Definitons For Paper 1 Flashcards

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1
Q

Acceleration

A

The rate of change of velocity

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2
Q

Acceleration of free fall

A

The rate of change of velocity of an object falling in a gravitational field

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3
Q

Air resistance

A

The drag or resistive force experienced by objects moving through air

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4
Q

Antiparallel

A

In the same line but opposite directions

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5
Q

Archimedes’ principle

A

The upthrust of an object in a fluid is equal to the weight of fluid it displaces

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6
Q

Average speed

A

The rate of change in distance calculated over a complete journey

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7
Q

Average velocity

A

Th changes in displacement for a journey divided by the time taken

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8
Q

Braking distance

A

Distance travelled by a vehicle from the time the brakes are applied until the vehicle stops

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9
Q

Breaking strength

A

The stress value at the point of fracture, calculated by dividing the breaking force by the cross-sectional area

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10
Q

Brittle

A

Property of a material that does not show plastic deformation and deforms very little under high stress

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11
Q

Centre of gravity

A

An imaginary point at which the entire weight of an object appears to act

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12
Q

Centre of mass

A

A point through which any externally applied force produces straight-line motion but no rotation

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13
Q

Closed system

A

An isolated system that has no interaction with its surroundings

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14
Q

Component

A

One of the two perpendicular vectors obtained by resolving a vector

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15
Q

Compression

A

The decrease in length of an object when a compressive force is exerted on it

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16
Q

Compressive deformation

A

A change in shape of an object due to compressive forces

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17
Q

Constant speed

A

Motion in which the distance travelled per unit time stays the same

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18
Q

Constant velocity

A

Motion in which the change in displacement per unit time stays the same e

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19
Q

Couple

A

A pair of equal and opposite forces acting on a body but not in the same straight line

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20
Q

Density

A

The mass per unit volume of a substance

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21
Q

Displacement

A

The distance travelled in a particular direction

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22
Q

Drag force

A

The resistive fore exerted by a fluid in an object moving through it

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23
Q

Ductile

A

Property of a material that has a large plastic region in a stress-strain graph

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24
Q

Efficiency

A

The ratio of useful output energy to total input energy

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25
Q

Elastic deformation

A

A reversible change in the shape of an object due to a compressive or tensile force - removal of stress of force will return the object to its original shape and size

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26
Q

Elastic limit

A

The value of stress and force beyond which elastic deformation becomes plastic deformation, and the material or object will no longer return to its original shape and size when the stress or force is removed

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27
Q

Elastic potential energy

A

The energy stored in an object because of its deformation

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28
Q

Energy

A

The capacity for doing work measured in joules

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29
Q

Equilibrium

A

When the net force and net moment acting on a body is zero

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30
Q

Extension

A

The increase in length of an object when a tensile force is exerted on it

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31
Q

Fluid

A

A substance that can flow, including liquids and gases

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32
Q

Force

A

A push or pull on an object measured in newtons

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33
Q

Force constant

A

A quantity determined by dividing force by extension for an object obeying Hookes’ law - constant of proportionality k

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34
Q

Force-extension graph

A

Graph of force against extension with the area under the graph equal to the work done on the material

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35
Q

Force-time graph

A

A graph of net force against time, area under the graph equal to the impulse

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36
Q

Free fall

A

The motion of an object accelerating under gravity with no other force acting on it

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37
Q

Gravitational potential energy

A

The capacity for doing work as a result of an object’s position in a gravatational field

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38
Q

Hooke’s law

A

The force applied is directly proportional to the extension of the spring unless the limit of proportionality is exceeded

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39
Q

Hysteresis loop

A

A loop-shaped plot obtained when loading and unloading a material produce different deformations

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40
Q

Impulse

A

The area under a force-time graph - the product of force and time for which the force acts

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41
Q

Inelastic collision

A

A collision in which kinetic energy is lost

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42
Q

Instantaneous speed

A

The speed at the moment it is measured

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43
Q

Kinetic energy

A

The energy associated with an object as a result of its motion

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44
Q

Limit of proportionality

A

The value of stress or force beyond which stress is no longer directly proportional to strain

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45
Q

Linear momentum

A

A property of an object travelling in a straight line - product of its mass and velocity

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46
Q

Mass

A

Amount of matter - base quantity is kilograms

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47
Q

Moment

A

The product of force and perpendicular distance from a pivot

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48
Q

Newtons first law of notion

A

A body will remain at rest or continue to move with constant velocity unless acted upon by a resultant force

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49
Q

Newton’s second law of motion

A

The rate of change in momentum of an object is directly proportional to the resultant force and takes place in the direction of the force

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50
Q

Newton’s third law of motion

A

When two objects interact, each exerts an equal but opposite force on the other during the interaction

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51
Q

Normal contact force

A

The force exerted by a surface on an object which acts perpendicularly to the surface

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52
Q

Perfectly elastic collision

A

A collision in which no kinetic energy is lost

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53
Q

Plastic deformation

A

An irreversible change in the shape of an object sue to a compressive or tensile force - removal of stress or force produces permanent deformation

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54
Q

Plumb-line

A

A string with a weight used to provide a vertical reference line

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55
Q

Power

A

The rate of work done measured in watts

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56
Q

Pressure

A

The force exerted per unit cross-sectional area measured in pascals

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57
Q

Principle of conservation of energy

A

The total energy of a system remains constant - energy cannot be created nor can it be destroyed

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58
Q

Principle of moments

A

For a body in rotational equilibrium the sum of anticlockwise moments about a point is equal to the sum of clockwise moments about the same point

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59
Q

Projectile

A

An object that us throw or propelled on the surface of the earth

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60
Q

Restoring force

A

A force that tries to return a system to its equilibrium position

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61
Q

Resultant vector

A

A single vector that has the same effect as two or more vectors added together

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62
Q

Scalar quantity

A

A quantity with magnitude but no direction

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63
Q

Stiffness

A

The ability of an object to resist deformation

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64
Q

Stopping distance

A

The total distance travelled from the time when a driver first sees a reason to stop to the time when the vehicle stops the sum of thinking and braking distances

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65
Q

Strong material

A

Large value for ultimate tensile strength

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66
Q

Tensile deformtaion

A

A change in the shape of an object due to tensile forces

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67
Q

Tensile force

A

Equal and opposite forces acting on a material to stretch it

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68
Q

Tensile strain

A

The extension per unit length

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69
Q

Tensile stress

A

The force per unit cross-sectional area

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70
Q

Tension

A

The pulling force exerted by a string, cable or chain on an object

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71
Q

Terminal velocity

A

The constant speed reached by an object when the drag force is equal and opposite to the weight of the object

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72
Q

Thinking distance

A

The distance travelled by a vehicle from when the driver first perceives a need to stop to when the brakes are applied

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73
Q

Time of flight

A

Time taken for an object to complete its motion

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74
Q

Torque of a couple

A

The product of one of the force of a couple and the perpendicular distance between the forces

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75
Q

Ultimate tensile strength

A

The maximum stress that a material can withstand before it breaks

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76
Q

Uniform gravitational field

A

A gravitational field in which the field lines are parallel and the value for g remains constant

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77
Q

Upthrust

A

The upward buoyant force exerted on a body immersed in a fluid

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78
Q

Velocity

A

A vector quantity equal to the rate of change in displacement

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79
Q

Weight

A

The gravitational force on an object measured in newtons

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80
Q

Work

A

The product of force and the distance moved in the direction of the force measured in joules

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81
Q

Yield point

A

A point on a stress-strain graph beyond which the deformation is no longer entirely elastic

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82
Q

Absolute scale of temperature

A

A scale for measuring temperature based on absolute zero and the triple point of pure water - increments are equal to those of the Celsius scale = Kelvin scale

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83
Q

Absolute zero

A

The lowest possible temperature, the temperature at which substances have minimum internal energy

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84
Q

Amount of substance

A

A measure of the amount of matter in moles

85
Q

Angular frequency

A

A quantity used in oscillatory motion - equal to the product of frequency and 2π

86
Q

Angular velocity

A

The rate of change of angle for an object moving in a circular path

87
Q

Aphelion

A

The furthest point from the sun in an orbit

88
Q

Arcminute

A

A minute of arc 1degrees = 60 arcminutes

89
Q

Arcsecond

A

A second of arc 1 arcminute = 60 arcseconds

90
Q

Astronomical unit

A

The mean distance from the earth to the sun = 1.5x10^11m

91
Q

Avogadro constant

A

The number of atoms in 0.012kg (12g) of carbon-12 = Na

92
Q

Big bang

A

The theory that at a moment in the bast all the matter in the universe was contained in a single point the beginning of space and time that expanded rapidly outwards

93
Q

Black body

A

An idealised object that absorbs all the em radiation incident on it and when in thermal equilibrium emits a characteristic distribution of wavelengths at a specific temperature

94
Q

Black hole

A

The remnant core of a massive star after it has gone supernova and the core has collapsed so far that in order to escape it an object would need an escape velocity greater than the speed of light therefore nothing can escape

95
Q

Blue shift

A

The shortening of observed wavelength that occurs when a wave source is moving towards the observer - if a galaxy is moving towards the earth, the absorption lines in its spectrum, will be blue-shifted moved towards the blue end of the spectrum

96
Q

Boltzmann constant

A

The molar gas constant R divided by the avogadro constant Na, a constant that relates the mean kinetic merge of the atoms or molecules in a gas to the gas temperature - k

97
Q

Boyle’s law

A

The pressure of an ideal gas is inversely proportional to its volume - provided that the mass of gas and the temperature do not vary

98
Q

Brownian motion

A

The continuous random motion of small particles suspended in a fluid, visible under a mircoscope

99
Q

Celsius scale

A

A temperature scale with 100 degrees between the freezing point and the boiling point of pure water

100
Q

Centripetal acceleration

A

The acceleration of any object travelling in a circular path at constant speed, which always acts towards the centre of the circle

101
Q

Centripetal force

A

A force that keeps a body moving with a constant speed in a circular path

102
Q

Chandrasekhar limit

A

The mass of a star’s core beneath which the electron degeneracy pressure us sufficient to prevent gravitational collapse

103
Q

Comet

A

A small irregular body made of ice, dust and small pieces of rock in an orbit around the sun

104
Q

Conical pendulum

A

A simple pendulum that instead of swinging back and forth rotates in a horizontal circle at constant speed

105
Q

Continuous spectrum

A

A spectrum in which all visible frequencies or wavelengths are present

106
Q

Cosmological principle

A

The assumption that, when viewed on a large enough scale, the universe is homogenous and isotopic and laws of physics are universal

107
Q

Damping

A

An oscillation is damped when an external force that acts on the oscillator has the effect of reducing the amplitude of its oscillations

108
Q

Dark energy

A

A hypothetical form of energy that fills all of space and would explain the accelerating expansion of the universe

109
Q

Dark matter

A

A hypothetical form of matter spread throughout the galaxy that neither emits nor absorbs light - it could explain the differences between the predicted and observed velocities of stars in galaxies

110
Q

Doppler effect

A

The change in frequency and wavelength of waves received from an object moving relative to an observer compared with what would be observed without relative motion

111
Q

Driving frequency

A

The frequency with which the periodic driver force is applied to a system in forced oscillation

112
Q

Eccentricity

A

A measure of elongation of an ellipse

113
Q

Ellipse

A

An elongated circle with two foci

114
Q

Electron degeneracy pressure

A

A quantum-mechanical pressure created by the electrons in the core of a collapsing star due to the Pauli exclusion principle

115
Q

Emission line spectrum

A

A set of specific frequencies of em radiation, visible as bright lines in spectroscopy, emitted by excited atoms as their electrons make transitions between higher and lower energy states, losing the corresponding amount of energy in the form of photons

116
Q

Energy level

A

A discrete amount of energy that an electron within an atoms is permitted to process

117
Q

Equation of state of an ideal gas

A

PV=nRT where n is the number of moles of gas

118
Q

Escape velocity

A

The minimum velocity at which an object has just enough energy to leave a specified gravitational field

119
Q

Excited

A

An atom containing an electron or electrons that have absorbed energy and been boosted into a higher energy level

120
Q

Expanding universe

A

The idea that the fabric of space and time is expanding in all directions and that as a result any point = is moving away from every other point in the universe and the further away the points are apart the faster their relative motion away from each other

121
Q

Forced oscillation

A

An oscillation in which a periodic driver force is applied to an oscillator

122
Q

Free oscillation

A

The motion of a mechanical system displaced from its equilibrium position and then allowed to oscillate without an external forces

123
Q

Frequency

A

The number of complete oscillations per unit time

124
Q

Galaxy

A

A collection of stars and interstellar dust and gas bound together by their mutual gravitational force

125
Q

Gas laws

A

The laws governing the behaviour of ideal gases

126
Q

Gas pressure

A

In stars the pressure of the nuclei in the star’s core pushing outwards and counteracting the gravitational force pulling the matter in the star inwards

127
Q

Geostationary satellite

A

A satellite that remains in the same position relative to a spot on the earths surface, by orbiting in the direction of the earth’s rotation over the equator with a period of 24 hours

128
Q

Grating equation

A

An equation that can be used to determine accurately the wavelength of monochromatic light sent through a diffraction grating dsin θ = n λ

129
Q

Grating spacing

A

The separation between adjacent lines or slits in a diffraction grating

130
Q

Gravitational field

A

A field created around any object with mass, extending all the way to infinity, but diminishing as the distance from the centre of mass of the object increases

131
Q

Gravitational field strength

A

The gravitational force exerted per unit mass at a point within a gravitational field

132
Q

Gravitational potential

A

The work done per unit mass to bring an object from infinity to a point in the gravitational field- Jkg^-1

133
Q

Ground state

A

The energy level with the most negative value possible for an electron within an atom - the most stable energy state of an electron

134
Q

Heavy damping

A

Damping that occurs when the damping forces are large and the period of the oscillations increase slightly with the rapid decrease in amplitude

135
Q

Hertzsprung-russel diagram

A

A graph showing the relationship between the luminosity of star in our galaxy and their average surface temperature

136
Q

Homogenous

A

Uniform in terms of the distribution of matter across the universe when viewed on a sufficiently large scale

137
Q

Hubble constant

A

The gradient of best-fit line for a plot of recessional speed against distance from earth of other galaxies

138
Q

Hubbles law

A

The recessional speed of a galaxy is almost directly proportional to its distance from the Earth

139
Q

Ideal gas

A

A model of a gas including assumptions that simplify the behaviour of real gases

140
Q

Inflation

A

A phase of astonishing acceleration of the expansion of the universe thought to have occurred 10^-35s after the big bang

141
Q

Internal energy

A

The sum of the randomly distributed kinetic and potential energies of the atoms, ions and molecules within the substance

142
Q

Isochronous oscillator

A

An oscillator that has the same period regardless of amplitude

143
Q

Isotherm

A

A line on a pressure-volume graph that connects points at the same temperature

144
Q

Isotropic

A

The same in all directions

145
Q

Kelvin

A

SI base unit of the absolute temperature scale

146
Q

Keplers first law

A

The orbit of a planet is an ellipse with the sun at one of the two foci

147
Q

Keplers second law

A

A line segment connecting a planet to the sun sweeps out equal areas during equal intervals of time

148
Q

Keplers third law

A

The square of the orbital period T of a planet is directly proportional to the cube of its average distance r from the sun

149
Q

Kinetic model/Kinetic theory of matter

A

A model that describes all substances as made of atoms , ions or molecules, arranged differently depending on the phase of the substance

150
Q

Light damping

A

Damping that occurs when the damping forces are small and the period of the oscillations is almost unchanged

151
Q

Light-year

A

The distance travelled by light in a vacuum in a time of one year

152
Q

Luminosity

A

The total radiant power output of a star - unit W

153
Q

Main sequence

A

The main period in a stars life, during which it is stable

154
Q

Maxwell-Boltzmann distribution

A

The distribution of the speeds is particles in a gas

155
Q

Mean square speed

A

The mean of the squared velocities of all the particles in a gas

156
Q

Microwave background radiation

A

The microwave signal of uniform intensity detected from all directions of the sky, which fits the profile for a black body at a temperature of 2.7K

157
Q

Molar gas constant

A

The constant in the equation of state of an ideal as - R

158
Q

Molar mass

A

The mass of one mole of a substance

159
Q

Mole

A

The amount of substance that contains as many elementary entities as there are atoms in 12g of carbon-12

160
Q

Natural frequency

A

The frequency of a free oscillation

161
Q

Nebula

A

A cloud of dust and gas often many hundreds of times larger than our solar system

162
Q

Neuton star

A

The remnant core of a massive star after the star has gone supernova (if the mass of the core is greater than Chandrasekhar limit) the core has collapsed under gravity to an extremely high density as it is almost entirely made up of neutrons

163
Q

Newtons law of gravitation

A

The force between two point masses is directly proportional to the product of the masses and inversely proportional to the square of the separation between them

164
Q

Oscillating motion

A

Repetitive motion of an object around its equilibrium position

165
Q

Parallax angle

A

The angle of the apparent shift in the position of a relatively close star against the backdrop of much more distant stars as the earth makes a quarter an orbit around the sun

166
Q

Parsec

A

The distance at which a radius of one AU subtends an angle of one arcsecond

167
Q

Perihelion

A

The closest point to the sun in an orbit

168
Q

Period

A

The time taken to complete one oscillation

169
Q

Phase

A

A phase of matter is its state (sold, liquid or gas)

170
Q

Phase difference

A

The difference in displacement between two oscillating objects or the displacement of an oscillating object at different times

171
Q

Planet

A

An object in orbit around a star with a mass large enough for its own gravity to give it a round shape, that undergoes no fusion reactions and that has cleared its orbit of most other objects

172
Q

Planetary nebula

A

The outer layers of a red giant that gave drifted off into space, leaving the hot core behind at the centre as a white dwarf

173
Q

Planetary satellite

A

A body in orbit around a planet - it may be natural or artificial

174
Q

Protostar

A

A very hot, very dense sphere of condensing dust and gas that is on the way to becoming a star

175
Q

Radiation pressure

A

Pressure from the photons in the core of a star which acts outwards to counteract the pressure from the gravitational force pulling the matter in the star inwards

176
Q

Red giant

A

An expanding star at the end of its life, with an inert core in which fusion no inter takes place, but in which fusion of lighter elements continues in the shell around the core

177
Q

Red shift

A

The lengthening of observed wavelength that occurs when a wave source is moving away from the observer - if a galaxy is moving away from the earth the absorption lines in its spectrum will be red-shifted

178
Q

Red supergiant

A

A huge star in the last stages of its life before it explodes in a supernova

179
Q

Resonance

A

The increase in amplitude of a forced oscillation when the driving frequency matches the natural frequency of the oscillating system

180
Q

Root mean square speed

A

The square root of the mean square speed of all particles in a gas

181
Q

Satellite

A

A body orbiting around the planet

182
Q

Simple harmonic motion

A

Oscillating motion for which the acceleration of the object is directly proportional to its displacement and is directly towards some fixed point

183
Q

Solar system

A

A planetary system consisting of a star and at least one planet in orbit around it

184
Q

Specific heat capacity

A

The energy required per unit mass to change the temperature by 1K

185
Q

Specific latent heat

A

The energy required to change phase per unit mass while at constant temperature

186
Q

Specific latent heat of fusion

A

The energy required to change unit mass of a substance from solid to liquid while at constant temperature

187
Q

Specific latent heat of vaporisation

A

The energy required to change unit mass of a substance from liquid to gas while at constant temperature

188
Q

Spectral line

A

A line in an emission line spectrum or absorption line spectrum at a specific wavelength

189
Q

Spectroscopy

A

A technique in which spectral lines are identified and measured in order to identify elements present within stars

190
Q

Stefan constant

A

The constant in Stefan’s law relating the luminosity of a star to its surface area and its absolute surface temperature

191
Q

Stellar parallax

A

A technique used to determine the distance to stars that are relatively close to the earth by comparing their apparent positions against distant stars at times 6 months apart

192
Q

Supernova

A

The implosion of a red supergiant at the end of its life which leads to subsequent ejection of stellar matter into space leaving an inert remnant core

193
Q

Thermal equilibrium

A

A state in which there is no net flow of thermal energy between the objects involved - they must be at they same temperature

194
Q

Triple point

A

For a given substance one specific temperature and rescue at which all three phases of the substance can exist in thermodynamic equilibrium

195
Q

Uniform gravitational field

A

A gravitational field in which the field lines are parallel and the value for g remains constant

196
Q

Universe

A

Everything that exists within space and time e

197
Q

Warns displacement law

A

The peak wavelength at which the intensity of radiation from a black body is a maximum is inversely proportional to the absolute temperature of the black body

198
Q

Absorption line spectrum

A

A set of specific frequencies of electromagnetic radiation visible as dark lines in an otherwise continuous spectrum on spectroscopy they are absorbed by atoms as their electrons are excited between energy states by absorbing the corresponding amount of energy in the form of photons every element has a characteristic line spectrum

199
Q

Fiducial marker

A

A marker for a point used as a fixed basis for measurement or comparison

200
Q

Gravitational field

A

A field created around any object with mass, extending all the way to infinity but diminishing as the distance from the centre of mass of the object increases

201
Q

Gravatational field strength

A

The gravitational force exerted over unit mass at a point within a gravitational field

202
Q

Gravatational potential

A

The work done per unit mass to bring an object from infinity to a point in the gravitational field

203
Q

Negative temperature coefficient

A

A relationship in which a variable decreases as temperature increases - resistance of ntc thermistors

204
Q

Neutron star

A

The remnant core of a massive star after the star has gone supernova and the core has collapsed under gravity to an extremely high density as it is made up of neutrons

205
Q

Principle of conservation of momentum

A

Total momentum of a system remains the same before and after a collision

206
Q

White dwarf

A

A very dense star formed from the core of a red giant in which no fusion occurs

207
Q

Wien’s displacement law

A

The peak wavelength at which the intensity of radiation from a black body is a maximum is inversely proportional to the absolute temperature T of the black body

208
Q

Young’s modulus

A

The ratio of tensile stress to tensile strain when these quantities are directly proportional to each other