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A-level Physics > Definitions and laws > Flashcards

Definitions and laws Flashcards

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1
Q

What is braking distance?

A

The distance travelled between the brakes being applied and the vehicle coming to a stop. It is affected by the vehicle and road conditions.

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2
Q

What is displacement?

A

The direct distance between an object’s starting and ending positions. It is a vector quantity and so has both a direction and a magnitude.

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3
Q

What is stopping distance?

A

The sum of thinking distance and braking distance for a driven vehicle.

Stopping distance is crucial for safe driving and varies with speed and road conditions.

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4
Q

Define thinking distance.

A

The distance travelled in the time it takes for the driver to react.

Like reaction time, thinking distance is also affected by alcohol, drugs, and tiredness.

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5
Q

What is Archimedes’ Principle?

A

The upwards force acting on an object submerged in a fluid is equal to the weight of the fluid it displaces.

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6
Q

Define Centre of Gravity.

A

The single point through which the object’s weight can be said to act.

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7
Q

Define Centre of Mass.

A

The single point through which all the mass of an object can be said to act.

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8
Q

What is a Couple in physics?

A

Two equal and opposite parallel forces that act on an object through different lines of action.

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9
Q

What is Drag?

A

The frictional force that an object experiences when moving through a fluid.

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10
Q

What conditions must be met for an object to be in Equilibrium?

A

Both the resultant force and resultant moment acting on the object must be equal to zero.

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11
Q

Define Moment of Force.

A

The product of a force and the perpendicular distance from the line of action of the force to the pivot.

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12
Q

State Newton’s Second Law.

A

The sum of the forces acting on an object is equal to the rate of change of momentum of the object.

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13
Q

What is Normal Contact Force?

A

The reaction force between an object and surface.

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14
Q

What is the Principle of Moments?

A

For an object to be in equilibrium, the sum of the clockwise moments acting about a point must be equal to the sum of the anticlockwise moments acting about the point.

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15
Q

What is Tension?

A

The result of two forces acting on an object in opposite, outwards directions.

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16
Q

Define Terminal Velocity.

A

The maximum velocity of an object that occurs when the resistive and driving forces acting on the object are equal to each other.

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17
Q

What is Upthrust?

A

The upwards force that a fluid applies on an object.

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18
Q

What does the Conservation of Energy state?

A

In a closed system with no external forces, the total energy before an event equals the total energy after the event.

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19
Q

What is Gravitational Potential Energy?

A

The energy gained by an object when it is raised by a height in a gravitational field.

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20
Q

What characterizes a Brittle object?

A

Shows very little strain before reaching its breaking stress.

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21
Q

What is Compression?

A

The result of two coplanar forces acting into an object.

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22
Q

Define Compressive Deformation.

A

The changing of an object’s shape due to compressive forces.

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23
Q

What does Ductile mean?

A

A material that can undergo very large extensions without failure.

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24
Q

What is Elastic Deformation?

A

When a material returns to its original shape after the deforming forces are removed.

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25
What is Elastic Potential Energy?
The energy stored in an object when it is stretched.
26
State Hooke's Law.
The extension of an elastic object is directly proportional to the force applied to it up to the object's limit of proportionality.
27
What is Plastic Deformation?
When a material does not return to its original shape after the deforming forces are removed.
28
What is a Polymeric material?
A material made from polymers.
29
Define Spring Constant.
The constant of proportionality for the extension of a spring under a force.
30
What is Tensile Deformation?
The changing of an object's shape due to tensile forces.
31
Define Ultimate Tensile Strength.
The maximum stress an object can withstand before fracture occurs.
32
What does Conservation of Momentum state?
The total momentum of a system before an event must equal the total momentum after the event.
33
Define Elastic Collisions.
A collision in which the total kinetic energy before the collision equals the total kinetic energy after the collision.
34
What is Impulse?
The change of momentum of an object when a force acts on it.
35
Define Inelastic Collisions.
A collision where the total kinetic energy before the collision is not equal to the total kinetic energy after the collision.
36
What is Linear Momentum?
The product of an object's mass and linear velocity.
37
State Newton's First Law.
An object will remain in its current state of motion unless acted on by a resultant force.
38
What does Newton's Second Law state?
The sum of the forces acting on an object is equal to the rate of change of momentum of the object.
39
State Newton's Third Law.
Every action has an equal and opposite reaction.
40
What is Absolute Uncertainties?
The interval that a value is said to lie within, with a given level of confidence. ## Footnote Absolute uncertainties help quantify the reliability of measurements.
41
Define Accuracy in the context of measurements.
A measure of how close a measurement is to the true value. ## Footnote Accuracy is crucial for validating experimental results.
42
What are Dependent Variables?
The variable being measured in an experiment, dependent on the independent variable. Plotted on the y-axis of a graph. ## Footnote Understanding dependent variables is essential for analyzing experimental outcomes.
43
What are Independent Variables?
The variable that is changed by the experimenter in an experiment, plotted on the x-axis of a graph. ## Footnote Independent variables are manipulated to observe their effect on dependent variables.
44
Define Precision.
A measure of how close a measurement is to the mean value, indicating the magnitude of random errors. ## Footnote Precision does not reflect accuracy, as data can be precise but not accurate.
45
What are Random Errors?
Unpredictable variation between measurements leading to a spread of values about the true value. ## Footnote Random errors can be minimized through repeated measurements.
46
What are SI Units?
The standard units used in equations: candela, metres, kilograms, seconds, amps, Kelvin, and moles. ## Footnote SI units provide a universal language for scientific measurement.
47
What are Systematic Errors?
Causes all readings to differ from the true value by a fixed amount and cannot be corrected by repeat readings. ## Footnote Systematic errors require a change in technique or apparatus to resolve.
48
What are Zero Errors?
A form of systematic error caused when a measuring instrument doesn't read zero at a value of zero, resulting in all measurements being offset by a fixed amount. ## Footnote Identifying zero errors is crucial for accurate measurements.
49
Gravitational Field Strength
The force per unit mass exerted on a small test mass placed within the field.
50
Gravitational Field:
A region surrounding a mass in which any other object with mass will experience an attractive force.
51
Gravitational Potential Energy:
The component of an object's energy due to its position in a gravitational field.
52
Gravitational Potential:
The work done per unit mass required to move a small test mass from infinity to that point.
53
Kepler's First Law:
All planets travel in elliptical orbits, centred around the sun.
54
Kepler's Second Law:
All planets sweep out the same area in a given period of time.
55
Kepler's Third Law:
The square of a planet's period is directly proportional to the cube of its mean distance to the sun.
56
Newton's Law of Gravitation:
The force between two masses is proportional to the product of the masses involved and inversely proportional to the square of the separation of the masses.
57
Absorption Line Spectrum:
A spectrum consisting of dark lines at specific frequencies that have been absorbed by the gases present. Elements can only absorb certain energies, and therefore frequencies, of photons.
58
Astronomical Unit:
The mean distance of the earth to the sun.
59
Big Bang Theory:
The theory that the universe originated as a small, dense and hot region that expanded and cooled forming the structures in the universe we see today.
60
Stefan's law
A law stating that the power output (luminosity) of a star is directly proportional to its surface area and its absolute temperature to the 4* power.
61
Chandrasekhar Limit:
The maximum mass that a white dwarf star can have whilst remaining stable. (1.44 solar masses)
62
Comets:
Concentrated clusters of ice and dust that travel through space. When near the sun, they begin to melt and so leave a trail as they move.
63
Continuous Spectrum:
A spectrum that covers a full range of frequencies without any gaps. The electromagnetic spectrum is an example of a continuous spectrum.
64
Cosmological Principle:
A principle stating that the universe is isotropic (same in all directions to all observers) and homogenous (matter is distributed evenly).
65
Dark Energy:
An energy that is responsible for the acceleration in the expansion of the universe which cannot be explained by any observable energy.
66
Doppler Effect:
The apparent change in the wavelength of a wave as the source moves relative to an observer. For a source moving away the wavelength increases, for a source moving towards the observer the wavelength decreases.
67
Electron Degeneracy Pressure:
The outwards force, resisting the inwards force of gravity, produced as a result of multiple electrons not being able to exist in identical states in an energy level.
68
Emission Line Spectrum:
A series of bright lines at specific frequencies that have been emitted by the gases present. Elements can only release photons of certain energies, and therefore frequencies.
69
Galaxies:
Collections of billions of stars, planets, gases and dust, held together by gravitational attraction.
70
Hertzsprung-Russell Diagram:
A visual representation of the lifecycle of a star. It is a plot of luminosity against temperature.
71
Hubble's Law:
The speed of a galaxy moving away from ours is proportional to its distance away from us. The constant of proportionality is Hubble's constant.
72
Light-Year:
The distance travelled through space by a photon in a year.
73
Nebula:
A cloud of dust and gas in space.
74
Neutron Star:
An incredibly dense star that is formed when the core of a large star collapses. Protons and electrons are forced together under gravity to form neutrons.
75
Parsec:
The distance at which the angle of parallax is 1 arcsecond.
76
Planet:
A body that orbits around a star, in our case, the Sun.
77
Planetary Satellites:
Bodies that orbit a planet. The gravitational force of the planet's mass provides the centripetal force of rotation.
78
Red-Giant:
A stage in the life cycle of a star less than 3 solar masses, in which the hydrogen has run out and the temperature of the star increases. Helium nuclei fuse to form heavier elements.
79
Solar Systems:
A collection of planets that orbit a common star.
80
Stellar Parallax:
The change in position of an object depending on the viewing angle. It can be used to estimate the distance of a star, based on how much it moves relative to the background of stars in the time it takes for the earth to move half an orbit.
81
Supernova:
When a star greater than 1.4 solar masses dies, the core collapses rapidly inward and becomes rigid. The outer layers then fall inward and rebound off of the core in a shockwave, causing heavy elements to be fused and distributed into space in an explosion.
82
Universe:
The name given to all space and matter.
83
White Dwarf:
A dense star, similar mass to the sun, similar size to the earth. A final stage of a low mass star's life with low luminosity.
84
Wien's Displacement Law:
A law stating that the peak wavelength of emitted radiation is inversely proportional to its absolute temperature.
85
Black hole:
a region of space having a gravitational field so intense that no matter or radiation can escape.
86
Black body
a hypothetical perfect absorber and radiator of energy, with no reflecting power.

A-level Physics (13 decks)

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