definitions Flashcards

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1
Q

Systematic errors

A

Result in all readings or measurements being always smaller or larger than the true value by a fixed amount

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2
Q

Random errors

A

Results in readings or measurements being scattered about a mean value. These errors have equal probability of being positive or negative

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3
Q

Accuracy

A

degree of closeness of the mean value of the measurements to the true value
it is affected by systematic error

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4
Q

Precision

A

degree of agreement between repeated measurements of the same quantity
it is affected by random error

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5
Q

Newtons first law

A

every object continues in its state of rest or uniform motion in a straight line unless an external resultant force acts upon it

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6
Q

Newtons second law

A

rate of change of momentum of a body is proportional to the resultant force acting on it and the change occurs in the direction of the force

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7
Q

Newtons third law

A

if body A exerts a force on body B, then body B exerts an equal but opposite force on body A

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8
Q

Principle of conservation of momentum

A

when a system of bodies interact the total momentum of the system remains constant provided no net external force acts on it

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9
Q

Impulse

A

product of the force acting on an object and the time for which the force acts

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10
Q

Momentum

A

product of the mass of an object and its velocity

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11
Q

Hookes law

A

extension of a spring is proportional to the applied force if the limit of proportionality is not exceeded

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12
Q

Centre of gravity

A

point through which the line of action of the entire weight of a body appears to act

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13
Q

Pressure

A

normal force acting per unit area, where the force is acting at right angles to the area

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14
Q

Upthrust

A

vertical upwards force exerted on a body by a fluid when it is fully or partially submerged in the fluid due to the difference in fluid pressure

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15
Q

Principle of floatation

A

For an object floating in equilibrium, the upthrust is equal in magnitude and opposite in direction to the weight of the object

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16
Q

Moment

A

of a force about a point is defined as the product of the force and the perpendicular distance from the point to the line of action of the force

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17
Q

Principle of moments

A

For a body in rotational equilibrium, the sumo f all the clockwise moments about any axis must equal the sum of all the anticlockwise moments about the same axis

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18
Q

Work done

A

by a constant force is the product of the force and the displacement in the direction of the force

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19
Q

Energy

A

the capacity to do work

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20
Q

Law of conservation of energy

A

energy cannot be created or destroyed. it can only be converted from one form to another

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21
Q

Power

A

rate of work done or energy conversion with respect to time

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22
Q

Angular displacement

A

angle an object makes with respect to a reference line

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23
Q

Angular velocity

A

rate of change of its angular displacement wrt time

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24
Q

Period

A

time taken for an object/particle of a wave to make 1 complete revolution/oscillation

25
Q

Frequency

A

number of revolutions/oscillations made per unit time

26
Q

Newtons law of gravitation

A

states that 2 point masses attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

27
Q

Gravitational field

A

region of space in which a mass placed in that region experiences a gravitational force

28
Q

Gravitational field strength

A

at a point in space is defined as the g force experienced per unit mass at that point

29
Q

Gravitational potential energy

A

of a mass at a point in a g field is the work done by an external force in bringing the mass from infinity to that point

30
Q

Escape velocity

A

minimum speed needed for the object to just escape from the g influence of a massive body

31
Q

Gravitational potential

A

at a point in a g field is the work done per unit mass by an external force in bringing a small test mass from infinity to that point

32
Q

Geostationary satellite

A

remains in a fixed position in the sky when viewed from any location on Earths surface

33
Q

Simple Harmonic motion

A

motion of a particle about a fixed point such that its acceleration is proportional to its displacement from the fixed point and is always directed towards the point

34
Q

Angular frequency

A

rate of change of phase angle of the oscillation and is equal to the product of 2pi and its frequency

35
Q

Amplitude

A

magnitude of the max displacement of the particle (in a wave) from its eqm position

36
Q

Free oscillation

A

occurs when an object oscillates with no resistive and driving forces acting on it. its total energy and amplitude remain constant with time

37
Q

Forces oscillations

A

body is subjected to a periodic external driving force and made to oscillate at the frequency of the driving force, which may not be its natural frequency

38
Q

Resonance

A

System responds at max amplitude to an external driving force. this occurs when the freq of the driving force is equal to the natural freq of the driving system

39
Q

Progressive waves

A

transports energy from one point to another in the direction of wave propagation

40
Q

Displacement

A

distance in a specific direction of a particle of a wave from its eqm position

41
Q

Phase angle

A

angle that gives a measure of the fraction of a cycle that has been completed by an oscillating particle or by a wave (e pi is one full oscillation)

42
Q

Phase difference

A

between 2 particles in a wave/between 2 waves at a point is a measure of the fraction of a cycle which one is ahead of the other

43
Q

Wavefront

A

line or surface joining points on a wave that are in phase (wave travels perpendicular to the wavefront)

44
Q

Intensity

A

rate of transfer of energy per unit area normal to the direction of the energy transfer of the wave

45
Q

Transverse wave

A

particles oscillate in a direction perpendicular to the direction of energy transfer

46
Q

Longitudinal waves

A

particles oscillate in a direction parallel to the direction of energy transfer

47
Q

Polarisation

A

oscillations of the wave particles in a transverse wave are restricted to one direction only and this direction is perpendicular to the direction of energy transfer

48
Q

Malus Law

A

intensity of a beam of plane polarised light after passing through a polariser varies with the square of the cosine of the angle through which the polariser is rotated from the position that gives max intensity

49
Q

Superposition

A

when 2 or more waves of the same type meet at a point in space, the resultant displacement at that point is equal to the vector sum of the displacements of the individual waves at that point

50
Q

Stationary waves

A

result of the superposition of 2 progressive waves of the same type, frequency, amplitude and speed, travelling along the same line but in opposite directions

51
Q

Antinode

A

point in a stationary wave where amplitude is the max

52
Q

Node

A

point in a stationary wave where amplitude is 0

53
Q

Diffraction

A

bending of waves after passing through an aperture or round an obstacle

54
Q

Coherence

A

waves are coherent when they have a constant phase difference (same freq)

55
Q

Interference

A

superposition of 2 or more waves to give a resultant wave whose resultant amplitude is given by the principle of superposition

56
Q

Constructive interference

A

when 2 coherent waves arrive at the same point with a phase difference of 0 to produce a maximum

57
Q

Destructive interference

A

when 2 coherent waves arrive at the same point with a phase difference of pi to produce a minimum

58
Q

Path difference

A

diff in the distance that each wave travels from its source to the point where they meet

59
Q

Rayleigh criterion

A

states that 2 images are just resolved by an aperture when the central max of the diffraction pattern of 1 image falls on the 1st minimum of the diffraction pattern of the other image