module 3: waves

What is a wave?

A disturbance through which energy travels from one place to another in a medium (like air or water - and through empty space i.e. light wave)

Child swinging on swing - what type of motion is this?

oscillatory motion

Pendulum swinging back and forth - what type of motion is this?

oscillatory motion

Guitar strings going up and down - what type of motion is this?

oscillatory motion

What is oscillatory motion?

Repetitive moton about a mean position, aka going back and forth about an equilibrium

Does sound travel faster in air, liquid or solids? Why?

Sound travels fastest in SOLIDS - where the particles are packed closely together so vibrations pass quickly from one to another... followed by liquids.

Gases on the other hand (i.e. air) are more compressible (particles are further apart) so sound moves slower bc the vibrations passing is not as fast.

How do noise cancelling earphones work? What is this an example of?

ANC earphones analyse sound waves around you and generate a sound wave that DESTRUCTIVELY INTERFERES with that wave, cancelling it out!

What happened to the London Millenium Bridge? What was this an example of?

The London Millenium Bridge disaster occured due to oscillation and resonance!

Resonance can increase the amplitude of an oscillation by applying force at just the right frequency…

i.e. swinging kid higher on swing at just the right moment

Londoners swayed into the bridge, creating another frequency similar to the natural frequency of the bridge. This created resonance and caused a swaying London Bridge! 😐

Can sound travel thru a vacuum?

FALSE - sound cannot travel thru a vacuum - they are mechanical waves that need particles to vibrate and pass the disturbance along - vacuum dont have particles

Is the speed of sound constant?

TRUE, the speed of sound is constant!

Is loudness of sound directly related to its amplitude?

TRUE, loudness just refers to sound INTENSITY, which I is proportional to amplitude squared!

Is the pitch of soud determined by its frequency?

TRUE, the pitch of sound is determined by its frequency, which is the number of vibrations or oscillations per second, measured in Hertz (Hz).

Higher frequencies correspond to higher pitches, while lower frequencies correspond to lower pitches.

The human ear can typically hear frequencies ranging from about 20 Hz to 20,000 Hz (20 kHz), and sounds within this range can be perceived as higher or lower in pitch depending on the frequency