Full Engineering iGCSE Flashcards
1
Q
What’s the gear ratio?
A
Gear ratio = Number of teeth on driven gear / Number of teeth on driver
2
Q
What’s the velocity ratio?
A
Velocity Ratio = Diameter of driven pulley / Diameter of the driver pulley
3
Q
What’s strength?
A
Ability of a material to withstand force
4
Q
What’s yield strength?
A
Amount of stress needed to start permanently deforming the object
5
Q
What’s ultime tensile strength?
A
Stress at which the material fails
6
Q
What’s ductility?
A
Amount that a material can be deformed
7
Q
What’s malleability?
A
Ability of a material to be deformed without rupturing
8
Q
What’s hardness?
A
Ability of a material to resists abrasion/penetration.
9
Q
What’s stiffness?
A
Resistance to deformation
10
Q
What’s strain?
A
Strain = change in length / original length
11
Q
What’s stress?
A
Stress = force / cross-sectional area
12
Q
What’s Young’s modulus?
A
Young’s modulus (E) = stress / strain
13
Q
What’s toughness?
What’s brittleness?
A
- Ability of a material to withstand an impact without breaking
- Opposite to toughness (how easy it shatters)
14
Q
What’s an alloy?
A
Mixture of metals
15
Q
What two types of alloys are there?
A
- Ferrous: contain iron
- Non-ferrous: don’t contain iron
16
Q
Examples of ferrous alloys?
A
- Stainless steel
- Cast iron
- Steel
17
Q
Examples of non-ferrous alloys?
A
- Brass
- Bronze
18
Q
What’s a composite?
A
Materials made by combining 2+ different types of materials.
19
Q
Difference between alloy & composite?
A
Alloy: Joined chemically
Composite: Not joined chemically (stuck together)
20
Q
Examples of composites?
A
- Glass-reinforced plastic (fiberglass)
- Plywood
- Medium density fibreboard
21
Q
Examples of renewable sources?
A
- Wind
- Tidal
- Biomass
- Solar
22
Q
Examples of non-renewable sources?
A
- Fossil fuels
- Nuclear energy
23
Q
What’s a system block diagram?
A
Blocks to represent inputs, processes and outputs.
24
Q
What’s an input in a system block diagram?
A
Input device
E.g. Light sensor
25
What's a process in a system block diagram?
Processes the signal in some way, changing it
E.g Microcontroller
26
What's the output in a system block diagram?
Output device, converts electrical signal into real world signal
E.g. Speaker
27
What's a schematic drawing?
- Show individual components
- Represent how it works
- Uses circuit symbols
28
What're flowcharts?
Used to show the order in which events are carried out
Used to show steps in a process
29
What's the terminator symbol?
Used to indicate beginning/end
30
What's Input/Output (flowchart)?
Parallelogram
- Used to show inputs or outputs
31
What's a process (flowchart)?
Rectangle
-Shows an action being carried out
32
What's a decision (flowchart)?
Diamond
- Choice made
- Splits off
33
What's the driven gear?
Gear turned by driver gear.
34
What's the driver gear?
Gear turned by a motor to drive other gears
35
What's the idler gear?
Intermediate gear between gears to change direction
36
What's a cam?
Things that rotates and drives follower
37
What's the follower?
Follows cam and moves as cam rotates.
38
What's a piezo sounder?
Convert electric signals into sound using the piezo-electric effect.
39
What're capacitors?
Capacitance unit?
- Stores electrical charge
- Farads
40
What's a hydraulic system?
- Use liquids to transmit power
41
What's the diffrence between hydraulic and pneumatic?
Pneumatic: Faster, easier to use, produce less force
Hydraulic: Slower, harder to use, produce more force
42
What's an engineer's rule?
Steel ruler
- Useful for quick measurments
43
What're callipers?
Measure internal & external size.
44
What's a micrometer?
- Measuring device
- Used to measure small size with accuracy
45
What're vernier callipers?
Can take accurate measurements with internal/external jaws
46
What's engineer's blue?
Used to highlight marks and make them stand out
47
What's mechanical advantage?
M.A: load / effort
48
What does Young's modulus measure?
How stiff a material is.
49
What's a polymer?
A chain of small molecules (monomers) joined together.
50
What are the two main types of polymers?
- Thermoplastics
- Thermosettings polymers
51
What're thermoplastics?
Polymers that can be reshaped when hot.
- Ductile
52
What're thermosetting plastics?
Polymers that cannot be reshaped when hot.
- Harder & Rigid
53
What's timber?
Wood from trees.
54
What're ceramics?
Material that are oxide, nitride or carbide of a metal:
- Hard
- Low Ductility
- Very Brittle
55
What are the different types of cutting processes?
- Sawing
- Shearing
- Laser cutting
56
What's sawing?
Movement that progressively cuts away material.
- Have teeth that cut into material
57
What's shearing?
Applying a force from opposite sides will cut it in the middle.
58
What's laser cutting?
Cutting thin sheets of metals by vaporizing the cut line.
59
What's a lathe (turning)?
Round workpiece held by lathe that rotates. Then tools can be used to cut, sand or drill symmetrically.
60
What's milling?
Milling is when a rotating tool removes metal layers one at a time from a workpiece.
61
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.
62
What's punching?
A hole is made in a sheet, material pushed out is scrap, sheet is part.
63
What's stamping?
A hole is made in a sheet, material pushed out is the part, sheet is scrap.
64
What's a rivet?
Component used to hold sheets together.
65
What's a pop rivet?
Used to hold sheets together, only need access to one side.
66
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
67
What's soldering?
Process in which two (or more) metal parts are joined together by solder.
68
What's welding?
Processs in which two metal parts are joined together by being fused.
69
What's the difference between welding & soldering?
Welding: High temperature, fused together.
Soldering: Low-temperature, solder forms join.
70
What's normalizing?
Carried out on work hardened steel.
Results in metal that's tough with ductility, but soft.
71
How does normalizing work?
Heated just above upper critical point, and let to cool from air.
72
What's annealing?
Heat treatment that makes a metal softer.
73
How does annealing work?
Heating a material, and holding it there for a long time.
74
What's hardening?
Heat treatment that increased hardness & strength of material.
75
What's quenching?
Quickly cooling of a hot metal by immersing it in oil or water.
76
How does hardening work?
Heated just above lower critical point. Atoms re-arrange. Then quenched to go to solid form.
77
What's tempering?
After hardened, it must be tempered to remove some hardness but reduces brittleness.
78
How does tempering work?
Hardened steel is heated to 230-300ºC slowly, and quenched again.
79
What's mechanical advantage?
Ability of a mechanism to move a large load with a small effort force.
80
How to calculate mechanical advantage?
Mechanical Advantage = Load / Effort
81
What're the 4 types of motion?
- Linear motion
- Rotary motion
- Reciprocating motion
- Oscillating motion
82
What's a gear train?
Transmit rotary motion & torque. Made up of multiple gears
83
Gear ratio equations simplified:
Gear ratio = Driven / Driver
84
What's a cam and follower?
Turn rotary motion into reciprocating motion.
85
What's a pulley?
Reduce effort when lifting loads and transfer power within a system.
86
What's the velocity ratio?
Velocity ratio = Driven Pulley Diameter / Driver pulley diameter
87
What's current equation?
Current = Voltage / Resistance
88
What's Ohm's law?
V = IR
89
What's main electricity?
Electricity supplied from outlets into homes. 230V AC.
90
What's a battery?
Convert chemical energy into electrical energy.
91
What's a switch?
Allow current to flow or not flow.
92
What's a relay?
Electrically operated switches, when current flow it attracts lever, and closes circuit.
93
What's a motor?
Convert current to rotary motion.
94
What's a solenoid?
Convert electrical energy into mechanical movement.
95
What're buzzers and bells?
Used to create sound when current flows through them.
96
What're lamps?
Output devices to create light?
E.G. Leds
97
What's an analogue signal?
Signals that change continuously and can take any value within a range.
98
What's a digital signal?
Pulses of information in binary.
99
What're sensor inputs?
Sensors are used as inputs in electronic systems, can be analogue or digital.
100
Examples of sensors?
- Thermistors
- Light dependent resistors
101
What're process devices?
Brain of electronic system. Changes electrical signal from input, this controls output signal.
102
Examples of process devices?
- Integrated Circuits
- Timers
- Counters
- Comparators
103
What're logic gates?
Electronic process that outputs signals depending on input.
104
Types of logic gates?
- NOT
- AND
- OR
- NAND
- NOR
105
What're programmable devices?
Can be used to perform complex operations. Programs perform actions in it.
106
Examples of programmable devices?
- Microcontrollers
- PICs
107
What're interfacing components?
Boost the output signal going from process to output. Needed as output devices require larger current.
108
Examples of interfacing components?
- Transistors
- Field Effect transistors FETs
109
What're output components?
Turn an electrical signal (voltage or current) into a real world signal such as light or movement.
110
Outputs components examples:
- LEDs
- 7 Segment Displays
- Piezo sounders
111
What're discrete components?
Components that aren't classified as input or output. Passive components are discrete.
112
What passive components are there?
- Resistors: Reduce current
- Diodes: Allow current to flow in one direction
- Capacitors: Store electrical charge
113
What's a pneumatic system?
Use gas to transmit power.
114
What's a hydraulic system?
Uses liquids to transmit power.
115
Pneumatic features?
- Faster
- Can be blown out and filled with new air
- Clean
116
Hydraulic features?
- High levels of force
- Cheaper
- Needs reservoir
117
What's elasticity?
Ability of a material to return to its original shape when the load upon is removed.
118
Factor of safety equation?
Factor = yield stress / load
119
Reactive Maintenance
Physically fix it
120
Proactive Mainetenace
Plan maintenance, to prevent failure
121
Additive Manufacturing
Method where part is built up by adding material
122
Rapid Prototyping
Uses additive manufacturing to make complete part or component
123
Rapid Prototyping Advantages
- Single Operation
- Computer Operated
- Carried out quickly
- More precisely
- More complex parts
124
Engineering Rapid Prototyping Disadvantages
- Limited range of materials
