Definitions Flashcards
1
Q
Element
A
-One type of atom
-Cannot be broken down to simpler form by physical or chemical means
-Exists as single atoms or molecules of one atom (Nitrogen)
2
Q
Valence orbit/electrons
A
-Outermost shell/electrons in outermost shell
3
Q
Isotope
A
-Variation of an atom that has a different number of neutrons
-Has same number of protons as original
-Has different atomic mass but same atomic number as original
-eg Carbon-12 And Carbon-14 are carbon isotopes
4
Q
Atomic Number
A
-Number of Protons in an atom
5
Q
Atomic mass
A
-combined number of protons and neutrons in an atom
6
Q
Covalent Bond
A
-2 non-metals bonded by sharing electrons
-eg water molecules
7
Q
Ionic Bond
A
-Bond formed when an atom transfers one or more electrons to another atom
-Atom that loses electrons becomes a POSITIVE ION
-Atom that gains electrons becomes a NEGATIVE ION
-eg Salt (NaCl)
8
Q
Chemical Compound
A
-pure substance of 2 or more different elements joined via CHEMICAL REACTION
-can only be separated by CHEMICAL MEANS
-has DIFFERENT PROPERTIES to its component elements
9
Q
Mixture
A
-combination of at least 2 different substances
-NOT chemically bonded
-can be separated by PHYSICAL means
-Each component substance MAINTAINS its original properties
10
Q
3 categories of Mixture
A
- Solutions (sea water)
- Suspensions (sand in water)
- Colloids (Clouds, milk etc.)
11
Q
Density
A
-Measurement of mass per unit volume (kg/m^3)
-effects how ‘light’ or ‘heavy’ a material is
12
Q
Properties of solids
A
-Greatest Force of particle attraction
-particles vibrate about fixed positions
-definite shape and volume
-fixed surface
-high density
-difficult to compress
-expands a little when heated
13
Q
Properties of liquids
A
-weak force of particle attraction
-random particle arrangement
-particles move freely but remain close
-takes shape of container
-has definite volume
-has a surface
-high density
-cannot be easily compressed
-expands on Heating (more than solid)
14
Q
Properties of Gas
A
-weak particle attraction
-random particle arrangement
-free and far particle movement
-no definite shape or volume
-no surface
-very low density
-easily compressed
-expands greatly on heating
15
Q
Endothermic
A
-Reaction that takes in energy from surrounding environment
16
Q
Exothermic
A
-Reaction that releases heat into surrounding environment
17
Q
Sublimation
A
-Solid to gas change of state
-skips melting
-doesn’t occur at atmospheric pressure for MOST substances
18
Q
Deposition
A
-Gas to Solid change of state
-Skips condensation
19
Q
Newton’s First Law
A
A body will remain at rest or continue to move with a uniform Velocity unless acted on by a FORCE
20
Q
Vector Quantity
A
-Quantity that has both MAGNITUDE and DIRECTION
-eg Force
21
Q
Moment (Nm)
A
-Static application of Force
-eg bending a beam
22
Q
Torque(Nm)
A
-Dynamic application of Force
-eg rotating a shaft
23
Q
Fulcrum
A
-Centre point about which a force acts
-point from which PERPENDICULAR DISTANCE is measured to calculate moments or torque
24
Q
Principle of Moments
A
-Two opposing moments must have EQUAL MAGNITUDE in order to balance
-eg balancing a see-saw
25
Couples
-Pair of Forces of EQUAL MAGNITUDE and OPPOSITE DIRECTION
26
Resultant
-Effect of 2 or more VECTORS of the same quantity type (eg two Forces)
-Each vector is a COMPONENT of the resultant
-Resultant = Net result of Components added together/difference between them
27
Pythagoras to calculate resultant
-Resultant = Hypotenuse
-Other 2 sides = Components (Vector quantities)
28
Scalar Quantity
-Quantity with MAGNITUDE but no direction
-Can always be expressed NUMERICALLY
29
Centre of Gravity
-Imaginary point through which weight of object is said to act
-Average location of total weight of aircraft (BALANCE POINT)
-Aircraft CoG given as DISTANCE FROM DATUM
30
Stress
-Describes MAGNITUDE of Force causing DEFORMATION (STRAIN)
31
5 Basic structural stresses on aircraft
1.Tension
2.Compression
3.Shear
4.Bending
5.Torsion
32
Strain
-DEFORMATION of material caused by STRESS
-Presented as RATIO
33
Tension
-Stress that increases Length of material
-As TENSION increases, DEFORMATION increases
34
Hooke’s law
-Extension of an elastic object is DIRECTLY PROPORTIONAL to the FORCE applied to it
-Applies until ELASTIC LIMIT is exceeded
35
Elastic Limit
-Point at which PERMANENT DEFORMATION (Strain) occurs and the ELASTIC REGION ends
36
Plastic Region
-Force and deformation are NO LONGER PROPORTIONAL
-Small force increase = Large amount of deformation
-Material DIAMETER decreases until it fails and BREAKS
37
Young’s Modulus
-Method of measuring ELASTICITY of SOLIDS
-In the ELASTIC REGION the ratio of STRESS and STRAIN is constant
-This constant = Young’s Modulus
38
Compression
-Stress that SHORTENS or SQUEEZES material
-Compressive strength measured in N/m^2
39
Shear
-Stress that SLIDES one layer over another
-Tries to SLICE material
40
Clevis Bolts
-Designed to withstand SHEAR loads
41
Bending
-Stress caused by opposing COMPRESSION and TENSION stresses attempting to BEND a material
-eg Force of LIFT, compressing upper wing and tensioning lower wing causing wing to BEND UPWARDS
42
Torsion
-Stress that TWISTS material
-combination of COMPRESSION and TENSION acting DIAGONALLY at RIGHT ANGLES to each other.
43
Primary Stress on Propeller shafts
-TORSION caused by engine turning opposed by propeller resistance attempting to TWIST the Prop shaft.
44
Hardness in Solids
-Resistance to INDENTATION, PENETRATION and WEAR
-eg Diamonds, Cast Iron
45
Strength in Solids
-Tendency to withstand LOAD without FAILURE or PLASTIC DEFORMATION
-eg Steel, Titanium, Aluminium
46
Toughness in Solids
-Resistance to BREAKAGE when deforming or under IMPACT FORCE
-Do not have to be HARD. SOFT materials can be TOUGH
-eg Hammer head
47
Brittleness in Solids
-Tendancy to BREAK without changing shape
-Weak to SUDDEN or IMPACT Force
-Most materials become BRITTLE when COOLED
-TREATMENT can reduce brittleness and MAINTAIN DESIRABLE QUALITIES
-eg Concrete, Cast Iron and Room temp glass
48
Elasticity in Solids
-Tendency to RETURN TO ORIGINAL SHAPE when distorting Forces are removed
-OPPOSITE of Plasticity
-Each Solids has UNIQUE ELASTIC LIMIT
-eg Hard Steel, Mild + Medium carbon steel and Rubber
49
Plasticity in Solids
-Tendency to STAY IN NEW SHAPE when distorting Forces are removed
-VERY PLASTIC substances will change shape under LIGHT FORCE
-VERY HARD plastic materials require STRONG FORCE to change shape
-eg Lead, gold, aluminium, putty, plasticine and Wet Clay
50
Malleability in Solids
-Tendency to be UNDAMAGED by COMPRESSIVE STRESS
-Malleable materials can be BEATEN, ROLLED or PRESSED into a shape without FRACTURE/BREAKING
-eg Red hot steel, aluminium
51
Ductility in Solids
-Tendency to undergo TENSILE STRESS without damage
-WIRES require DUCTILE MATERIAL (Metal rods are drawn through steel dies during manufacturing)
-eg Copper, Gold, Silver and Steel
52
Fluid
Liquid, Gas or Vapour
53
Vapour
-Gas that can LIQUIFY with a PRESSURE INCREASE without a TEMPERATURE INCREASE
-Also name for Gas below its BOILING POINT
-eg Steam and Sodium Vapour
54
Volatile Liquid
-readily EVAPORATES at room temperature
-quickly occupies space above it with its VAPOUR
-will continue until completely evaporated in an OPEN CONTAINER
-eg Petrol, methylated spirits and Ethanol
55
Flammable/Inflammable
-CATCH FIRE readily
-often a property of VOLATILE LIQUID VAPOURS
-eg Fuels, Cleaning Fluids, some paints and dopes
56
Flash Point
-TEMPERATURE at which COMBUSTABLE liquid will catch fire when exposed to NAKED FLAME
-Lower Flashpoint = Easier to Ignite
57
Flash Point of Aviation fuel
38 degrees Celsius
58
Flashpoint of Petrol
-23 degrees Celsius
59
Toxicity
-How POISONOUS a substance is
-High Toxicity = Poison upon ingestion, inhalation or skin contact
-Usually identified with WARNING SIGNS on containers
-eg Mercury, Chlorine Gas, Arsenic or Biocides
60
Indications of contact with Toxins
-Skin Irritation
-Sore Eyes
-Feeling sick
-Difficulty Breathing
61
Inert
-will not CHEMICALLY COMBINE with another substance
-All Inert substances are GASES
-eg Helium, Neon and Argon
62
Atmospheric Pressure
-FORCE exerted by the WEIGHT of the ATMOSPHERE
-Can vary
63
Average Atmospheric pressure at sea level
-14.7 Psi
-also shown as 1 atmosphere (atm) on Barometers
64
Mercury Barometer
-Most common type
-Vertical glass tube closed at top sitting in open, Mercury filled basin at bottom
65
Gauge Pressure
-Amount of Pressure that measured fluid pressure exceeds ATMOSPHERIC PRESSURE by
-eg tire pressure gauge reading
66
Ambient Pressure
-Pressure in area immediately surrounding an object
-eg Static probe pressure
67
Absolute Vacuum
-Volume that doesn’t contain ANY particles
68
Absolute Pressure
-GAUGE PRESSURE + ATMOSPHERIC PRESSURE
-Uses ABSOLUTE ZERO as a reference point
-eg Barometric Pressure
69
Archimedes Principle
-A body in FLUID is subject to an UPWARD FORCE equal to the WEIGHT of the Fluid it DISPLACES
-Upward Force is known as BUOYANT FORCE
70
Buoyant Force
-Upward Force in ARCHIMEDES PRINCIPLE
-Equal to WEIGHT of the DISPLACED FLUID
-Measured in Newton’s or Pounds (N or Lb)
71
Example of Buoyancy in gases
-Hot Air balloon rising
-Heated Air is LESS DENSE than the cool air it DISPLACES
72
Floatation
-Height of float (positive, negative or neutrally buoyant) expresses as a RATIO
-Flotation ratio shows how much of object is BELOW the waterline
73
Uniform Motion
-Moving by the same distance over a given period of time
-This motion is at a CONSTANT SPEED
74
Constant Velocity
-Moving STRAIGHT at a CONSTANT SPEED (Not ACCELERATING)
-Velocity = change in DISPLACEMENT over TIME
75
Acceleration
-Object moving with a CHANGING VELOCITY (Not Constant)
-Occurs I’d object changes SPEED or DIRECTION
-In LINEAR MOTION, acceleration can only occur with a change in DIRECTION
76
Speed
-SCALAR Quantity (Not directional)
-Objects Moving In opposite direction can have SAME SPEED but DIFFERENT VELOCITIES
77
Centripetal Force
-Keeps objects moving in a CURVED PATH
-Directed towards CENTRE OF ROTATION
78
Centripetal Acceleration
-Result of CONSTANT DIRECTION CHANGE from centripetal Force
-direction change = ACCELERATION
79
Centrifugal Force
-opposite of CENTRIPETAL FORCE
-Acts from CENTRE OF ROTATION OUTWARDS
-Calculated same way as CENTRIPETAL FORCE
80
Pendulum
-Weight suspended in EARTH’S GRAVITY
-Free to PIVOT at its TOP END
-Swings when moved due to GRAVITATIONAL ACCELERATION
81
Pendulum Damping
-Resistive Forces (Friction and Air Resistance) that reduce the AMPLITUDE of the swing.
-Eventually STOPS the pendulum
-Used In aircraft to prevent DAMAGING VIBRATIONS
82
Vibrations
-Mechanical oscillations about an EQUILIBRIUM POINT
-Can be PERIODIC or RANDOM
-Sound and Vibrations linked via ACOUSTICS
83
Free Vibration
-Mechanical system set off with starting input and allowed to VIBRATE FREELY
-System will vibrate at NATURAL FREQUENCY and DAMP down to ZERO
-eg Swingset, tuning fork
84
Forced Vibration
-CONTINUOUS MOTION applied to system
-Vibrates at same frequency as APPLIED FORCE
-AMPLITUDE is dependant on the MAKEUP OF THE SYSTEM
85
Harmonics
-PERIODIC - repeats at STANDARD INTERVALS in a SPECIFIC MANNER
-Are SINUSOIDAL with CONSTANT AMPLITUDE
-Are represented as a SINE WAVE
86
Isothermal Expansion/Compression
-Temperature remains CONSTANT
-As volume INCREASES, Pressure DECREASES and vice versa
-Pressure x Volume is constant
87
Adiabatic process
-No heat transferred to or from system
-Process that occurs within insulative container
-A Fast process with no time for heat transfer is also Adiabatic
88
Adiabatic Expansion/Compression
-As Volume increases, Temperature decreases and vice versa
89
True Adiabatic
-Cannot exist
-Some heat is always lost to the environment
90
4 types of Thermodynamic Process
1.Isothermal - Constant Temperature
2.Isochoric - Constant Volume
3.Isobaric - Constant Pressure
4.Adiabatic - No heat transfer to or from the System
91
Engine Cycle
-Series of THERMODYNAMIC PROCESSES forming a CYCLE that converts HEAT into WORK
92
Reversible Thermodynamic Process
-Can be restored to INITIAL STATE without CHANGING SURROUNDINGS
-Must be in THERMODYNAMIC EQUILIBRIUM with surroundings
93
True Reversible Process
-Impossible
-Some heat always transferred with surroundings
-Is a HYPOTHETICAL PROCESS
94
Irreversible Thermodynamic Process
-CANNOT revert back to INITIAL STATE without CHANGING SURROUNDINGS
-Aka NATURAL PROCESS
-All naturally occurring processes are IRREVERSIBLE
95
Reciprocating Piston engine cycle
-NON FLOW processes convert HEAT into MECHANICAL ENERGY
-CONSTANT VOLUME, INCREASED PRESSURE
96
Gas Turbine engine Cycle
-FLOW processes that convert HEAT into MECHANICAL ENERGY
-CONSTANT PRESSURE, INCREASED VOLUME
97
4 phases of engine cycles
1.Induction
2.Compression
3.Combustion
4.Exhaust
98
4 processes of Otto Cycle (Piston Engine)
1. Adiabatic Compression (1 to 2): Piston moves from bottom to top, no heat transfer, Temp up, Pressure up, Volume down
2. Reversible Isochoric Heating (2 to 3): Piston at top, Ignition of fuel/air mix, temp up, Pressure up, volume constant
3. Adiabatic Expansion (3 to 4): High Pressure Forces Piston down, temp down, no heat transfer
4. Reversible Isochoric rejection (cooling) (4 to 1): Piston is at bottom, Pressure and temp decrease to initial levels
99
Phases skipped by Otto cycle (Piston engines)
-INDUCTION and EXHAUST phases
-Due to WORKING FLUID being CONSTANTLY REUSED
100
3 components required for Brayton cycle (gas turbine engines)
1. Gas Compressor
2. Mixing Chamber (Combustion Chamber)
3. Expander (Turbine)
101
4 Processes of Brayton cycle (gas turbine engines)
1. Adiabatic Compression (1 to 2): Fresh Air into compressor, No heat transfer, temp up, Pressure up, volume down
2. Isobaric Heating (2 to 3): compressed air into combustion chamber, fuel burned to heat air, pressure constant, temp up, volume up
3. Adiabatic Expansion (3 to 4): Air gives up energy as it expands through the turbine, some turbine work drives compressor, pressure down, temp down, no heat transfer
4. Isobaric Cooling (4 to 1): Air cools in atmosphere, volume and temp down to Initial levels
102
Constant volume process
-ISOCHORIC
-considered REVERSIBLE in a PERFECT GAS
-working fluid kept in RIGID CONTAINER
-system boundaries are IMMOVABLE, no work can be done on or by the system
-all heat supplied increases INTERNAL ENERGY of the WORKING FLUID
-eg BRAYTON CYCLE
103
Constant pressure process
-ISOBARIC
-REVERSIBLE process for a PERFECT GAS
-boundary of system NOT RIGID
-to keep CONSTANT PRESSURE, VOLUME must CHANGE
-boundary moves against EXTERNAL RESISTANCE as HEAT is supplied
-WORK is done by fluid onto its SURROUNDINGS
104
Latent Heat
-Heat absorbed or released during CONSTANT TEMPERATURE (ISOTHERMIC) Process
105
Latent Heat of Fusion
-Heat added causing solid to liquid state change
-eg when ice melts at 0 degrees Celsius, water and ice remain at 0 degrees until state change is COMPLETE
106
Latent Heat of Evaporation
-Heat added causing Liquid to Gas state change
-eg Boiling water at 100 degrees Celsius, steam and water remain at 100 degrees until state change is COMPLETE
107
Thermal Energy
-KINETIC ENERGY possessed by an object due to particles moving within it
-Allows for TEMPERATURE to be measurable
-Is the ability to do WORK
108
Heat of Combustion
-ENERGY releases as HEAT during COMPLETE COMBUSTION with OXYGEN
-Usually from hydrocarbon/organic molecule combusting
-CO2 and Water also released
-Heat level varies based off compound of FUEL
109
Light
-ELECTROMAGNETIC RADIATION visible to the human eye
110
Electromagnetic Waves
-MAGNETIC and ELECTRIC field travelling together
-Fields are DISPLACED at 90 DEGREES to each other
-Follow a SINUSOIDAL pattern (forming SINE WAVES)
111
Colour of Light
-Different FREQUENCIES or WAVELENGTHS of ELECTROMAGNETIC WAVES hitting the retina
-HIGH Frequency = BLUER until ULTRA-VIOLET
-LOW Frequency = REDDER until INFRA-RED
112
2 units to measure Light wavelengths
1. Nanometres
2. Angstroms
1 Angstrom = 0.1 Nanometres
113
Visible Light Range
-Range of 400-700 Nanometres
-X-rays and other equipment used to detect ELECTROMAGNETIC RADIATION outside this range
114
Speed of Light in a vacuum
-300,000,000 m/s
-3x10^8 m/s
115
If speed of light is not given
-Assume it is travelling through a vacuum
-3x10^8 m/s
-300,000,000 m/s
116
Reflection at Plane surface
-Angle of INCIDENCE is EQUAL to angle of REFLECTION
-NORMAL is PERPENDICULAR to the surface
-Incident Ray, reflected Ray and Normal are all in the SAME PLANE
117
Real image
-Can be PROJECTED onto a screen/wall
118
Virtual Image
-Can only be seen by LOOKING INTO OPTICS
-Light rays are perceived as originating from elsewhere
-eg perceiving mirror reflection as behind the mirror
119
Images formed in Plane mirrors
-Same size as object
-Percieved as same distance behind mirror as object is from from of mirror
-VIRTUAL
-LATERALLY INVERTED (text appears backwards)
120
Convex mirror
-Curves OUTWARDS
-Reflected rays DIVERGE
-Image appears SMALLER
-Reflection has WIDE FOV
121
Concave Mirror
-Curves INWARDS
-Reflected rays CONVERGE
-close up image = MAGNIFIED, UPRIGHT and VIRTUAL
-far away image = DIMINISHED, INVERTED and REAL
-eg magnified views in technology
122
Refraction
-CHANGE in DIRECTION of a WAVE when it enters a DIFFERENT MEDIUM
-Some Light REFLECTED back into first medium
-Direction change caused by change in SPEED OF LIGHT
-If Light is PERPENDICULAR to the surface it changes speed but NOT DIRECTION
123
Refractive Index
-Ratio of speed of light in VACUUM (3x10^8m/s) to speed of light in MATERIAL
-HIGH REFRACTIVE INDEX = More light bending, SLOWER speed of Light
124
Snell’s Law
-Describes relationship between ANGLE OF INCIDENCE and ANGLE OF REFRACTION.
-Used to determine REFRACTIVE INDEX of materials
125
Convex Lens
-CONVERGING Lens
-Curves OUTWARDS on BOTH SIDES
-May form REAL or VIRTUAL image depending on POSITION in relation to Lens
-eg Magnifying glasses, cameras and naturally in the EYE
126
Concave Lens
-DIVERGING Lens
-Curves INWARDS on BOTH SIDES
-Image formed is always UPRIGHT, VIRTUAL and DIMINISHED
-eg Spectacles, binoculars and Telescopes
127
Fibre optics
-DATA INFORMATION covered to a LIGHT SIGNAL travels through fibre cables
128
3 Advantages of Fibre optic cables
1. Light and Small
2. Carry more information
3. Safer (no fire risk)
129
2 Disadvantages of Fibre optic cables
1. Difficult to Terminate
2. Difficult to repair (Fibres thinner than human hair)
130
2 components of a fibre optic strand and their function
1. High refractive index Core
2. Low refractive index Cladding
-Light reflects off Cladding, remaining in Core, resulting in TOTAL INTERNAL REFLECTION and reducing signal loss over long distances
131
Mechanical Waves
-OSCILLATION of MATTER, requires MEDIUM to transmit ENERGY through
-eg Sound Waves (need Air molecules to exist)
132
2 types of Mechanical Wave
1. Transverse
2. Longitudinal
133
Transverse Mechanical wave
-Displacement of MEDIUM is PERPENDICULAR to direction of PROPAGATION of the WAVE
134
Longitudinal Mechanical wave
-Displacement of MEDIUM is PARALLEL to direction of PROPAGATION of the WAVE
-eg Sound waves
135
Sine Waves
-Have a PERIODIC WAVEFORM
-Repeat at a STANDARD INTERVAL
-Repeat in a SPECIFIC MANNER
-Have a CONSTANT AMPLITUDE
136
Amplitude of a Waveform
-Greatest Displacement from REST POSITION
-ie Peaks and Troughs of waves
137
Wavelength
-Distance from one point on wave to next point at SIMILAR POSITION
-eg PEAK to PEAK
138
Periodic time of waveforms
-Time taken to complete ONE OSCILLATION
139
Frequency of Waveform
-Number of COMPLETED OSCILLATIONS per SECOND
140
Which 2 waveform properties are Reciprocals of eachother? (Dividing 1 by one of them gives h value of the other)
-Periodic Time and Frequency
141
Interference Phenomena
-Formation of a RESULTANT WAVE of a DIFFERENT AMPLITUDE when 2 waves travelling through the SAME MEDIUM meet.
142
What is the Amplitude of the resultant wave when 2 sine waves of identical amplitude travelling towards eachother through the same medium meet?
-Double the Amplitude of one of the sine waves
143
Standing wave
-Combination of 2 waves of SAME AMPLITUDE and FREQUENCY moving in OPPOSITE DIRECTIONS
-Combination OSCILLATES in TIME but its PEAK AMPLITUDE PROFILE doesn’t move in SPACE
144
Progressive Waves
-Waves that move NORMALLY
145
Sound Waves
-VIBRATIONS through AIR or OTHER MEDIUM that can be detected by ELASTIC MEDIUM such as EAR DRUMS
146
Speed of Sound in room temperature air
343 m/s
147
Speed of sound in water
1500 m/s
148
Speed of sound in Bar of Steel
5000m/s
149
Mach Number
-Describes ratio of AIRCRAFT SPEED in relation to SPEED OF SOUND
-Aircraft speed/Speed of sound = Mach Number
150
2 Factors Loudness depends on
1. AMPLITUDE of Vibrations
2. DISTANCE from the SOUND SOURCE
151
Compression of Sound waves
-Areas of DENSE air cause LONGITUDINAL Sound waves to COMPRESS
152
Sound Intensity
-aka AMPLITUDE
-Expressed in terms of PRESSURE
-Quantified using LOGARITHMIC DECIBEL AMPLITUDE SCALE
153
Quietest Sound humans can hear
0 decibels
154
Sound intensity that cause damage with Prolonged exposure
85 decibels
155
Sound intensity that causes severe pain and permanent damage
130 decibels or higher
-eg jet engine
156
Unit of Sound Pressure Level (SPL)
-Decibels
157
Pitch of Sound
-Determines how SHRILL or DEEP sound is
-Determined by FREQUENCY
-High Frequency = High Pitch
158
Pitch of Tone
-Proportional to Number of COMPRESSIONS and RAREFACTIONS received PER SECOND
-Determined by VIBRATION FREQUENCY of the SOUND SOURCE
159
Quality of sound
-Used to distinguish between 2 sounds with SAME PITCH AND LOUDNESS
-eg 2 instruments of the same type
-Determined by variations in number and Intensity of OVERTONES
-Allows recognition of different HUMAN VOICES
160
Fundamental Frequency
-LOWEST Frequency tone produced
161
Overtones or Harmonics
-Other tones of higher frequency than FUNDAMENTAL FREQUENCY
-Used to Determined QUALITY OF SOUND
162
Doppler Effect
-Percieved pitch of Sound (such as siren) getting lower as it moves past you
-Present for all wave motion
-Moving Towards = SHORTER WAVELENGTHS, HIGHER PITCH
-Moving Away = LONGER WAVELENGTHS, LOWER PITCH
163
Viscosity
-RESISTANCE of a Fluid to change its shape
-OPPOSITION to FLOW
164
Liquid Viscosity
-DECREASES RAPIDLY as TEMPERATURE INCREASES
165
Gas Viscocity
-INCREASES as TEMPERATURE INCREASES
166
Fluid Resistance
-aka Fluid friction
-Occurs when Solids travels through liquid or gas
-eg WIND RESISTANCE
167
3 Factors effecting Fluid Resistance
1. VISCOSITY of Fluid
2. TEXTURE of Solid object
3. SHAPE of Solid object
168
Streamlining
-Decreasing amount of RESTRICTIVE FORCE from FLUID RESISTANCE
-eg Countersunk rivets or use of composites on Aircraft skin
169
If a Liquid is Compressable
-INCREASED PRESSURE = INCREASED INTERNAL TEMPERATURE
-INCREASED PRESSURE = REDUCED VISCOSITY
170
If a Gas is compressable
-INCREASED PRESSURE = INCREASED VISCOCITY
171
Fluid Pressure
-Determined by height of column of Liquid and type of Liquid
-More height = MORE PRESSURE
-Measuring halfway up column = LOWER PRESSURE
172
Pascal’s Law
-When PRESSURE is applied to a CONTAINED LIQUID, the liquid exerts an EQUAL PRESSURE at RIGHT ANGLES to the container
173
Static Pressure
-Exists IN ADDITION to any DYNAMIC FACTORS also present
-PASCAL’S LAW applies to Static Pressure
174
Dynamic pressure
-Formed as a result of the VELOCITY of a Fluid in MOTION
175
Total Pressure
-Sum of STATIC PRESSURE and DYNAMIC PRESSURE
176
Bernoulli’s Theorem
-POTENTIAL ENERGY and PRESSURE decrease when KINETIC ENERGY or VELOCITY Increase
177
Potential Energy in Fluids
-Result of FLUID PRESSURE
178
Venturi Tube
-Narrower In middle than at ends
-Has Higher Velocity and Kinetic energy in the central restriction but lower Pressure and Potential energy
-TOTAL EMERGY REMAINS THE SAME
-Used In gyroscopic Aircraft instruments
179
Temperature
-Measure of AVERAGE KINETIC ENERGY of particles
-Warmer = FASTER
-Property of system that determines if it is in THERMAL EQUILIBRIUM
180
Heat flow
-Transfer of Heat from HOTTER to COLDER body
-Usually occurs naturally until THERMAL EQUILIBRIUM is reached
181
3 types of Thermometer
1. Bulb (standard)
2. Bimetallic
3. Thermistor
182
Thermocouples
-Used to measure HIGH TEMPERATURES
-eg Measures EGT In Gas turbine Engines
183
Bulb Thermometer
-Contains Fluid such as Mercury
-Reads Temperature via FLUID EXPANSION
-Water Not Used As it will FREEZE/BOIL
184
Bimetallic Thermometer
-Shows Temperature via MECHANICAL DISPLACEMENT
-Functions via 2 different metals EXPANDING at different rates as they heat up
-Often Used In HEAT SENSORS or to read Free air temp and outside air temp in light aircraft
185
Thermistors
-THERMAL RESISTORS
-Most commonly used SENSOR
-COMPUTER measures RESISTANCE of material and converts it to a TEMPERATURE reading
186
Freezing point of Water in Fahrenheit
32 degrees Fahrenheit
187
Boiling point of Water in Fahrenheit
212 degrees Fahrenheit
188
Temperature at which Celsius and Fahrenheit read the same
-40 degrees
189
Kelvin
-Base unit of TEMPERATURE in SI UNITS
-0 Kelvin = ABSOLUTE ZERO
190
Absolute Zero
-Temperature at which all molecular movement CEASES
-Cannot actually be reached
-Classed as a LIMITING TEMPERATURE
191
Absolute Zero in Celsius
-273.15 degrees Celsius
192
Absolute Zero in Fahrenheit
-460 degrees Fahrenheit
193
calorie/Calorie
-calorie is ONE THOUSANDTH of a Calorie (CAPITAL C)
-Used to measure HEAT ENERGY in FOOD
194
What is required to move heat in reverse from a lower temperature body to a higher temperature body?
-WORK
195
3 methods of heat energy transfer
1. Conduction
2. Convection
3. Radiation (works in empty space)
196
Specific heat
-Amount of Heat needed to raise Temperature of 1kg of material by 1 degree Celsius
197
Heat capacity
-aka Thermal mass
-Ratio of HEAT ENERGY transferred to resulting TEMPERATURE increase
-Measurement of capability of a substance to ABSORB HEAT ENERGY
198
Heat Transfer
-Flow of Heat due to TEMPERATURE DIFFERENCES
-Subsequent TEMPERATURE CHANGES and DISTRIBUTION
199
Conduction
-Occurs in SOLIDS and FLUIDS
-Heat DIRECTLY TRANSFERRED through MATERIAL
-Atom and molecule VIBRATION carries energy
200
Convection
-FLUIDS ONLY
-Heat transfer from ONE PART OF FLUID TO ANOTHER
-eg Heat rising
201
Thermal Radiation
-Most efficient through a VACUUM
-Temperature INCREASE = AMOUNT and PEAK FREQUENCY of radiation INCREASES (eg iron going red to white hot)
-Substances DONT need to be in contact with eachother to transfer heat via radiation (eg SUN heating Earth)
202
Thermal Expansion/Contraction
-EXPAND when HEATED
-CONTRACT when COOLED
-HEAT = Molecule VIBRATION = Bigger gaps between molecules = EXPANSION
203
Coefficient of linear thermal expansion
1 degree Celsius
204
Linear Expansion
-Length changes by amount PROPORTIONAL to ORIGINAL LENGTH and CHANGE IN TEMPERATURE
205
Area Expansion
-Experienced by TWO-DIMENSIONAL SOLID BODIES
-WIDTH and HEIGHT change in MAGNITUDE
206
Volumetric Expansion
-HEIGHT, WIDTH and DEPTH change in MAGNITUDE
207
Matter states in order of Most to least thermal Expansion
1. Gases - Most room for molecules to VIBRATE APART
2. Liquids
3. Solids
208
First Law of Thermodynamics
-ENERGY cannot be CREATED or DESTROYED, only TRANSFORMED
-Energy In = Energy Out
209
Second Law of Thermodynamics
-The total ENERGY output provided by a MACHINE is equal to the amount of HEAT applied, some energy is WASTED
-HEAT supplied must be GREATER than WORK done by MACHINE
210
Entropy
-IRREVOCABLE loss of ENERGY to the ENVIRONMENT due to DISORDER in the system
-TOTAL ENTROPY in the Universe can only INCREASE or REMAIN THE SAME
211
Two types of Thermodynamic Cycles
1. OPEN
2. CLOSED
212
5 Basic elements of a Thermodynamic cycle
1. Working substance (eg Oil)
2. Heat source
3. Heat reciever
4. Pump
5. Engine (converts THERMAL ENERGY into WORK)
213
Open cycles
-OPENING in system BOUNDARY
-WORKING FLUID can be REGULARLY REPLACED
-Fluid TAKEN in and DISCARDED after each CYCLE
-eg Gas turbine engines
214
Closed cycles
-FIXED BOUNDARY containing FIXED AMOUNT of VAPOUR/GAS
-Fluid returns to INITIAL STATE after each CYCLE
-NO MASS TRANSFER
-Interchange of HEAT and WORK occurs
-eg Refrigerator
215
Ideal Gas
-Gas shown through experiments to adhere closely to IDEAL GAS LAWS
-eg Hydrogen, Oxygen, Nitrogen
216
Boyle’s Law
-ISOTHERMAL PROCESS
-At a CONSTANT TEMPERATURE, the PRESSURE exerted by a Gas varies INVERSELY with the VOLUME
-eg SMALLER VOLUME = HIGHER PRESSURE
217
Charles’ Law
-ISOBARIC PROCESS
-At a CONSTANT PRESSURE, the VOLUME of Ideal gas INCREASES in DIRECT PROPORTION to the TEMPERATURE INCREASE
-eg Higher Temperature = Bigger Volume
218
Gay-Lussac’s Law
-ISOCHORIC PROCESS
-At a CONSTANT VOLUME, the PRESSURE of Gas is DIRECTLY PROPORTIONATE to the ABSOLUTE TEMPERATURE
219
Specific heat at constant volume
-ISOCHORIC PROCESS
-No WORK is done
-Heat supplied only changes THERMAL ENERGY
220
Density
-How tightly particles are packed in a material (MASS per UNIT VOLUME)
-Liquids and solids have similar density
-Gases have MUCH LOWER density
-Density varies between materials
221
Specific Gravity
-aka RELATIVE DENSITY
-Used to compare density of 2 substances
-Is a RATIO and has NO UNIT
222
What are all Liquids and Solids compared to in regards to Specific Gravity?
-Water At 4 degrees Celsius
223
What are all gases compared to in regards to Specific Gravity?
-Air At room temperature (20 degrees Celsius)
224
Hydrometer
-Used to measure SPECIFIC GRAVITY of LIQUIDS
-Glass float within larger glass tube filled with test liquid
-Float is weighted and has VERTICAL SCALE which can be read off the SURFACE of the test liquid
225
Pure Water Hydrometer reading
-1000
-Specific Gravity = 1
226
Charged Battery Electrolyte Hydrometer reading
-1275 to 1310
-SPECIFIC GRAVITY = 1.275-1.31
227
Discharged battery electrolyte Hydrometer reading
-1150
-Specific Gravity = 1.15
228
Harmonic Series
-1st Harmonic = The FUNDAMENTAL
-2nd Harmonic = 1st OVERTONE
-3rd Harmonic = 2nd OVERTONE
-etc
229
Resonance
-Tendency for system to oscillate at its MAXIMUM AMPLITUDE when at its RESONANT FREQUENCY
230
Velocity Ratio
-How far EFFORT has to move in relation to LOAD
-Has NO UNIT
-If Velocity Ratio is GREATER THAN 1, then the distance moved by the POINT OF EFFORT is greater than the distance moved by the LOAD
231
Mechanical Advantage
-RATIO of FORCE PRODUCED in relation to FORCE APPLIED
-Has NO UNIT
232
Actual Mechanical Advantage
-RATIO of OUTPUT FORCE in relation to INPUT FORCE
-Has NO UNIT
233
Ideal Mechanical Advantage
-RATIO of INPUT DISTANCE in relation to OUTPUT DISTANCE
-Represents Mechanical Advantage that would exist with NO FRICTION in the MACHINE
234
Inclined Plane
-SURFACE inclined at any angle EXCEPT RIGHT ANGLE
-Allows LARGE RESISTANCE to move a long distance with LESS EFFORT
235
Single, fixed pulley
-IDENTICAL to FIRST CLASS LEVER
-MECHANICAL ADVANTAGE = 1
236
Single, moving pulley
-Moves in same direction as WEIGHT
-IDENTICAL to SECOND CLASS LEVER
-MECHANICAL ADVANTAGE = 2
-eg Input Force of 50N = Output Force of 100N
237
Calculating combined Pulley Mechanical Advantage
-Count the ropes acting on the MOVING PULLEY
238
Calculating combined pulley rope length
-Multiply MECHANICAL ADVANTAGE by DESIRED MOVEMENT
239
Mechanical advantage in gears
-Depends on NUMBER OF TEETH
-If same number of teeth, MA = 1
-If DRIVEN gear has twice the teeth of DRIVE gear, MA = 2 etc
240
Gear Ratio
-Ratio of Driven gear teeth:Drive gear teeth
-Simplify if possible (eg 16:8 to 2:1)
241
Revolution Ratio
-OPPOSITE OF GEAR RATIO
-Ratio of Drive Gear teeth:Driven gear teeth
242
Spur Gears
-Teeth cut STRAIGHT ACROSS circumference
-connect 2 PARALLEL shafts
-If both have EXTERNAL teeth, shafts turn OPPOSITE directions
-If one has INTERNAL teeth, shafts turn SAME direction
243
Bevel Gears
-Teeth cut into comical surface known as PITCH ZONE
-Connects two shafts at AN ANGLE to eachother
-Used when drive and driven shafts are NOT PARALLEL
-Teeth are always EXTERNAL, shafts turn OPPOSITE directions
-Angle Usually 90 degrees but can be up to 180
244
Worm gears
-Toothed wheel driven by revolving WORM CYLINDER
-Worm has SCREW THREAD
-Used for large REDUCTION SPEED and HIGH TORQUE MULTIPLICATION applications
245
Sun and Planet Gears
-SUN gear with INPUT DRIVE
-PLANET gears held by CAGE and rotate around SUN gear and FIXED OUTER RING GEAR
-OUTPUT comes from CAGE which rotates in SAME DIRECTION as SUN gear but rotates SLOWER
-Used for LARGE SPEED REDUCTION and HIGH TORQUE applications
246
Efficiency
-RATIO of WORK transferred to USEFUL FORM vs TOTAL INPUT WORK
-Expressed as a PERCENTAGE
247
Newton’s Second Law
-The ACCELERATION of an object produced by a FORCE is DIRECTLY PROPORTIONAL to the FORCE, is in the SAME DIRECTION as the FORCE, and is INVERSELY PROPORTIONAL to the MASS of the object
-F = m x a
248
Gravitational Acceleration
9.81 m/s^2
249
Newton’s Third Law
-Every ACTION has an EQUAL AND OPPOSITE REACTION
250
Mass
-Amount of MATTER in a body regardless of VOLUME or POSITION
251
What is 1kg In Amu?
6.02x10^26Amu
252
Weight
-GRAVITATIONAL FORCE of ATTRACTION between MASS OF EARTH and the MASS OF A BODY
-DECREASES as body moves AWAY from EARTHS CENTRE
253
What does a 750N body at the North Pole weigh at the Equator?
745N
254
Inertia
-RESISTANCE to change in STATE OF REST or MOTION triggered by a FORCE
-Greater MASS = Greater INERTIA
255
Work
-FORCE causing MOVEMENT or DISPLACEMENT
-Increased FORCE = Increased WORK
-Increased DISTANCE MOVED = Increased WORK
256
Power
-RATE at which WORK is done over TIME
-Measured in Watts(W), horsepower(hp) or metric horsepower (PS)
257
Mechanical Energy
-ENERGY held by a body after WORK has been done
-Combination of KINETIC and POTENTIAL energy
258
Potential Energy
-ENERGY body holds due to POSITION/CONDITION (does WORK when released)
259
Gravitational Potential Energy
-Form of POTENTIAL ENERGY that INCREASES as a body is LIFTED
-Dependant on GRAVITATIONAL ACCELERATION (9.81m/s^2), MASS and HEIGHT
260
Kinetic Energy
-ENERGY body has due to MOTION
-Faster MOTION = higher KINETIC ENERGY
-Object AT REST has NO KINETIC ENERGY
-Depends on MASS and VELOCITY
261
Total Energy
-SUM of ALL ENERGY in a system
-Energy Cannot be CREATED or DESTROYED
-Energy CHANGES FORM but TOTAL ENERGY remains THE SAME
262
Chemical Energy
-ENERGY stored in the CHEMICAL BONDS between ATOMS
-Released or consumed via CHEMICAL REACTION (BONDS changing)
-Is a form of POTENTIAL ENERGY
263
Momentum
-VECTOR QUANTITY describing MASS in MOTION
-Depends on MASS and VELOCITY
-More MASS or VELOCITY = more MOMENTUM
-Direction of MOMENTUM same as direction of VELOCITY
264
Momentum in a closed system
-Total momentum before event = total momentum after event
265
Collision
-Two bodies INTERACT, transferring KINETIC ENERGY and MOMENTUM
-Total MOMENTUM always CONSERVED
-Total KINETIC ENERGY may CHANGE
266
2 Types of Collision
1. ELASTIC: Kinetic Energy CONSERVED, No HEAT or DEFORMATION
2. INELASTIC: Kinetic Energy CHANGES, HEAT and DAMAGE occur
267
Impulse
-VECTOR quantity
-IMPULSE of a FORCE changes the MOMENTUM of a body
-Equal to FORCE multiplied by the TIME the FORCE acts on the body
268
2 Vital gyroscopic principles
1. RIGIDITY
2. PRECESSION
269
Rigidity
-RETAINS SPIN AXIS unless acted on by an EXTERNAL FORCE
-Caused by INERTIA
-aka Gyroscopic Inertia
270
4 factors affecting Rigidity/Gyroscopic Inertia
1. Rotor Mass
2. Effective radius at which mass acts
3. Speed of rotation
4. Bearing friction
271
Precession
-RESISTS attempts of EXTERNAL FORCE to change DIRECTION of ROTOR SPIN AXIS
-Moves FORCE at RIGHT ANGLES to ORIGINAL APPLIED DIRECTION
272
Starting Friction
-aka STATIC FRICTION/BREAK-AWAY FORCE
-Present when RESTING BODY begins to MOVE
-Amount depends on nature of MATERIAL SURFACES
273
Sliding Friction
-Present As body SLIDES over another surface
-Always LESS than STARTING FRICTION
-Present In bodies ALREADY IN MOTION
-Amount depends on NATURE OF MATERIAL SURFACES
274
Rolling Friction
-Present between ROLLING BODY and the surface it ROLLS over
-MUCH SMALLER than SLIDING FRICTION (Less RESISTANCE)
275
Coefficient of Friction
-Every PAIR of FLAT SURFACES have 2 DIFFERENT coefficients of friction
-STARTING FRICTION = greatest coefficient
-SLIDING FRICTION = smaller coefficient
-ROLLING FRICTION = smallest coefficient
