Waves and sound

What is a medium?

The means by which someone is communicated

What are mediums made of ?

Particles and matter

forces are either..

A push or pull

When does a disturbance occur?

When a force is applied to the particles in the medium that causes s the particles to be moved

what is energy

fuel that makes matter go

how do waves move?

by transferring energy from one particle to the next through conduction (hitting each other)

Distance

Total path travelled

Displacement

Change in position

What are the 4 different type of mechanical waves

• transverse waves

• Longitudinal waves

• Torsional waves

• Surface waves

How are transverse waves created?

Vertical forces making the particles vibrate perpendicular

How are longitudinal waves created?

Horizontal forces causing the particles to vibrate parallel (0 degrees)

Mathematically, how are transverse and longitudinal waves represented as?

Sine functions

How are torsional waves created?

By torsional forces causing particles to twist around the medium (or rest axis)

Definition of Mechanical Waves

A wave is the transfer of energy over a distance in the form of a disturbance that travels or propagates, without the transport of matter (no displacement of particles), through a medium.

Surface Waves

Have particles in the medium that move up and down as well as back and forth in an overall circular motion

Cycle

A cycle is a complete sequence of motion that repeats itself.

• Note: It has the same starting and ending point.

Amplitude (A)

Is the maximum displacement of a particle from its rest position

• NOTE: also known as angle

bigger amplitude =…

more wave energy

What is a wavelength?

the length between any two consecutive points in phase

1 Wavelength is equal to…

• 1 Lamba (λ)

• 1 complete cycle

• 360 degrees

what is a crest?

The maximum value of upward displacement within a cycle

What is a trough?

the minimum or lowest point in a cycle.

1 crest (1/2 λ) + 1 trough (1/2 λ) =…

1 circle (1 λ)

Leading edge

Any particles moving away from the rest axis

Trailing edge

Any particles moving towards the rest axis

What is a phase?

The specific motion of the particles in a wave at a particular instant in time

Particles in phase

Any two particles that pass through the rest axis (position) at the same time in the same direction

• NOTE:

• Point A and E are 360 degrees apart (1 λ)

• Point A and H are 720 degrees apart (2 λ)

Particles in opposite phase

Any two particles (E and I) that pass through the rest axis (position) at the same time in the opposite direction

• NOTE:

• Point A and C are 180 degrees apart (1/2 λ)

• Point A and K are 540 degrees apart (1.5 λ)

out of Phase

Any other possible combination that does not match those stated previously

what is the relationship between frequency and amplitude

no relationship

what is the relationship between frequency and mass?

no relationship

what is the relationship between frequency and length?

inverse

what is the relationship between frequency and gravity?

root

What is frequency?

What is the number of cycles per unit of time

what is the frequency equation?

f = number of cycles/total time (s)

What is a period?

The time required to complete one cycle

what is the period Equation? (T)

T = total time (s) / number of cycles

The relationship between Frequency and Period is

inverse

• f a 1/T

What do physicist believe about sound?

A physicist believes sound is the cause, not the result it has on the auditory nerve or ear. Sound is simply a form of energy created by a vibrating object.

What type of wave is sound?

sound is a longitudinal wave.

who proved sound sound could not travel without a medium?

Otto Von Guericke

what is the tympanic membrane?

the eardrum

what is infrasonic

Sounds which have a frequency below 20 Hz

what is the normal sound range

frequency between 20 Hz and 20 000 Hz.

what is ultrasonic?

Sounds which have a frequency above 20 000 Hz

what does sound intensity measure?

measures the amount of energy hitting a square meter every second

Increasing wave Area =…

Decreasing wave amplitude

the relationship between sound intensity and distance from the source is….

Inverse squared (I a 1/d²)

hearing loss as a function of age is called

presbycusis

mosquito tones are

High frequency “mosquito” tones where originally created to disperse youngsters in front of stores, now kids are using them on their mobile phones

higher desnity mediums =…

higher speeds

speed of sound equation

332 + .59(t)

• Note

• T = temperature in Celsius

• V = the speed of sound in m/s

what is the universal wave equation

V = fλ

• V = Speed

• F = frequency

• λ = wavelength

Constructive Interference occurs…

when the resultant wave amplitude is larger than that of either of the original wave amplitudes.

Destructive Interference

Occurs if the waves push the medium in opposite directions, which means the resultant displacement (wave amplitude) is smaller than that of either of the original wave amplitudes.

Anti – Nodal lines

Constructive interference

The changing volume of music while playing is called…

dynamics

what do you hear when 2 tuning forkks are played at the same time and their frequencies are the same?

symptehtic vibrations

what do you hear when 2 tuning forks are played at the same time and their frequencies are the different?

sound gets softer and then louder

who is the doppler effect named after

Christian doppler

Sound is a…

Pressure

What is the relationship between all the harmonics?

Multiples of F0

What are the 4 factors that effect frequency of a guitar string

• length

• Tension

• Density

• Diameter

doppler effect equation

fp = fo (v +_ vp/v +_ vo)

*+_ means plus or minus

The 6 wave behaviors are

• Reflection

• transmission

• refraction

• diffraction

• absorption

• scattering

reflection

wave bounce off surfaces or boundary changes

transmission

The part of the wave that is not reflected but passes through the material

refraction

waves bend as they enter a new medium

Diffraction

The circular spreading of a wave as it passes through an opening or passes an obstacle.

NOTE:

• Diffraction increases as the size of the slit (aperture “A”) or object approaches the same size as λ

absorption

when all or part of the wave is prevented from reflecting or being transmitted

Scattering

Diffuse Reflection:

• A rough surface causes the wave to reflect in many directions

Specular Reflection

• Allows for clear images to form on objects

What happens to the amplitude, phase, and wavelength in a fixed-end reflection?

Amplitude

• No change

Phase

• 180-degree change ( became a trough)

Wavelength

• No change

What happens to the amplitude, phase, and wavelength in a free-end reflection?

Amplitude

• No change

Phase

• No change

Wavelength

• No change

what is the relationship between frequency and wavelength in a standing wave?

as the frequency increases, the wavelength decreases and vice versa

What are anti-nodes or super creates

a point of maximum constructive interference

how are anti-nodes or super creates made

by constructive interference

What are the conditions or criteria for a standing wave to be created?

2 waves travelling in opposite directions equal waveleng and equal amplitude OR frequncy

wavelength

the length between any 2 consecutive points in phase

rarefaction

A rarefaction is a region in a longitudinal wave where the particles are furthest apart

principle of superposition

when 2 or more waves act simultaneously on the same particles of a medium, the resultant displacement of the particle is the sum of the individual displacements of the wave at that point

what causes a wave?

A wave is caused by a disturbance that transfers energy through a medium or space, often described by oscillations or vibrations that propagate away from the source.

amplitude

the maximum displacement of a particle from its rest position

frequency

the number of complete cycles of waves passing a point in unit time

cycle

a complete sequence of motion that repeats itself

in phase

any 2 particles that pass through the rest axis (position) at the same time in the same direction

doppler effect

beat frequency

what is sound

universal wave equation

resonance

sound waves are…

longitudimnal waves