Definitions Flashcards
1
Q
Displacement
A
Distance moved in a particular direction (Straight line)
2
Q
Velocity
A
Rate of change of displacement with time m/s
3
Q
Speed
A
Distance/Time m/s
4
Q
Average velocity
A
Displacement/Time
u+v/2
5
Q
Instaneous velocity
A
Speed at the moment in time
6
Q
Constant velocity
A
Object doesn’t speed up or slow down or change direction
7
Q
Acceleration
A
Change in velocity with respect to time
8
Q
Scaler
A
Magnitude but no direction
9
Q
Vector
A
Magnitude and direction
10
Q
Momentum
A
How hard it is to stop an object that is moving
p=mv
11
Q
Conservation of momentum
A
Momentum before = momentum after if no external forces acts on the bodies
12
Q
Formula of conservation of momentum
A
m1u1+m2u2=m1v1+m2v2
13
Q
Newton’s First Law
A
An object will remain at rest or travels at constant velocity unless an external resultant force acts on it
14
Q
Newton’s Second Law
A
The rate of change of a body’s momentum will be proportional to the net force applied and will act in the direction of the force
F=ma
15
Q
Newton’s Third Law
A
Every action has an opposite but equal reaction
16
Q
Force
A
Anything that makes an object move or change velocity
F=MA
17
Q
Friction
A
The force that opposes motion between two surfaces that are in contact
18
Q
Mass
A
The amount of matter in an object
19
Q
Terminal velocity
A
The constant velocity of a falling object when the force of air resistant is equal in magnitude and opposite in direction to the force of gravity
20
Q
Newton’s Universal Law of Gravitation
A
Every mass in the universe attracts every other mass with a force along the line of their centres, that is proportional to the product of their mass and inversely proportional to the square of the distance between them
21
Q
Inverse square law
A
If the distance is doubled the force is four times smaller
22
Q
Universal gravitation forumula
A
F=Gm1m2/d^2
23
Q
Weight
A
A measure of the force of gravity on an object
W=mg
24
Q
Density
A
Mass per unit volume (kg m^-3)
25
Pressure
Force per unit area
F=P/A
P = ρgh
26
Boyle's Law
The volume of a fixed mass of a gas is inversely proportional to its pressure, as long as temperature is constant
27
Archimedes' principle
Whenever an object is totally or partially submerged in a fluid, it experiences an upthrust that is equal to the weight of the fluid it displaces
28
Law of flotation
Whenever an object is floating, the weight of the fluid displaced will equal the object's weight
29
Lever
A rigid bar that is free to rotate about a fixed fulcrum
30
Moment of a force
Magnitude of the force multiplied by the perpendicular distance from the axis to the force
31
Couple
A pair of equal parallel forces that turn in opposite directions
32
Work
The energy given to a body by a force moving it through a displacement in the same direction as the applied force
W=Fs
33
Energy
The ability to do work
34
Law of conservation of energy
Energy cannot be created or destroyed but is converted from one form to another
35
Potential energy
Energy due to position or properties and forces acting on it
mgh
36
Kinetic energy
Energy due to movement
1/2mv^2
37
Power
Work/Time
38
Efficiency
Useful energy/ Total energy
39
Heat
Amount of energy supplied to an object
40
Temperature
Measure of the hotness or coldness of an object
41
Thermometric property
Physical property that changes measurably and repeatedly with temperature change
42
Heat Capacity
Heat capacity of an object is the energy required to change its temperature by 1 kelvin
Q = CΔθ
43
Specific heat capacity
The energy require to change 1kg of the substance by 1 kelvin
Q = mcΔθ
44
Latent heat
The heat energy required to change an objects state without a change in temperature
45
Specific latent heat
The heat energy require to change the state of 1kg of the substance without a change in temperature
Q=ml
46
Conduction
Transfer of heat energy in a solid by passing on kinetic energy from molecule to molecule
47
Convection
Transfer of heat energy by the circulation of the heated parts of a liquid or gas
48
Radiation
The transfer of heat energy as electromagnetic waves without the need of a medium
49
Solar constant
The amount of solar energy striking 1m^2 of the Earth's atmosphere every second
50
U-value
The amount of heat energy that can be transmitted across 1m^2 of its surface every second, as long as there is temperature difference of !K each side of the material
51
Normal
Line perpendicular to a surface at the incident point
52
Plane
Two dimensional surface
53
Law of reflection
The incident ray, reflected ray and normal ray all lies in the same plane
The angle of incidence i equals the angle of reflection r
54
Real image
An image cause by the actual intersection of light rays
55
Virtual image
An image cause by the apparent intersection of light rays
56
Parallax
The difference in the apparent position of an object viewed along two different line of sight
57
Refraction
Bending of light at a boundary as it passes from one transparent medium to another
58
Laws of refraction (Snell's Law)
The incident ray, refracted ray and normal all lie in the same plane
The ratio of the sine of the angle of incidence i to the sine of angle refraction r is a constant This constant is called the refractive index
59
Critical angle
The angle of incidence in the denser medium that results in an angle of refraction of 90 degrees in the rarer medium
60
Total internal reflection
Occurs when light ray, travelling from a denser medium to a rare medium at an incident angle greater than the critical angle is completely reflected
61
Power of lens
Its ability to converge or diverge light rays
P= 1/f
62
Long sighted
See distant objects more clearly than close objects
63
Short sighted
See close objects more clearly than distant objects
64
Mechanical waves
Require a medium to travel through and physically disrupt that medium
65
Electromagnetic waves
Don't require a medium to travel through and cause electric and magnetic disruption
66
Travelling waves
Carry energy through a medium without any overall movement of the medium
67
Longitudinal wave
Direction of vibration is parallel to the direction in which the wave is travelling
68
Transverse wave
The direction of vibration is perpendicular to the direction in which the wave is travelling
69
Reflection (Wave)
The bouncing of a wave off an object
70
Refraction (waves)
Bending of a wave as it enters a different medium and changes speed
71
Diffraction
Spreading out of a wave as it moves through a gap or around an obstacle
72
Interference waves
Combine to form a resultant amplitude made up of each wave's individual amplitude
73
Polarisation
A wave is confined to a particular plane
74
Stationary waves
Waves of the same frequency and amplitude that constructively and destructively interfere to produce a wave pattern in a confined space
75
Doppler effect
Apparent change in frequency due to the relative motion of source and observer
76
Pitch
Frequency of a note
77
Loudness
Amplitude of a note
78
Quality
The relative strength and numbers of overtones present
79
Overtones
Integer multiples of the fundamental frequency. The First overtone is 2f.
80
Harmonics
Integer multiples of the fundamental frequency. The first harmonic is at f.
81
Intensity of sound
The rate of sound energy incident on 1M^2 at a right angle to the direction of the motion of the sound
I=P/A
82
Dispersion of light
The separating of light into its different colours
83
Primary colours
The 3 colours that combine to make white light
Red, green and blue
84
Secondary colours
Combining 2 primary colours in equal amount magenta, cyan and yellow
85
Complementary colours
Primary and secondary colours that combine to give white light
86
Hydrometer
Denser the liquid is, more of the hydrometer will float higher. A scale can be put on the side and the density of liquid can be measured
87
Length of a column of liquid
Liquid expands when heated
If its placed in a thin tube, length of the column increases as the liquid expands and decreases as the liquid cools and contract
88
Electrical resistance
The resistance of a conductor changes with temperature
When temperature increase the resistance of metal increases as well this is due to molecules vibrating more and collide more with the electrons trying to pass through
89
Emf of a thermocouple
If 2 different metals are joined together to form a circuit and the two junctions are at different temperatures a small emf appears which can be measured by a very sensitive voltmeter.
Greater the temperature the greater the emf
90
Colour
Colours of certain crystals can change with temperature
91
Volume of gas at constant pressure
As a gas is heated it expands and if the pressure is kept constant the volume of gas will increase in proportion to the increase in temperature
92
Pressure at a constant volume
If a fixed mass of a gas is to have the same volume when heated then pressure would increase. The higher the temperature the greater the pressure required to maintain the same temperature
93
Tog value
Measure of the insulating ability of a piece of clothing
94
Convex mirror
A ray which strikes the pole is reflected back at an equal angle
A ray strikes the mirror parallel to the principles axis is reflected as if it came from the focus
95
Optical fibre
Very thin transparent rod which light can travel through by total internal reflection
96
Concave mirror
Parallel to the principle axis is reflected through the focus
Ray which strikes the pole is reflected at the same angle
97
Convex lenses
A ray which strikes the optic centre will pass straight through the lens
A ray travelling parallel to the principal axis passes through the focus on the other side
98
Concave lenses
A ray which strikes the optic centre passes straight through
A ray which strikes the lens travelling parallel to the principle axis is refracted as if it came from the focus
99
Constant wave phase
2 source are emitting waves that are a definite fixed amount out of step with each other
100
Coherent sources
2 sources of periodic waves are in phase or there is a constant phases differences between them
101
Period of a wave
Time taken for a particular point to undergo one complete oscillation
102
Frequency of a wave
The number of oscillations passing a particular point per second
103
Speed of a wave
Equal to the frequency multiply by the wavelength
c=f x landau
104
Frequency limits of audibility
20Hz - 20000Hz
105
Natural frequency
When object is free to vibrate it does so at certain frequency - one of these frequencies is more likely to occur than others
106
Resonance
If frequency of a periodic force applied to a body is the same as or very near to its natural frequency that body will vibrate with a large amplitude
107
Diffraction grating
Transparent material where the distance between the slits is very lose together so that it is close to the wavelength of light and a clear pattern will form
108
Formula for mirrors
1/f = 1/u + 1/v
f = focal length
u =object length
v = image length
109
Magnification formula
m = v/u
v - image height
u - object height
110
Reflective index
n= sini / sinr
n = speed of light in air / speed of light in material
n = real depth / apparent depth
111
Intensity
Power/ Area
112
Use of concave mirror
Searchlight
Projectors
Dentists mirror
113
Use of convex mirrors
In shops to detect shoplifters
Door mirror of cars
At concealed entrances to give view of oncoming traffic
114
Uses of Optical fibre
Transmit telephone signals
Endoscope
Dentist's drill
115
Two lenses in contact
Overall power of the lenses are the sum of each of the individual lenses
P= P1+P2
116
nodes
Points at rest
117
Anti nodes
Points at maximum amplitude
118
Threshold of hearing
Smallest sound available at 1KHz to the human ear to 10.12 W/m-2
