physics notes set 2

8/3/2019 Physics Notes Set 2

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Fluids

substances that can flow and can easily change in shape usually are liquids and gases

Fluid Mechanics

Fluid Statics

study of fluids at rest

Fluid Dynamics

study of fluids inmotion

Density Pressure BuoyancySurfaceTension

Bernoullis PrincipleArchimedes

PrinciplePascalsPrinciple

Density

ratio of mass of a substance to its

volume independent to the amount present in a

substance

(rho)

Pressure force per unit area P Kinds of pressure

hydrostatic pressure exerted on an object by a column of liquid

air/atmospheric pressure exerted on an object by air

A barometer is an instrument used to measure pressure. It was invented byEvangelista Torricelli.

Pascals principle (by Blaise Pascal) states that for any change in pressureapplied at any given point on a confined fluid is transmitted undiminishedthroughout the fluid

Buoyancy is the apparent loss of weight of objects when submerged in aliquid

Buoyant force () is the upward force exerted by water that seems tobalance the force of gravity

Archimedes principle states that a body partly or entirely submerged in afluid is buoyed up by a force equal in magnitude to the weight of the displacedfluid


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Scale Interval ProponentH2O

BoilsH2O

FreezesConversion

Celsius 100AndersCelsius 100C 0C

()

Fahrenheit 180DanielGabriel

Fahrenheit212F 32F

Kelvin 100 Lord Kelvin 373K 273K Linear Thermal Expansion wherein: is the length of an object, is the linear thermal expansion coefficient ( or ) is the temperature in Kelvin or degrees Celsius

Volume Thermal Expansion wherein: is the length of an object, is the volume thermal expansion coefficient ( or ), and is the temperature in Kelvin or degrees Celsius

Three modes of heat transfer:1] Conduction direct contact

conductors are materials that conduct heat well; has loosely-boundelectrons

insulators are materials that delay heat transfer2] Convection currents in the fluid3] Radiation through electromagnetic waves

hotter objects emit shorter wavelengths while colder objects emit longerwavelengths

Specific heat capacity is the amount of heat needed to change thetemperature of a quantity by 1C

wherein:

is change in temperature, is the specific heat capacity constant, is the mass of the object, and is change in heatThe SI unit of specific heat capacity is

or ()Latent heat is the amount of energy/heat given out / absorbed when a

substance changes phase which do not change in temperature

Latent heat of fusion () is the amount of heat that must be added to asubstance at its melting point to change from solid to liquid Latent heat of vaporization () is the amount of heat that must be added to a

substance at its boiling point to change from solid to liquid


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History of Wave and Harmonics

19th

century BC birth of acoustics and optics

14th

century BC the interest in musical instruments prompted the mathematical

study of vibrating bodies and of the propagation of sound throughair

4th

century BC Pythagoras established the connection between musical soundsand mathematics

Robert Hooke and Christian Huygens believed light to be a form of wavemotion

Thomas Young (1800) firmly established the wave nature of light Heinrich Hertz (1886) established that radio waves were of the nature of light

waves

AM radio waves are measured in kHz while FM radio waves are measuredin MHz

20th century wave concepts were used to develop the theory of quantummechanics called wave mechanics

Vibration is the periodic or repeated motion of a particle or mechanicalsystem.

Simple harmonic motion is the back-and-forth vibratory motion of a swingingpendulum wherein the restoring force is proportional to the displacement from theequilibrium.

Hookes Law:

wherein: is the spring constant; and is the change of length of the spring

Types of waves:1] According to the medium requirement:

A] Mechanical waves waves that require a medium (water waves, soundwaves, waves that move along a rope or a string)

B] Electromagnetic waves waves that does not require a medium2] According to the number of travelling pulse:

A] Pulse waves single travelling pulseB] Periodic wave continuous generation of pulses3] According to the direction of motion

A] Transverse wave have vibrations that are at a right angle or perpendicularto the direction of the wave

B] Longitudinal wave have vibrations that are along the direction of the waveC]Surface wave is a combination of both transverse and longitudinal waves.

Measure of awave

Description FormulaSI

Unit

wavelength ()

distance between two consecutive

crests or troughs m

period (T) time to complete one cycle

s

frequency (f)the number of complete waves orcycles per unit time

Hz


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amplitudethe displacement from the midpoint tothe crest/trough of the wave

m

wave speed (v)depends on the medium through whichthe wave moves

m s

wave energy (E)energy carried by the wave isproportional to the frequency of thewave

1 W

Characteristics of a Sound Wave:

we cannot see sound waves, but we can measure all their properties

composed of waves of compression and rarefaction (a sound wave is a

longitudinal wave) follows an orderly pattern

carries energy

Sound is produced when vibration causes pressure variations in the medium.

Propagation of sound:

travel through solids, liquids and gases but not in vacuum travel more efficiently in denser materials

propagates three-dimensionally (all directions)

approximately spherical

The human ear is an amazing sound detector

OuterEar

Three TinyBones:Anvil,

Hammer,Stirrup

Cochlea Auditory

Nerve Brain

Physical properties of sound waves:

1] Pitch perception of highness or lowness of sound depends on the frequency of sound waveA] audio frequency range: 20Hz 20 000HzB] ultrasonics: above 20 000HzC] infrasonics: below 20Hz Doppler Effect (Christian Doppler) is the change in frequency or pitch of a

sound that is caused by the movement of either the source, the listener, orboth blue shift is the increase in frequency due to the Doppler effect while the

red shift is the decrease in frequency due to the Doppler effect2] Loudness

sound level or intensity

determined mainly by the amplitude of the sound wave the threshold of hearing is 0dB while the threshold of pain is 120dB

1is the Plancks constant ()


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the second sound is noticeably louder than the first sound if the secondsound is 1dB higher than the first sound;the second sound is twice as loud as the first sound if the second sound is

10dB higher than the first sound;two equal sound levels combined will create a sound that is 3dB higher thantheir original volume

3] Timbre tone color or tone quality

distinguish between two different sounds that have the same pitch andloudness

depends on the wave form of the sound wave

different wave forms creates different tone quality

Speed of sound doesnt depend on the source but on the medium through

which they move. It is dependent on the following:1] density since sound waves move well through dense materials because

their molecules are close together2] elasticity since sound waves move fast through elastic materials3] temperature since sound waves travel faster through warm air than through

cold air

has less effect on solids or liquids at 0C the speed of sound in gas is estimated to be about m s speed increases by about m s for every increase in temperature a supersonic boom will occur if a source moving at speeds greater than

the speed of sound that would cause the waves to pile up

Sound wave characteristics:1] Reflection

bouncing of wave an echo is any reflected sound heard shortly after the original sound

affected by two factors:A] properties of the reflecting sound since greater energy is reflected if the

surface is hard and smoothB] distance of the reflecting surface from the source since to hear an echo,

the sound source must be at least 17m away from the reflecting surface

2] Refraction sound waves bend or refract as they move through air (differences in air

densities)3] Diffraction

bending of sound waves due to a barrier or opening

greatest in high pitch sounds and less in low pitch4] Interference has two types:

Constructive Interference occurs when two waves combine with eachother and create another wave of higher intensity

Destructive Interference occurs when two waves combine with each other

and create another wave of lower intensity

Music vs Noise

pleasing combination of tones

regular pattern rhythm, harmony, melody, pitch, quality

random and irregular

unwanted sound


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Musical Instruments

String Instruments

produce tone when strings vibrate

higher vibration yields higher volume long and thick strings produce low pitch sounds while short and thin strings

produce high pitch sounds Wind Instruments

contain a column of air that vibrates when air is blown a long air column will produce a low pitch sound while a short air column will

produce a high pitch sound Percussion Instruments

produce sound when they are struck depends on how hard one strikes the instrument

pitch is affected by the tension on the drum covering


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Optics is the study of light

Nature of Light

light does spread out (ChristianHuygens on his Wave Theory ofLight)

light travels only in a straight line(Isaac Newton on hisCorpuscular Theory)

discovered the diffraction and interference of light which can be explained onlyin terms of wave theory (Thomas Young, 1801)

predicted that changing electric and magnetic fields can propagate throughspace as electromagnetic waves and light itself is an electromagnetic wave(James Clerk Maxwell, 1860)

discovered the existence of electromagnetic waves through radio wavesshared same property of light (Heinrich Hertz, 1880)

proposed that energy comes in discrete units called quanta (Max Planck,1900)

theorized that light is composed of bundles of wave energy called photons(Albert Einstein, 1905, on his Photoelectric Effect)

shared that photons of X-rays decreased in energy when colliding withelectrons (Arthur Compton, 1923)

light has a dual nature; behaves as both wave and particle (Louis Victor deBroglie, 1924)

Producing Visible Light

an illuminated object is an object that reflects light waves a luminous object is an object that gives off its own light

Two Ways to Produce Light incandescence

light is produced when the atoms of an object are heated

emitted nearly all extremely hot objects when temperature is lower, the wavelength is higher which will produce a

reddish color; conversely, when temperature is higher, the wavelength is

lower which will produce a bluish color luminance

only electrons of the atom are involved

no need for large amount of heat caused by the movement of electrons from higher to lower energy levela] Chemiluminescence

production of light as a result of chemical reactionb] Bioluminescence

production of light by organismsc] Fluorescence

production of light when excited by another source of radiation light ceases when external excitation stops

d] Phosphorescence

production of light when excited by another source of radiation luminescence persists even after the removal of the external excitation

Wave Particle

Christian Huygens Isaac NewtonThomas Young Max PlanckJames Clerk Maxwell Arthur Compton

Heinrich HertzAlbert Einstein


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Formation of Shadow

shadow formation is a proof that

light travels in a straight line size of shadow depends on the

distance of the point source andthe size of light source

The Speed of Light (c) is equal to Person Experiment Value

Galileo Galilei lantern experimentOlaus Roener studied the period of Io

Christian Huygens refined Roeners data Armand Hippolyte

Louis Fizean toothed wheel Jean Bernard LeonFoucalt

rotating mirror Albert Michelson octagonal mirror

Photometry is the measurement of the properties of lightLuminousIntensity

brightness of lightcandela

(cd)

LuminousFlux

(LuminousPower)

rate at which light is emitted from asource and strikes the surface of a

whole sphere

lumen

(lm)

Illuminance measures the amount of illumination lux (lx)

LuminousEfficiency

ratio of light flux emitted by thesource to the power supplied to thesource

Types of Materials

opaque materials absorb light waves that fall on them; absorb light without re-emission

translucent materials allow light to be transmitted through them but its raysare distorted during the passage

transparent materials transmit light waves and permit objects to be seenclearly through them; produce a chain of absorption and re-emission of light

Light Wave Interactions

reflection is the bouncing off of light waves diffraction is a kind of reflection wherein light strikes a rough, uneven

surface regular/specular reflection is a kind of reflection wherein light strikes a

smooth, flat surface refraction is the bending of light waves due to difference in density

law of refraction (Snells Law)

(index of refraction)

Ionized GasesColor Gas

red light Pure Neongreenish blue light Argon and Mercurygolden yellow light Helium

pure violet light Krypton


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total internal reflection occurs when light travels from a denser to lessdense medium and strikes the surface at an angle greater from the criticalangle, the light beam is not able to get out of the denser material

dispersion is the process by what light is separated into its colors due todifferences in degrees of refraction interference (Thomas Young on his Double Slit Experiment)

diffraction is the bending of light waves due to a barrier or opening Huygens Principle states that every point on any wave front of light from a

point source may be regarded as a new point source of secondary waves polarization occurs to a light wave if its vibrations are confined to a single

place a polarizer transmits only the wave that vibrates parallel to the alignment of

the crystals in it an analyzer transmits only the wave that vibrates perpendicularly to the first

polarized sheet

Colors

Isaac Newton made a systematic study of colors using his prism-spectrumexperiment

an object can reflect only light of frequency present in the illuminating light

Color Mixing

color mixing by addition mixing colored lights of different frequencies

white light has three regions, primary addition colors, which are red,green, and blue

color mixing by subtraction mixing pigments which absorb different frequencies of light

three regions, primary subtraction colors, which are magenta, cyan,and yellow

Mirrors

Plane Mirrors

flat surface Curved/Spherical Mirrors

Convex

curves outward diverging mirror

Concave

curves inward like a cave converging mirror

Parts of a curved mirrorVertex V

Center of

Curvature C center of the sphere from which the mirror is formedFocal Point F midpoint of C and VRadius ofCurvature

R distance from C to V

Focal Length Fdistance from F to V

Pigment Absorbs Reflects

R B G RG B R GB R G BY R R GC G G BM B B R


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Principal Axis PAline passing through C, F, and Vtangent to the curve of the vertex and perpendicularto the mirror

Parameters of mirrors

type (virtual/real) orientation (inverted/upright or erect) position (between/at point/beyond) size (smaller/larger/same size)

Ray Diagram

a ray parallel to the PA is reflected through the focal point, F a ray passing through the focal point, F, is reflected parallel to the PA a ray passing through the center of curvature, C, is reflected back along its

own path

The TOPS parameter of a concave mirrorLocation F ~ C C ~ F ~ V @ C @ F @

Type Real Real virtual real no image realOrientation Inverted Inverted upright inverted no image ???

Position C ~ F ~ C behind @ C no image FSize Larger Smaller larger same no image no image

Lenses are curved pieces of glass or some other transparent materials that are

used to refract light convex (converging) lens

thicker at the center than at the edges has six TOPS cases (see below)

concave (diverging) lens

thinner at the center than at the edges has only one TOPS case:

T virtualO uprightP ???S smaller

The TOPS parameter of a convex lensLocation F ~ C C ~ F ~ O @ C @ F @

Type Real Real virtual real no image realOrientation Inverted Inverted upright inverted no image ???

Position C ~ F ~ C F ~ O @ C no image FSize Larger Smaller larger same no image no image


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Mirror/Thin Lens Equation:

wherein is the focal length,

is the distance of the object and is the distance of the image.Magnification Equation:

wherein is the magnification, is the distance of the object, is the distance of the image, is the height ofthe object and is the height of the image.

physics notes set 2

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