Equations and constants Flashcards

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1
Q

Specific charge

A

charge (C) /mass (Kg) unit- C/Kg

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2
Q

The energy of a photon

A

Planck constant (J) * frequency (Hz) unit- Js (joule seconds)

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3
Q

work function

A

Planck constant * threshold frequency

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4
Q

photoelectric equation

A
Planck constant * frequency(hz) = 
work function(j) + KE(max)(j)
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5
Q

stopping potential of an electron

A

stopping potential * charge of electron = kinetic energy

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6
Q

the equation for the change in energy between energy levels

A

ΔE=E1-E2=hf (this shows that the change in energy level is exactly equal to the energy of the photon emitted)

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7
Q

de Broglie’s equation for wavelength

A

wavelength= plank constant / momentum

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8
Q

Frequency (using #oscillations)

A

oscillations / time(s)

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9
Q

Frequency (using periods)

A

1 / period(s)

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10
Q

wave speed

A

frequency(Hz)*wavelength (m) speed in m/s

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11
Q

string tension

A

mass held(kg) * gravity(m/s^2) tension-N

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12
Q

mass per unit length of a string

A

mass of string(kg) / length(m)

mass per length in Kg/m

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13
Q

frequency of the first harmonic of a string

A

(1/ (2*length(m))) * (square root (tension(N)/ mass per unit length(Kg/m))) frequency in Hz

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14
Q

spacing between fringes in the double-slit experiment

A

(λ*distance from slits to screen)/space between slits

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15
Q

the pattern of a diffraction grating

A

slit spacing * Sin(angle between the maximum and zero-order line) = λ of incident light * order of the maximum

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16
Q

slit spacing

A

1/x (x= number of slits per meter)

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17
Q

refractive index

A

speed of light in a vacuume / speed of light in the material

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18
Q

Snell’s law

A

starting refractive indexSin(i)=ending refractive indexSin(r)

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19
Q

the equation for the critical angle

A

Sin (the critical angle) =
the refractive index of the less optically dense material
/
the refractive index of the more optically dense material

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20
Q

moment of a force

A

force (N) * perpendicular distance from the turning point to the line of action of the force (m)

moment in Nm

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21
Q

moment of a couple

A

force (N) * perpendicular distance between the lines of action of the two forces (m)

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22
Q

velocity

A

Δdisplacement / Δtime

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23
Q

average speed/velocity

A
total distance (or displacement for velocity)
/ total time
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24
Q

acceleration

A

Δvelocity / Δtime

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25
Q

S, U, V, A, T equations

A

v=u+at
s= ((u+v)/2)
t
s= (ut) + 1/2(at^2)
v^2= u^2 + 2as

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26
Q

verticle and horizontal components of a projectiles displacement on a trajectory graph

A

verticle displacement- Total displacement* Sin(θ)

horizontal displacement- Total displacement* Cos(θ)

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27
Q

vertical and horizontal components of a projectiles velocity on a trajectory graph

A

vertical velocity- total velocity* Sin(θ)

horizontal velocity- total velocity* Cos(θ)

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28
Q

observed value

A

true value + Random error + systematic error

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29
Q

density

A

mass (Kg)/ Volume (m^3)

density in Kg/m^3

30
Q

pressure in a fluid

A

depth(m) * density of the fluid(Kg/m^3) * acceleration due to gravity(m/s^2)

31
Q

work done

A

force(N) * distance(m)

work done in joules (J)

32
Q

kinetic energy

A

1/2 * mass(kg) * velocity^2(m/s)

KE in joules(j)

33
Q

Δgravitational potential energy

A

mass(kg) * g(m/s^2) * change in hight(m)

GPE in joules(j)

34
Q

wave intensity

A

power(W) / Area(m^2)

intensity- W/m^2

35
Q

elastic potential energy

A

1/2 * spring constant (N/m) * extension^2 (m)

EPE in joules(j)

36
Q

power

A

energy transferred(j) / time(s)

power in Watts(W)

37
Q

power (using velocity)

A

force(N) * velocity(m/s)

power in Watts(W)

38
Q

efficiency

A

useful energy(j) / total Energy (j)

*100 if you want %efficiency
no units

39
Q

force on a spring

A

spring constant(N/m) * extension(m)

Force in Newtons (N)

40
Q

stress

A

force along the axis (N) / cross-esctional area(m^2)

stress in pascals(Pa or N/m^2)

41
Q

strain

A

extension(m) / original length(m)

strain has no units

42
Q

youngs modulus

A

stress(N/m^2) / strain

43
Q

newtons second law

A

Force(N)= Mass(kg) * acceleration (m/s^2)

44
Q

impulse

A

Force(N) * time(s)

impulse is in kg m/s

45
Q

charge

A

current(A) * time(s)

charge in coulombs (c)

46
Q

Potential Difference

A

work done(j) / charge(c)

potential difference in volts(v)

47
Q

Electromotive force

A

(cells internal resistance(Ω) + circuit resistance(Ω) ) * current (A)

EMF in volts (v)

48
Q

Ohm’s law

A

voltage(v) = current(A) * resistance(Ω)

49
Q

the resistivity of a wire

A

(resistance(Ω) * cross sectional area (m^2)) / wire length(m)

resistivity in ohms (Ωm)

50
Q

three equations for electrical power

A

current(A) * voltage(V)

current^2(A) * resistance(Ω)

voltage^2(V) / resistance(Ω)

power in Watts(W)

51
Q

internal resistance

A

(electromotor force(V) - voltage(V) ) / current(A)

internal resistance in ohms (Ω)

52
Q

specific heat capacity equation

A
energy required(j)= 
mass(kg) * specific heat * Δtemp(k)

specific heat in joules per kilogram per kelvin

53
Q

specific latent heat equation

A
energy required(j)=
mass(kg) * latent heat (j/kg)
54
Q

three equations using the Boltzmann constant

A

ideal gas constant * moles(mol) =
Boltzmann constant * number of molecules

Avogadro’s constant =
ideal gas constant / Boltzmann constant

pressure(Pa)*volume(m^3) =
number of molecules * Boltzmann constant * temp(k)

55
Q

work done by an expanding gas

A

pressure(Pa) * Δvolume(m^3)

work in joules (j)

56
Q

atomic mass unit

A

1.66*10^-27 kg

57
Q

the equation for radiation pressure

A

pressure(Pa) * volume (m^3) =

1/3 * number of molecules * mass(kg) * velocity^2 (m/s)

58
Q

angular velocity

A

Δangle(rad) / Δtime(s)

angular speed in radians per second (rad/s)

59
Q

arc of a circle segment

A

angle(rad) / radius(m)

arc in metres (m)

60
Q

velocity (from angular velocity)

A

the radius of the circle(m) * angular velocity(m/s)

velocity in m/s

61
Q

circular motion’s period

A

1 / circular motions frequency(hz)

period in seconds (s)

62
Q

angular velocity (from period and frequency)

A

2π * circular motion frequency(hz)

2π / circular motion period(s)

angular velocity in rad/s

63
Q

3 equations for centripetal acceleration

A

Δvelocity(m/s) / Δtime(s)

velocity^2 (m/s) / radius(m)

angular velocity^2 (m/s) * radius(m)

acceleration in m/s^2

64
Q

the simple harmonic motion equation

A

acceleration(m/s^2) =

-(angular velocity^2) (m/s) * displacement(m)

65
Q

maximum acceleration of simple harmonic motion

A

angular velocity^2(m/s) * maximum displacement(m)

acceleration in m/s^2

66
Q

period of a spring with a mass on

A

2π * root( mass(kg) / spring constant(N/m) )

the period in seconds(s)

67
Q

displacement in simple harmonic motion

A

amplitude(m) * Cos(angular velocity(m/s) * time(s) )

displacement in metres (m)

68
Q

amplitude in simple harmonic motion

A

Cos(angular velocity(m/s) * time(s) ) = 1

amplitude in metres(m)

69
Q

maximum speed in simple harmonic motion

A

angular velocity(m/s) * amplitude(m)

speed in m/s

70
Q

period of a pendulum

A

2π * root(length of string(m) / gravity(m/s^2) )

the period in seconds (S)

71
Q

gravitational force

A

(gravitational constant * first mass * second mass) / the distance between the two objects ^2

72
Q

gravitational field strength

A

the gravitational force on the object

/mass of the object