1
Q
Physical Quantity
A
A quantity that can be measured and consists of a numerical magnitude and a unit.
2
Q
Oscillation
A
A complete to-and-fro motion of an object
3
Q
Period
A
Time taken for a complete oscillation
4
Q
Scalar Quantity
A
Physical quantity that has magnitude only
5
Q
Vector Quantity
A
Physical quantity that possess both magnitude and direction
6
Q
Speed
A
Distance moved per unit time
7
Q
Displacement
A
Distance travelled in a specified direction
8
Q
Average speed
A
Total distance travelled over time
9
Q
Velocity
A
Rate of change of displacement
10
Q
Acceleration
A
Rate of change of velocity
11
Q
Uniform Acceleration
A
Constant rate of change of velocity
12
Q
Free Fall
A
An object can only be in free fall if the only force acting on it is its own weight
13
Q
Contact Forces
A
Forces which exist between objects that are in contact
14
Q
Mass
A
A measure of the amount of matter or substance in an object
15
Q
Weight
A
Gravitational force acting on a mass
16
Q
Gravitational Field
A
A region in which a mass experiences a force due to gravitational attraction
17
Q
Gravitational Field Strength
A
The gravitational force acting per unit mass on an object
18
Q
A force
A
A push or a pull that one object exerts on another
19
Q
Newton’s 1st Law of Motion
A
Every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it
20
Q
Inertia
A
Reluctance of the object to change its state of rest or motion due to its mass
21
Q
Newton’s 2nd Law of Motion
A
When a resultant force acts on an object of constant mass, the object will accelerate and move in the direction of the resultant force. The product of the mass and acceleration of the object is equal to the resultant force.
22
Q
1 Newton (1 N)
A
The force that will produce an acceleration of 1ms^-2 on a mass of 1kg
23
Q
Newton’s 3rd Law of Motion
A
For every action, there is an equal and opposite reaction.
When body A exerts a ___ force on body B, body B exerts an equal and opposite ___ force on body A.
24
Q
Friction
A
A force that opposes sliding motion between two surfaces in contact.
25
Moment of a force
The product of force and the perpendicular distance from the pivot to the line of action of the force.
26
Principle of Moments
When a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot.
27
Centre of Gravity
The point through which its whole weight appears to act.
28
Stability
The ability of an object to return to its original position after it is slightly displaced.
29
Energy
The capacity to do work.
30
Principle of Conservation of Energy
Energy can neither be created nor destroyed. It can be converted from one form to another or transferred from one body to another. Total energy in an isolated system remains constant.
31
Work Done
Work Done by a constant force on an object is given by the product of the force and the distance moved by the object in the direction of the force.
32
One Joule
The amount of work done by a force of 1N which moves an object through a distance of 1m in the direction of the force.
33
Gravitational Potential Energy
The energy in which a body possesses because of its position relative to the ground.
34
Kinetic Energy
The energy a body possessed due to its motion.
35
Power
The rate of work done or rate of energy converted.
36
Efficiency
The ratio of useful energy (or power) output over the total energy (or power) input and is usually expressed as a percentage.
37
One Watt
The rate of work done or energy conversion of one joule per second.
38
Renewable Energy
Energy from sources that can be replenished naturally.
39
Pressure
Force per unit area.
40
Density
Mass per unit volume of a substance.
41
Atmospheric Pressure
The weight of a layer of air that acts on the Earth per unit area.
42
The source of a wave is a…
Vibration or Oscillation
43
A Wave is a…
Disturbance that propagates through space, transferring energy with it but not matter.
44
The direction of vibration of a **transverse** wave
Perpendicular to the direction of wave travel.
45
The direction of vibration of a **longitudinal** wave
Parallel to the direction of wave travel.
46
Crest
The highest point of a transverse wave.
47
Trough
The lowest point of a transverse wave.
48
What does it mean for two points to be in phase?
Any two points in a wave are said to be in phase if they move in the same direction and have the same speed and have the same displacement from the rest position.
49
Wavelength
The shortest distance between any two points in a wave that are in phase.
50
Amplitude
Maximum displacement of a point of a wave from rest position.
51
Frequency of a wave…
Is the number of oscillations each point completes per second.
52
Period (Wave)
The time taken for each point on the wave to complete one oscillation. This is also the time taken to produce one complete wave.
53
Wavefront
An imaginary line on a wave joining all adjacent points in phase.
54
What is sound produced by?
Sound is produced by vibrating sources placed in a medium which produce regions of compression and rarefaction.
55
Compressions
Regions of high pressure due to particles being close together.
56
Rarefactions
Regions of low pressure due to particles being spread further apart.
57
Echo
Reflected sound from a surface heard after an interval of silence.
58
State one way of finding the amplitude of a sound wave.
Finding the maximum pressure change.
59
Ultrasound
Sound with frequencies above the upper limit of the human range of audibility (20,000 Hz)
60
Pitch of a wave depends on…
The frequency of the wave. Higher frequency = Higher pitch.
61
Loudness of a wave depends on…
The amplitude of the wave. Higher amplitude = Louder sounds.
62
Kinetic model of matter is known as…
Tiny particles in continuous motion.
63
Brownian motion.
The random motion of particles suspended in a fluid (gas or liquid).
64
Heat
The amount of thermal energy that is transferred from a hotter to a colder region.
65
Conduction
The process of thermal energy being transferred through a medium from one particle to another without any flow of the medium.
66
Convection
The transfer of thermal energy by means of convection currents in a fluid (gas or liquid), due to a difference in density.
67
Radiation (thermal energy)
The transfer of thermal energy in the form of electromagnetic waves such as infrared radiation without the aid of a medium.
68
What does Internal Energy consist of?
Kinetic energy (due to the motion of particles) and potential energy (due to the intermolecular forces) present in the molecules of a substance.
69
Heat Capacity
The amount of thermal energy required to raise the temperature of a body by 1K or 1 degree celcius (unit).
70
Specific Heat Capacity
The amount of thermal energy required to raise the temperature of unit mass of a material by 1K or one degree celcius (unit).
71
Latent Heat
Energy released or absorbed during a change of state, without a change in temperature.
72
Latent Heat of Fusion of a Solid
Amount of thermal energy required to change it from solid to liquid state, or vice versa, without any change in temperature.
73
Specific Lantent Heat of Fusion of a Solid
The amount of thermal energy required to change a unit mass of the solid to liquid, or vice versa, without a change in temperature.
74
Latent Heat of Vaporisation of a Substace
Thermal energy required to change it from liquid to vapour state, or vice versa, without any change in temperature.
75
Specific Latent Heat of Vaporisation of a Substance
Thermal energy required to have unit mass of a substance from liquid to vapour state, or vice versa, without any change in temperature.
76
Condensation
A change of state of a substance from gas to liquid and energy is released.
77
Boiling
A process whereby a liquid changes to gas at constant temperature (its boiling point).
78
Evaporation
A change of state of a substance from liquid to gas below boiling point.
79
Freezing
A change of state when a substance changes from liquid to solid without any change in temperature.
80
Melting
A change of state when a solid changes to a liquid upon heating at a constant temperature.
81
First Law of Reflection
The incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
82
Second Law of Reflection
The angle of incidence is equal to the angle of reflection.
83
Angle of Reflection
The angle between a reflected ray and the normal at the point of incidence.
84
Refraction
The bending of light as it passes from one optical medium to another.
85
Angle of Refraction
The angle between refracted ray and the normal at the point of incidence.
86
Refractive Index of a Medium
The ratio of speed of light in vacuum to the speed of light in that medium.
87
Optically Dense
Light travels slower in an optically denser medium than less optically dense medium.
88
First Law of Refraction
The incident ray, refracted ray and the normal at the point of incidence all lie in the same plane.
89
Second Law of Refraction
For two given media, the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is a constant, that is, sin i/sin r = constant.
90
Principle of Reversibility of Light Rays
Regardless of how many times a light ray has been reflected or refracted, it will follow the same path when its direction is reversed.
91
Critical Angle
The angle of incidence in the optically denser medium for which the angle of refraction in the less dense medium is 90 degrees.
92
Total Internal Reflection
The complete reflection of a light ray in an optically denser medium at the boundary with an optically less dense medium.
93
Focal Length
The distance between the optical centre and the principal focus point lens.
94
Focal Plane
The plane perpendicular to the principal axis on which all parallel rays meet after passing through the lens.
95
Optical Centre
The point on the principal axis that is midpoint between the surfaces of the lens.
96
Principal Axis
The line passing through the centre of the lens and which is perpendicular to the plane of the lens.
97
Principal Focus
The point on the principal axis where all the rays parallel to the principal axis meet after passing through all the lens.
98
Real Image
An image formed by a lens that can be captured on a screen. It is formed by the actual intersection of light rays.
99
Virtual Image
An image formed by a lens/mirror that cannot be captured on a screen. It is NOT formed by the actual intersection of light rays.
100
Normal (Light)
A line that is perpendicular to the reflecting or refracting surface at the point of incidence.
101
Electrostatics
The study of static electric charges.
102
Laws of Charges
Like charges repel and unlike charges attract.
103
Electrostatic Induction
The process of charging a conductor without any contact with the charging body.
104
Electric Field
A region where an electric charge experiences an electric force.
105
Direction of an Electric Field
Can be defined as the direction of the force on a small positive charge.
106
Strength of an Electric Field
Indicated by how close the field lines are to each other.
107
Electric Current
Measure of the rate of flow of electric charge.
108
1 Amphere
The flow of 1 column of charge per second.
109
Electromotive Force of an Electrical Source
The work done by the source in driving a unit charge around a complete circuit.
110
Potential Difference across a Component in an Electric Circuit
Work done by the source to drive a unit charge through the component.
111
Resistance of a Metallic Component
The ratio of the potential difference across it to the current flowing through it.
112
Ohm’s Law
Current passing through a metallic conductor is directly proportional to the potential difference across its ends, provided the physical conditions are constant.
113
Series Circuit
A connection where the components are connected one after another in a single loop and there is only one path through which electric current can flow.
114
Parallel Circuit
A connection where there is more than one path through which current can flow.
115
Potential Divider
A line of resistors connected in series. It is used to provide a fraction of the voltage of a source to another part of the circuit.
116
Transducers
Electrical or electronic devices that convert energy from one form to another.
117
Input Transducers
They convert non-electrical energy to electrical energy.
118
Output Transducers
They convert electrical energy to other forms of energy.
119
Thermistor
A device whose resistance varies with temperature.
120
Light-dependent Resistor
A device whose resistance varies with amount of light shining on it.
121
Alternating Current
An electric current that periodically reverses its direction and changes its magnitude in a circuit.
122
Voltage of Live Wire (Brown)
Usually High voltage like 240V in Singapore.
123
Voltage of Neutral Wire (Blue)
Usually Zero voltage.
124
What is the Earth Wire (Green and Yellow)?
A low-resistance wire which is connected to the metal casing of the appliance. The other end of the earth wire is connected to the earth so that any leakage of large current will be directed to the ground.
125
Circuit Breakers
Safety devices that can switch off the electrical supply in a circuit when there is an overflow of current.
126
Fuse
A safety device included in an electrical circuit to prevent excessive current flow by breaking the circuit.
127
Double Insulation
A safety feature in electrical appliances. They normally use two-pin plug (only live and neutral wire). The electric cable is insulated from the internal components of the appliance and the internal components are also insulated from the external casing (normally plastic).
128
Law of Magnetism
Like poles repel, unlike poles attract.
129
Magnetic Induction
The process whereby an object made of a magnetic material becomes a material when it is near or in contact with a magnet.
130
Magnetic Domain
A group of atomic magnets pointing in the same direction.
131
Magnetic Field
A region in which a magnetic object, placed within the influence of the field, experiences a magnetic force.
132
Soft Magnetic Materials
Magnetic materials which are easily magnetised but do not retain their magnetism.
133
Hard Magnetic Materials
Magnetic materials which are harder to magnetism but retain their magnetism.
134
How is Motor Effect produced?
Motor Effect is produced when a current carrying conductor is placed in a magnetic field.
135
D.C. Motor
A device that converts electrical energy to mechanical energy.
136
Electromagnetic Induction
A process through which an induced e.m.f is produced in a conductor due to a changing magnetic field.
137
Faraday’s Law
The magnitude of the induced emf in a circuit is directly proportional to the rate of change of magnetic flux in the circuit.
138
Magnetic Flux
The magnetic field in a given area.
139
Lens’s Law
The direction of the induced emf and hence the induced current in a closed circuit, is always such that it’s magnetic effect opposes the motion or change producing it.
140
Transformer
A device that can change a high alternating voltage to a low alternating voltage, or vice versa.
141
Proton or Atomic Number
The number of protons in an atom.
142
Nucleon or Mass Number
Total number of neutrons and protons in the nucleus of an atom.
143
Nuclides
Atoms whose nuclei contain a particular number of protons and neutrons.
144
Isotopes
Atoms of the same element that have the same number of protons but different numbers of neutrons.
145
Nuclear Decay or Radioactive Decay or Radioactivity
A random process by which an unstable atomic nucleus loses its energy by emission of electromagnetic radiation or particles.
146
Properties of Radioactive Decay
Radioactive Decay is spontaneous as it happens by itself without any external influence.
Radioactive decay is random over space and time. Where (which nucleus) and when an emission occurs cannot be predicted.
147
Ionisation
The ability to eject electrons from atoms to form ions.
148
Ionising Radiation
Radiation with high energies that can knock off electrons from atoms to form ions.
149
Background Radiation
Nuclear radiation in an environment where no radioactive source has been deliberately introduced.
150
Half-life of a Radioactive Nuclide
Time taken for half the nuclei of that nuclide in any sample to decay.
151
Nuclear Fission
A process in which the nucleus of an atom splits and releases a huge amount of energy.
152
Nuclear Fusion
A process in which two light atomic nuclei combine to form one heavier atomic nucleus and releases a huge amount of energy.
153
Terminal Velocity
Constant velocity that is achieved when the air resistance is equivalent to the weight of the object, resulting in no resultant force.
154
Pascal’s Principle or Pascal’s Law
If a pressure is applied to an enclosed liquid, the pressure is transmitted to all other parts of the liquid undiminished.
155
Thermal Equilibrium
Describes a state in which two or more objects have the same temperature and that there is no net transfer of energy between them.
156
Echolocation
Location of objects using reflected sound.
157
Earthing
The process of providing a path for electrons to flow from Earth to a positively charged conductor or for excess electrons to flow from a negatively charged conductor to the Earth
158
Conventional Current
the direction of flow of positive charges from the positively charged terminal to the negatively charged terminal of a power source
159
Electron Flow
the direction of flow of electrons from the negatively charged terminal to the positively charged terminal of a power source
160
Short Circuit
occurs when a closed circuit has an alternative path of negligible resistance for current to flow, bypassing the intended path
161
Open Circuit
occurs when there is a break in the circuit, causing no current flow
162
Fleming’s Left Hand Rule
in a current-carrying conductor, the thumb points in the direction of the force, the index finger points in the direction of the magnetic field and the middle finger points in the direction of the current
163
Fleming’s Right Hand Rule
in an a.c. generator, the thumb points in the direction of the motion, the index finger points in the direction of the magnetic field and the middle finger points in the direction of the induced current
Sciences Memory Work
flashcards
Decks in class (5)
# Cards
