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5.1Unit 6: Sound, the Earth and eclipses

Sound waves — Cambridge Checkpoint Earth & Space 0893 Revision Notes & Topical Questions

5 min read 13 parts Lesson 1 of 5 1 quiz

📚 Cambridge Checkpoint Earth & Space 0893 Hub / Topical Revision
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Lesson summary

5.1 Sound waves — CHECKPOINT EARTH AND SPACE 0893 notes: Explain that sound comes from vibrations, travels as a wave through particles and cannot travel through a vacuum.Vibrate = to move backwards and forwards very quicklySource — things that vibrate make soundsDrum — hitting a …

  • Loudspeaker
  • Wave direction
  • Very loud sounds
  • Very quiet sounds
  • Solids, liquids and gases
  • Tight string

Section 1 of 13Sound and vibration

Vibrate
Vibrate to move backwards and forwards very quickly
Source
  • Source things that vibrate make sounds
Drum
  • Drum hitting a drum makes it vibrate, and hitting it harder makes it vibrate more and sound louder
Voice
  • Voice vibrations of the vocal cords make the sound when you speak
Loudspeaker
  • Loudspeaker its paper cone vibrates, which small objects placed on the cone show by bouncing

Section 2 of 13Loudness and pitch

Variation
  • Variation sounds differ in loudness and pitch
Pitch
  • Pitch thunder has a low pitch and a crying baby has a high pitch
Loudness
  • Loudness a bigger vibration gives a louder sound
Guitar
  • Guitar plucking the string with more force makes a louder sound

Section 3 of 13How a sound wave travels

1
A vibrating object moves forwards and pushes the air particles in front of it.
2
Those air particles vibrate backwards and forwards in time with the object.
3
They make the particles in front of them vibrate.
4
The vibration passes from particle to particle as a sound wave.
5
The wave reaches the ear and the ear detects the vibration.

Section 4 of 13Particle movement in a sound wave

Particle movement in a sound wave
Particles
  • Particles they vibrate backwards and forwards along the direction in which the wave travels
Wave direction
  • Wave direction the wave moves away from the source, but the particles do not travel with it
Speed
  • Speed sound travels through air at about 343 metres per second
Energy
  • Energy sound waves transfer sound energy, and the vibration passes to other objects, which then vibrate

Section 5 of 13Effects of sound vibrations

Very loud sounds
  • Very loud sounds their vibrations can damage the ears
Very quiet sounds
  • Very quiet sounds their vibrations may be too small for the ears to detect
Pitch
  • Pitch a sound at a certain pitch can cause damaging vibrations even when it is not very loud
Objects
  • Objects vibrations from a high-pitched sound can break glass

Section 6 of 13Media for sound

1Medium
Medium the substance a sound wave moves through
2Solids, liquids and gases
  • Solids, liquids and gases all can be a medium because they contain particles
3Gas
  • Gas sound travels through air
4Solid
  • Solid sound travels easily through a table when an ear is placed on it
5Liquid
  • Liquid sound travels through water, which whales and dolphins use to communicate
6Same way
  • Same way in all three states the wave makes particles vibrate backwards and forwards

Section 7 of 13No sound in a vacuum

Needs
  • Needs to hear a sound there must be a vibration and a medium with particles
Vacuum
  • Vacuum a space with no particles, so there is nothing to vibrate and no sound wave can travel
Space
  • Space space is a vacuum, so sound cannot travel through it and the Sun could not be heard
Bell jar
  • Bell jar an electric bell in a jar can be seen vibrating, but its sound cannot be heard once the air is pumped out

Section 8 of 13Modelling a sound wave with a spring

1
Stretch a slinky spring across a smooth flat surface.
2
Mark positions on the spring with chalk or pieces of paper to represent particles.
3
One person holds one end still.
4
Another person moves the other end backwards and forwards.
5
Observe that the wave travels along the spring while each mark only moves backwards and forwards.

Section 9 of 13String telephone investigation

Set-up
  • Set-up two cups joined by a long string, with one person speaking quietly into one cup and another listening at the other
Tight string
  • Tight string the voice is heard because the sound wave passes through the string
Slack string
  • Slack string the sound is not heard or is much weaker
Gripped string
  • Gripped string gripping the string stops the vibrations, whatever position it is gripped at
Conclusion
  • Conclusion sound needs vibrations passing through a medium to travel
Fair test
  • Fair test speak with the same loudness each time, for example by using a recording

Section 10 of 13More from the specification

Compression
  • A region in a longitudinal sound wave where particles are crowded together, corresponding to higher local pressure and density.
Rarefaction
  • A region in a longitudinal sound wave where particles are spread furthest apart, corresponding to lower local pressure and density.
Oscillation
  • The repetitive back-and-forth vibrating movement of particles about a mean resting position.
Frequency and Pitch
  • Frequency is the number of complete vibrations per second in hertz (Hz);
    • higher frequencies produce higher pitched sounds.
Amplitude and Loudness
  • Amplitude is the maximum displacement of particles from equilibrium;
    • waves with greater amplitude carry more energy and sound louder.

Section 11 of 13More from the specification

More from the specification
Acoustic wave frequency groups
  • Acoustic wave frequency groups classifying oscillating compression waves into ultrasonic and audible groups relates frequency to physical sound perception.
Vibrational origin of sound
  • Sounds originate from mechanical vibrations of a source that displace neighboring particles in an elastic medium.
Acoustic compressions and rarefactions
  • Sound waves propagate via alternating zones of elevated density (compressions) and reduced density (rarefactions).
Pitch and frequency relationship
  • Pitch is the human sensory perception of acoustic frequency;
    • high frequencies sound high-pitched, while low frequencies sound bass/low-pitched.
Speed of sound across states of matter
  • Sound travels fastest through solids, slower in liquids, and slowest in gases.
    • (densest particle packing)
Group
  • A column of the Periodic Table.

Section 12 of 13Key terms

TermMeaning
VibrationRapid movement backwards and forwards.
Sound waveVibration of particles that carries sound from a source.
MediumSubstance through which a wave travels.
VacuumSpace containing no particles.
PitchHow high or low a sound is.
LoudnessHow loud a sound is.
Speed of soundAbout 343 m/s in air.

Section 13 of 13Exam technique

1
Thinking sound travels through a vacuum — sound needs a medium with particles.
2
Thinking air particles travel from the source to the ear — the particles only vibrate backwards and forwards.
3
Thinking sound only travels through air — it travels through solids, liquids and gases.
4
Thinking a louder sound has a higher pitch — loudness depends on the size of the vibration and pitch on how fast it vibrates.

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