Sound

Sound

1. How does sound travel?

   • When an object vibrates, it passes on the energy to the surrounding particles, pushing and pulling the layers of particles that surrounds it.
     • This causes compression and rarefaction
       • Compression is where air particles are closer together
       • Rarefaction is where air particles are further from each other
       • One complete vibration/wave consists of compression and rarefaction
   • Sound wave cannot transmit in vacuum because there are no particles

2. How does sound travel in different media?

   • Solids
     • Speed of sound: 6000 m/s
   • Liquids
     • Speed of sound: 1500 m/s
   • Gas
     • Speed of sound: 330 m/s
   • Factors that affect the speed of sound
     • Humidity
       • The higher the amount of particles packed in the air, the faster the speed of sound
     • Wind direction
       • Air molecules could be carried towards or away from the receiving end

3. How does sound vary?

   • Pitch
     • Frequency
       • High frequency: high pitch
       • Low frequency: low pitch
       • Measured in Hertz (Hz)
   • Loudness
     • Size of vibrations (or amplitude)
       • Large vibrations: loud sound
       • Small vibrations: soft sound

4. Uses of sound

   • For entertainment
     • Pleasant sound that is soothing to the ear
     • Noise is a collection of notes that is unpleasant and harmful to the ear
   • For Warning/Signal
     • Examples: Ambulance, traffic police car, fire alarm, lift breakdown, hissing from snakes
   • Sonar
     • SOund Navigating And Ranging

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