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Physics definitions > Definitions of everything > Flashcards

Definitions of everything Flashcards

Includes most (not all) definitions in boxes.

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1
Q

random error vs systematic error

A

random error: when the measured readings are scattered about the true reading with no fixed pattern

systematic error: when the measured readings are consistently larger or consistently smaller than the true reading

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2
Q

accuracy vs precision

A

accuracy: how close the measured reading is to the true value

precision of a set of readings (diff from precision of instrument): how close the measured readings are to each other

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3
Q

Newton’s Third Law of Motion

A

when body A exerts a force on body B, body B exerts on body A a force of the same type that is equal in magnitude and opposite in direction.

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4
Q

Newton’s First Law of Motion

A

an object continues at rest or with constant velocity unless acted upon by a resultant force

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5
Q

The mass of a body

A

property of a body which resists change in motion

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6
Q

The weight of a body

A

force acting on the body due to a gravitational field

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7
Q

Newton’s Second Law of Motion

A

rate of change of momentum of a body is

[magnitude] directly proportional to the resultant force acting on it and

[direction] in the direction of the resultant force

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8
Q

The Principle of Conservation of Linear Momentum states that the

A

total linear momentum of an isolated system of interacting bodies before and after collision remains constant if no net external force acts on the system

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9
Q

The centre of gravity

A

the single point where the weight of a body may be considered to act

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10
Q

Hooke’s Law states that

A

the change in length of a material is directly proportional to the force applied on it when the limit of proportionality is not exceeded.

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11
Q

Upthrust is

A

equal in magnitude and opposite in direction to the weight of fluid displaced by submerged or floating object

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12
Q

Explain the origin of upthrust

A

pressure exerted by water increases with depth

pressure on bottom surface area of cylinder
greater than pressure on top surface area of cylinder

upwards force on bottom surface larger
than downwards force on top surface

net upwards force is upthrust

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13
Q

Principle of moments

A

For a body in rotational equilibrium, sum of clockwise moments about any point is equal to sum of anti-clockwise moments about the same point

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14
Q

a body is in rotational equilibrium when there is:

a body is in translational equilibrium when there is:

a body is in equilibrium when:

A

body is in translational equilibrium when there is
[magnitude] no resultant force
[direction] in any direction

a body is in rotational equilibrium
when there is
[magnitude] no resultant torque
[direction] about any point

a body is in equilibrium when
there is no resultant force in any direction and
there is no resultant torque about any point

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15
Q

work done by a force is

A

the product of the force and the displacement in the direction of the force

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16
Q

one radian is the

A

angle subtended at the centre of a circle by an arc length that is equal to the radius

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17
Q

angular velocity ω (NOT THE SAME AS ANGULAR FREQUENCY IN OSCILLATIONS) is

A

the rate of angular displacement swept out by radius

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18
Q

a gravitational field is

A

a region of space where a mass experiences a gravitational force

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19
Q

Newton’s law of gravitation states that the

A

[type of force] gravitational force of attraction between two point masses

[magnitude] is directly proportional to the product of the masses and

inversely proportional to the square of separation between the masses

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20
Q

Advantage of geostationary satellites? What are they used for?

A

Geostationary satellites allow transmission of signals between two regions at all times because the satellite will remain within “line-of-sight” of ground-based transmission and reception equipment.

They are useful for constant monitoring of weather especially in the equatorial region.

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21
Q

a geostationary satellite must:

A

have a period of 24 hour

be in circular orbit at a particular radius

orbit directly above Equator

move from west to east along same orbital axis as Earth’s rotation

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22
Q

gravitational field strength g at a point in the field is the

A

[type of force] gravitational force of attraction

[ratio] per unit mass

[specifics] by a small test mass
placed at that point

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23
Q

gravitational potential φ at a point in the field is the

A

[process] work done

[ratio] per unit mass

[specifics] in bringing a small test mass
from infinity to that point

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24
Q

an oscillation is

A

a complete to-and-fro motion between two limits

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25
Q

free oscillations are

A

oscillations with constant amplitude without energy loss or gain as there is no external force acting on the system

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26
Q

natural frequency is

A

the frequency at which a system vibratesin the absence of net external forces

27
Q

simple harmonic motion is

A

a type of oscillatory motion

where the acceleration is:

[magnitude] directly proportional to displacement from the equilibrium position

and

[direction] directed opposite to displacement

28
Q

damped oscillations are

A

oscillations where the amplitude decreases exponentially with time because of continuous loss of energy to surroundings due to negative work done against resistive forces so the total energy in the system decreases with time

29
Q

critical damping

A

no oscillations occur, displacement is brought to zero in shortest possible time

30
Q

forced oscillations are

A

oscillations where there is continuous input of energy by external periodic force that maintains the oscillation amplitude

31
Q

resonance is

A

when the driving frequency of external periodic force equals to natural frequency of the system, and the resulting amplitude is maximum because there is maximum rate of transfer of energy from the external driver to the oscillating system

32
Q

progressive waves

A

waves where energy is propagated from one place to another in the direction of wave travel without bulk movement of medium

33
Q

phase φ

A

an angular measure (in either degrees or radians) of the fraction of a cycle completed by the oscillating mass

34
Q

phase difference Δφ

A

measure of how much an oscillation is out of step with another oscillation at the same instant in time

35
Q

Transverse Wave vs Longitudinal Wave

A

a transverse wave is one where the oscillations are normal to the direction of energy propagation

a longitudinal wave is one where the oscillations are parallel to the direction of energy propagation

36
Q

the intensity of a wave is

A

rate of energy flow per unit area that is perpendicular to the direction of wave propagation

37
Q

polarised wave

A

the oscillations are along one direction only, in a single plane that is normal to the direction of energy transfer of the wave

38
Q

the Principle of Superposition states that

A

when two or more waves meet and overlap the resultant displacement is the vector sum of the displacement of each individual wave

39
Q

interference is when

A

(principle of superposition) When two or more waves meet and overlap the resultant displacement is the vector sum of the displacement of each individual wave,

giving rise to a pattern of maximas and minimas

40
Q

diffraction is the

A

spreading of a wave into geometric shadow when it passes through a slit or past an edge of an obstacle

41
Q

What is the SAO framework?

A

check ur notes .-.

42
Q

the Rayleigh Criterion states that

A

the limit for which 2 sources of light can be just distinguished is when the first minima of the diffraction pattern of one source coincides with the central maxima of the diffraction pattern of the other source

43
Q

coherent waves

A

if two waves are coherent, there is constant phase difference between the waves

44
Q

a stationary wave is formed when

A

two waves of the same type, same frequency, wavelength and speed, travelling in opposite directions towards each other, meet and overlap.

45
Q

When asked to explain the formation of stationary waves

A 
describe:
• how 2 progressive waves of the same type
are generated such that they are the
same frequency, wavelength and speed
• how the 2 waves are travelling in
opposite directions towards each other
• where the 2 waves meet and overlap
46
Q

fundamental mode / fundamental frequency

A

the mode of oscillation that has the lowest possible frequency of the standing wave

47
Q

torque of a couple is the

A

product of one of a pair forces and the perpendicular distance between the forces

48
Q

Angular frequency ω (NOT THE SAME AS ANGULAR VELOCITY IN CIRCUILAR MOTION)

A

rate of change of phase of oscillating mass

49
Q

Electric current is the

A

rate of flow of charge

50
Q

electromotive force (e.m.f.) is

A

energy transformed from chemical to electrical per unit charge that is driven around a complete circuit

51
Q

potential difference (p.d.) is

A

energy transformed from electrical to other forms per unit charge that is passing through the component

52
Q

resistance is the

A

ratio of potential difference across component to current passing through it

53
Q

a magnetic field is

A

a region of space in which a permanent magnet, a current-carrying conductor or a moving charge may experience a force

54
Q

magnetic flux density B is

A

force per unit current per unit length of wire carrying a current is that normal to the magnetic field

55
Q

Why magnetic force does no work

A

magnetic force always directed perpendicular to velocity of charged particle

no displacement in the direction of magnetic force so no work done

56
Q

an electric field is

A

a region of space where a stationary charge

experiences an electric force

57
Q

electric field strength E at a point in the field is

A

[type of force] electric force
[ratio] per unit positive charge
[specifics] on a small stationary test charge at that point

58
Q

Coulomb’s Law states that the

A

[type of force ] electric force between two point charges is

[magnitude] directly proportional to product of the two charges and inversely proportional to the square of separation between the two charges

59
Q

Explain why the electric field strength inside a thin conducting sphere is zero.

A

Electric charges in a conductor will move in an electric field.
Charges redistribute until there is zero field strength, so
no resultant force on charges so
no electric field

60
Q

electric potential is the

A

work done per unit positive charge in moving a small test charge from infinity to that point

61
Q

equipotential lines are

A

lines joining points in a field that have the same potential

62
Q

Relationship between Electric Field Strength and Electric Potential

A

[magnitude] electric field strength E is numerically equal to the electric potential gradient at a point in the field

[direction] negative sign shows that the direction of field strength points towards direction of lower potential

63
Q

When a soft iron core is inserted in a solenoid,

A

the core is magnetized
in the same direction as the magnetic flux density set up by the solenoid,
it adds to the magnetic flux density and strengthens the net magnetic field

Physics definitions (1 decks)

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