s toughness?
What’s brittleness?
- Ability of a material to withstand an impact without breaking
- Opposite to toughness (how easy it shatters)
What’s an alloy?
Mixture of metals
What two types of alloys are there?
- Ferrous: contain iron
- Non-ferrous: don’t contain iron
Examples of ferrous alloys?
- Stainless steel
- Cast iron
- Steel
Examples of non-ferrous alloys?
- Brass
- Bronze
What’s a composite?
Materials made by combining 2+ different types of materials.
Difference between alloy & composite?
Alloy: Joined chemically
Composite: Not joined chemically (stuck together)
Examples of composites?
- Glass-reinforced plastic (fiberglass)
- Plywood
- Medium density fibreboard
Examples of renewable sources?
- Wind
- Tidal
- Biomass
- Solar
Examples of non-renewable sources?
- Fossil fuels
- Nuclear energy
What’s a system block diagram?
Blocks to represent inputs, processes and outputs.
What’s an input in a system block diagram?
Input device
E.g. Light sensor
What’s a process in a system block diagram?
Processes the signal in some way, changing it
E.g Microcontroller
What’s the output in a system block diagram?
Output device, converts electrical signal into real world signal
E.g. Speaker
What’s a schematic drawing?
- Show individual components
- Represent how it works
- Uses circuit symbols
What’re flowcharts?
Used to show the order in which events are carried out
Used to show steps in a process
What’s the terminator symbol?
Used to indicate beginning/end
What’s Input/Output (flowchart)?
Parallelogram
- Used to show inputs or outputs
What’s a process (flowchart)?
Rectangle
-Shows an action being carried out
What’s a decision (flowchart)?
Diamond
- Choice made
- Splits off
What’s the driven gear?
Gear turned by driver gear.
What’s the driver gear?
Gear turned by a motor to drive other gears
What’s the idler gear?
Intermediate gear between gears to change direction
What’s a cam?
Things that rotates and drives follower
What’s the follower?
Follows cam and moves as cam rotates.
What’s a piezo sounder?
Convert electric signals into sound using the piezo-electric effect.
What’re capacitors?
Capacitance unit?
- Stores electrical charge
- Farads
What’s a hydraulic system?
- Use liquids to transmit power
What’s the diffrence between hydraulic and pneumatic?
Pneumatic: Faster, easier to use, produce less force
Hydraulic: Slower, harder to use, produce more force
What’s an engineer’s rule?
Steel ruler
- Useful for quick measurments
What’re callipers?
Measure internal & external size.
What’s a micrometer?
- Measuring device
- Used to measure small size with accuracy
What’re vernier callipers?
Can take accurate measurements with internal/external jaws
What’s engineer’s blue?
Used to highlight marks and make them stand out
What’s mechanical advantage?
M.A: load / effort
What does Young’s modulus measure?
How stiff a material is.
What’s a polymer?
A chain of small molecules (monomers) joined together.
What are the two main types of polymers?
- Thermoplastics
- Thermosettings polymers
What’re thermoplastics?
Polymers that can be reshaped when hot.
- Ductile
What’re thermosetting plastics?
Polymers that cannot be reshaped when hot.
- Harder & Rigid
What’s timber?
Wood from trees.
What’re ceramics?
Material that are oxide, nitride or carbide of a metal:
- Hard
- Low Ductility
- Very Brittle
What are the different types of cutting processes?
- Sawing
- Shearing
- Laser cutting
What’s sawing?
Movement that progressively cuts away material.
- Have teeth that cut into material
What’s shearing?
Applying a force from opposite sides will cut it in the middle.
What’s laser cutting?
Cutting thin sheets of metals by vaporizing the cut line.
What’s a lathe (turning)?
Round workpiece held by lathe that rotates. Then tools can be used to cut, sand or drill symmetrically.
What’s milling?
Milling is when a rotating tool removes metal layers one at a time from a workpiece.
What’s press forming?
Used to make 3D shapes from metal sheets.
Mould panels are pushed into the metal sheet that deform it into one piece.
What’s punching?
A hole is made in a sheet, material pushed out is scrap, sheet is part.
What’s stamping?
A hole is made in a sheet, material pushed out is the part, sheet is scrap.
What’s a rivet?
Component used to hold sheets together.
What’s a pop rivet?
Used to hold sheets together, only need access to one side.
How does a pop rivet work?
Two parts: Pin & Rivet
- Rivet is inserted into hole
- Pin is pulled by rivet gun
- This deforms rivet on other side
- Makes a tight connection and holds sheet together
What’s soldering?
Process in which two (or more) metal parts are joined together by solder.
What’s welding?
Processs in which two metal parts are joined together by being fused.
What’s the difference between welding & soldering?
Welding: High temperature, fused together.
Soldering: Low-temperature, solder forms join.
What’s normalizing?
Carried out on work hardened steel.
Results in metal that’s tough with ductility, but soft.
How does normalizing work?
Heated just above upper critical point, and let to cool from air.
What’s annealing?
Heat treatment that makes a metal softer.
How does annealing work?
Heating a material, and holding it there for a long time.
What’s hardening?
Heat treatment that increased hardness & strength of material.
What’s quenching?
Quickly cooling of a hot metal by immersing it in oil or water.
How does hardening work?
Heated just above lower critical point. Atoms re-arrange. Then quenched to go to solid form.
What’s tempering?
After hardened, it must be tempered to remove some hardness but reduces brittleness.
How does tempering work?
Hardened steel is heated to 230-300ºC slowly, and quenched again.
What’s mechanical advantage?
Ability of a mechanism to move a large load with a small effort force.
How to calculate mechanical advantage?
Mechanical Advantage = Load / Effort
What’re the 4 types of motion?
- Linear motion
- Rotary motion
- Reciprocating motion
- Oscillating motion
What’s a gear train?
Transmit rotary motion & torque. Made up of multiple gears
Gear ratio equations simplified:
Gear ratio = Driven / Driver
What’s a cam and follower?
Turn rotary motion into reciprocating motion.
What’s a pulley?
Reduce effort when lifting loads and transfer power within a system.
What’s the velocity ratio?
Velocity ratio = Driven Pulley Diameter / Driver pulley diameter
What’s current equation?
Current = Voltage / Resistance
What’s Ohm’s law?
V = IR
What’s main electricity?
Electricity supplied from outlets into homes. 230V AC.
What’s a battery?
Convert chemical energy into electrical energy.
What’s a switch?
Allow current to flow or not flow.
What’s a relay?
Electrically operated switches, when current flow it attracts lever, and closes circuit.
What’s a motor?
Convert current to rotary motion.
What’s a solenoid?
Convert electrical energy into mechanical movement.
What’re buzzers and bells?
Used to create sound when current flows through them.
What’re lamps?
Output devices to create light?
E.G. Leds
What’s an analogue signal?
Signals that change continuously and can take any value within a range.
What’s a digital signal?
Pulses of information in binary.
What’re sensor inputs?
Sensors are used as inputs in electronic systems, can be analogue or digital.
Examples of sensors?
- Thermistors
- Light dependent resistors
What’re process devices?
Brain of electronic system. Changes electrical signal from input, this controls output signal.
Examples of process devices?
- Integrated Circuits
- Timers
- Counters
- Comparators
What’re logic gates?
Electronic process that outputs signals depending on input.
Types of logic gates?
- NOT
- AND
- OR
- NAND
- NOR
What’re programmable devices?
Can be used to perform complex operations. Programs perform actions in it.
Examples of programmable devices?
- Microcontrollers
- PICs
What’re interfacing components?
Boost the output signal going from process to output. Needed as output devices require larger current.
Examples of interfacing components?
- Transistors
- Field Effect transistors FETs
What’re output components?
Turn an electrical signal (voltage or current) into a real world signal such as light or movement.
Outputs components examples:
- LEDs
- 7 Segment Displays
- Piezo sounders
What’re discrete components?
Components that aren’t classified as input or output. Passive components are discrete.
What passive components are there?
- Resistors: Reduce current
- Diodes: Allow current to flow in one direction
- Capacitors: Store electrical charge
What’s a pneumatic system?
Use gas to transmit power.
What’s a hydraulic system?
Uses liquids to transmit power.
Pneumatic features?
- Faster
- Can be blown out and filled with new air
- Clean
Hydraulic features?
- High levels of force
- Cheaper
- Needs reservoir
What’s elasticity?
Ability of a material to return to its original shape when the load upon is removed.
Factor of safety equation?
Factor = yield stress / load
Reactive Maintenance
Physically fix it
Proactive Mainetenace
Plan maintenance, to prevent failure
Additive Manufacturing
Method where part is built up by adding material
Rapid Prototyping
Uses additive manufacturing to make complete part or component
Rapid Prototyping Advantages
- Single Operation
- Computer Operated
- Carried out quickly
- More precisely
- More complex parts
Engineering Rapid Prototyping Disadvantages
- Limited range of materials
