Key Notes, Formulas, and more for AS and A Level
Physics
(9702)
Physics CheatSheet
, Data 3. Action = equal and opposite reaction Impulse Volume is DIRECTLY related to Intensity
Scientific Method Uncertainty -can’t have only one force A change in momentum (how you feel p change) Volume is DIRECTLY related to Frequency
F a, b = - F b, a f standard = 1,000 Hz.
1. Observation * units (metrics) Normal Force
Force : F = m a F = m Δ v
Δt Intensity Range
2. Define the Problem * measuring - able to change until breaking point of Time : * hidden variable* Threshold of hearing (Io) = 1 x 10 -12 w / m 2
3. Test/Experiment * sig. figs. whatever it’s holding FΔt = mΔυ = Δp Threshold of sound = 1 w / m 2
4. Hypothesis * Data - acts perpendicularly to “holding” object Conservation of Momentum β = 10 log ( I )
5. Collect Data/Manipulate Manipulation - comes from ground (except water) In the absence of an external force, the total 1 x 10 -12 w / m 2
6. Conclusion Newtons momentum of a system is constant ”How many powers of 10 are in that number?”
Accuracy vs. Precision 1 N = 0. 225 lbs. Mass is constant m1 υ 1 + m2 υ 2 = m1 υ 1 + m2 υ 2 Decibel = w / m 2 .
Accuracy – closeness of results to a standard F= ma ------ Fw = mg N kg (/ 9. 8) Work ( J ) w / m2
Precision – closeness of results to each other Kg N (x 9. 8) * Need to apply force W=Fd Pitch and Tone
*use same piece of equipment to collect data* Friction (Ff) * implies motion I volume f pitch
Qualitative vs. Quantitative 1. two or more things must be touching Power ( watt -- w ) Notes and tones : pitch with recognizable frequencies
Qualitative – more on precision than accuracy 2. energy is transferred (heat, sound, etc) P = W . = (F d) Laws of Pitch:
Quantitative – numbers count and are important
Sig. Figs.
3. texture matters… NOT SURFACE AREA
μ = coefficent of friction (Ratio of
t
J = 1 w = N m = 1 kg m2
t
1. f is INDIRECTLY related to length
2.
2
parallel force to perp. Force) s s s
Addition and Subtraction: f is DIRECTLY related to tension (Ft)
μ = Ff (3 decimal places) 1 horse power = 746 w
*least # places after decimal
Multiplication:
*places after decimal count as sig. figs.
FN
Ff = μ m g Ff = Fw (on flat surface)
Energy
Ability to do work 3. f is INDIRECTLY related to diameter (d)
2 . 5 cm = 1 in
μ = tan θ (when υ is constant)
Pressure: P = Force/area
Mechanical: energy of motion or position
Kinetic (K) : motion 4. f is INDIRECTLY related to density (D)
4. opposes motion which causes decelleration K = ½ m υ 2 (J) Beats : the resultant interference pattern of 2 notes
Vectors Potential (U) : position close in frequency but not exact
Vectors (velocity) – has BOTH magnitude and direction 5. static – “starting Ff” not moving (rolling) U = m g h (J) (W = F d) Creat nodes (sharps and flats)
Scalars (speed) – has magnitude ONLY greater force than kinetic When not given distance…(or force) Doppler Effect : the apparent change in frequency of
*time, mass, volume kinetic – moving (rolling, sliding, fluid) W = ½ m υ 2 - ½ m υ o2 (W = ΔK) a sound due to the relative motion of either the observer
Metric System Abbr. (K final) – (K initial) or the source of both
Mm - km - hm - dkm - m Conservation of Energy Resonate : when you cause something to vibrate at
Equilibrium
dm - cm - mm - Mm(E-6) - nm(E-9) Energy change from one to the other w/o any net loss its natural frequency
------------------------------------------------------------------------------------------------------- Translational: the sum of forces equal zero
Mult. Component Vecctors Rotational: the sum of torques equals zero UTOP = KBOT (mgh = 1/2mv2) Music repeating wave pattern
1. 18m due S Complete: must have BOTH Noise no repeating wave pattern
Center of Gravity : center of distribution of mass Wave Motion Consonance sounds GOOD
2. 22m, 47deg. S of W
Torque Simple Harmonic Motion Dissonance sounds BAD
3. 10 m, 78deg. N of W
Force with leverage causes rotation A repeating motion in which the acceleration is Decibel:
4. 30 m due E
Leverage: distance from fulcrum to force directly related to the displacement (distance away from I B .
*(W&E) Sum of the
*Directly related to torque the equilibrium) and always directed towards 1 x 10 –12 0 db
Vχ= (0)+ (-22 cos47)+(-10 cos78)+(30) =12. 9m
τ = F (perp.) l equilibrium. 1 x 10 –11
10 db
*(N&S) Sum of the
-------------------------------------------------------------------------------------------------------
Vχ= (-18)+ (-22 sin47)+(10 sin78)+(0) =-24. 3m -
1 x 10 –10 20 db
*Resultant υ = Circular Motion --- ---
–2
((12. 9)2 + (24. 3)2)1/2 =27. 5m Moving at a constant speed while accelerating f = 1/T 1 x 10 100 db
* θ = tan-1(24. 3) A = v speed: constant Cosine Curves 1 x 10 –1 110 db
(12.9) = 62.0deg dxn: constantly changing Y = A cosB (x – C) + D 1 120 db
R= 28m, 62deg S of E A = amplitude ( 0) : how much energy it has Natural Frequencies l = 170 / Hz
------------------------------------------------------------------------------------------------------- Centripetal Acceleration CosB = period ( 2 PIE / t) : time, 1 oscillation Brass/String n name synm wavl (λ) l f
Inward seeking Ac = υ 2 . C = horz. Shift : human error f fund. 1st har. 2l ½ λ v/2l
Kinematics r D = vert. Shift : distance, to x-axis f 2 1st ov. 2nd har. l λ v/l
Displacement Centripetal Force Waves f 3 2nd ov. 3rd har. 2/3l 3/2 λ 3v/2l
If + it’s AWAY Causes centripetal acceleration * Graphed SHM, transfer of energy f 4 3rd ov. 4th har. 1/2l 2 λ 2v/ l
If – it’s TOWARD Fc = m Ac (F = m a) Vibration : WORK to get energy fn= n υ hn = 2 l fn = Nf1
Fc = m υ 2 . (N) Propagates : what energy moves through 2l n
Velocity (m/s)
r Mechanical (light) Electromagnetic (sound) Woodwind n name synm wavl (λ) l f
Use ONLY when SPEED is CONSTANT
You MUST have cent. F to keep something Needs a medium does NOT need a medium f fund. 1st har. 4l 1/4 λ v/4l
1. does not include acceleration
moving in a circle More dense – better less dense – better f 2 ------ ------- ----- ----- ----
2. does not include starting and stopping
Centrifugal: body’s interpretation of cent. F Mechanical Waves f 3 1st ov. 2rd har. 4/3l 3/4 λ 3v/4l
in the same place
Transverse : medium vibrates perp. to energy f 4 ------ ------- ----- ----- ----
DOES NOT EXIST feels inertia
Most common ex. Guitar string, slinky f 5 2nd ov. 3rd har. 4/5l 5/4 λ 5v/4l
v= χ Rotation: spinning on axis within object
Longitudinal : medium vibrates para. to energy fn=nυ hn = 4 l
t Revolution: spinning on axis outside of object
Has compressions ex: sound 4l n
Acceleration (m/s/s) Linear / Angular
Surface : both para. and perp. to energy Instruments
*speeding up or slowing down Linear : speed = distance / time radius matters
“physics bob” ex: earthquakes, waves String
a= v 57. 3deg = 1 RADIAN
Principle of Superposition Produced by: plucking string, bowing
t 1 rotation = 2 π Radians = 360 degrees
Constructive Interference : added Change pitch : length, diameter, tension, density
Kinematic Formulas Angular: speed = # rotations or revolutions / time
Deconstructive : subtracting (adding negatives) Brass
X Direction Y Direction radius does NOT matter
V= λ_ V = λf Produce by : buzzing mouth piece
υ=υo+at -gt * by doubling the angular speed
2 T Change pitch : length of pipe (valves), buzzing
χ = χ o + Vo t + ½ a t -½gt2 you double the # of rotations
Standing Wave Woodwind
χ = χ o + ½ (υ + υ o) t ------ Linear Angular
A continuous wave train of equal amplitude (RAD), Produced by : reed vibrating
υ 2 = υ o 2 + 2 a ( χ - χ o) -2g( χ (m) χ=rθ θ (RAD)
wavelength (m), and frequ. (Hz) (/sec) in the same Change pitch : pads, holes
Change χ (o) to Y(o) υ (m/s) υ = r ω ω (RAD / s)
medium creating nodes and antinodes. Edge tones: narrow streams of air split by edge
Projectial Motion a (m/s/s) a = r α α (RAD / s / s)
Boundary : change in medium Helmholtz Resonance: edge tone with bottle (open
Half F (N) Ft = τ τ (Nm)
(part of energy gets reflected, part gets absorbed) hole)
* Y determines time in air Mass (m) I (mr)
rigidity : how much energy gets ABSORBED ---------------------------------------------------------------------
*compliment angles of 45deg have same range F=ma τ=Iα
close rigidity more absorbed Light
X . . Y . For linear ω=ωo+αt
different rigidity more reflected Particle Wave
χ=Vχt Y=½gt2 See other corner θ = θo + ω o t + ½ α t 2
Interference in Diffraction + Newton said so + Thomas Young – 2 slit ex
T= χ θ = θ o + ½ (ω + ω o) t
Crest + crest = antinode Crest + troph = node + Beams / Waves + reflection, refraction,
Vχ ω 2 = ω o 2 + 2 α (θ - θ o) ------------------------------------------------------------------------------------------------------- + travel in straight lines diffraction, interference
Full Rotational Inertia -
+Hertz – light is energy
* 45deg has max. range Resistance to begin or stop rotation Sound + Einstein – wave particle duality
Steps: A range of longitudinal wave frequ. to which the
1. υ o cos θ o / υ o sin θ o
• Depends on amount of mass AND where human ear is sensitive
Polarized Light: Light oriented to one plane (calc.)
Liquid Filter Display : lets only one degree of light in
it is placed Infra sonic sonic spectrum ultra sonic Visible Spectrum :
2. Find the TIME (check Y) (below 20 Hz. ) (20 Hz – 20,000 Hz) (20,000 Hz +)
Solid Sphere 2/5 mr2 Solid Disk ½ mr2 Radio * Micro * Infrared * Ultraviolet * Xrays* Gamma
3. Find the height / range
X . Y . Hollow Sphere 2/3 mr 2 Hollow Disk 1 mr2
• Velocity is indirectly related to Inertia
1. production : needs vibration Big wavelength Small wavelength
Red Orange Yellow Green Blue Indigo Violet
χ=Vχ t t= 2υo .
(Vx = υ o cos θ o) g • Shape of object spinning makes the 2. transition : needs a medium air Transparent: see through it and light passes
(Windows, glass)
(V o = υ o sin θ o) difference while spinning
y max = υ o 2 3 Forces acting upon an object in circular motion 3. reception : must be heard Translucent: can NOT see through it, light passes
(frosted glass)
2g
--------------------------------------------------------------------- 1. Centripetal Acceleration (Ac)
V sound = 340 m/s
V sound = 331 + . 6 (Temp.)
Opaque : can NOT see through it, NO light passes
Source: makes and emits light
Force (N) 2. Angular Acceleration (α)
Intensity : measurable
How loud a sound is * the time of flow of energy
Luminous: sun
- Causes a change in motion (causes acceleration) 3. Linear Acceleration ( a ) Luminate: moon
per unit area
- Is a VECTOR quantity ------------------------------------------------------------------------------------------------------- Light Year: takes 8. 3 min. to get light from sun
- I = Pow . ( P=W)
Equilibrium – no acceleration , forces cancel , “at rest” Dispersion: breaking up light into colors (prism)
Amp t
Newton’s Laws of Motion Colors
Conservation Laws Intensity is DIRECTLY related to amplitude
1. An object at rest will remain at rest until acted Cones in eye pick up 3 primary colors of light
Momentum ( N s ) Damping : further you get from the center quieter Additive
upon by an outside force Moving inertia (Newton’s 2nd law) it will be
INERTIA – directly related to mass Primary Secondary
Momentum IS inertia…Inertia is NOT momentum Inverse Square Law : I1 r12 = I2 r22 BLUE YELLOW
2. Acceleration is directly related to Force
Momentum is DIRECTLY related to mass and speed
p = m υ (N s)
RED
GREEN
CYAN
MAGENTA
indirectly related to mass • causes body to want to fly off tangent Volume (B): subjective (decibels)
F=ma (1 kg m / s2 = 1 Newton) * More than one light source
Relative Intensity Level loudness level
