Sound and waves grade 6 pps
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Sound and waves grade 6 pps

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    Sound and waves grade 6 pps Sound and waves grade 6 pps Presentation Transcript

    • Sound
    • Overview
      • The Facts of Sound
      • Sound Vocabulary
      • The Ear and Sound
      • Musical Instruments and other uses of Sound
      • Other types of waves
    • The Facts
      • Sound …
      • … is a form of energy produced & transmitted by vibrating matter
      • … travels in longitudinal waves
      • … travels faster through solids than liquids or gases
    • Sound waves travel faster through solids because there are more particles close together to transfer the energy. Sound waves and
    • Speed of Sound
      • Medium (Matter) Speed m/sec
      • gas air (0 o C) 331
      • air (20 o C) 343
      • water (25 o C) 1493
      • liquid sea water 1533
      • iron 5130
      • copper 3560
      • solid glass 5640
      • diamond 12000
    • Vibration
      • Very fast, repeated backward and forward movement of particles of matter
      • For example, the vibration of the tuning fork creates pure sound.
      • The hammer hits the nail and the particles vibrate making noise.
    • Waves transport energy without moving matter Watch the 3 red dots You will see them vibrate , but not move with the wave to the end. All the particles are vibrating but stay fixed
    • Sound Waves
      • Alternating areas of high and low pressure in the air (compressions and rarefactions)
    • Sound Waves
      • ALL sound is carried through matter as sound waves. In a vacuum there are no particles so sound cannot travel.
      • Alternating areas of high and low pressure in the air (compressions and rarefactions)
    • Sound Waves
      • Because sound waves need particles to be transmitted they are mechanical waves
      • ALL sound is carried through matter as sound waves. In a vacuum there are no particles so sound cannot travel.
      • Alternating areas of high and low pressure in the air (compressions and rarefactions)
    • Sound Waves
      • Sound waves move out in ALL directions from a vibrating object.
      • Because sound waves need particles to be transmitted they are mechanical waves
      • ALL sound is carried through matter as sound waves. In a vacuum there are no particles so sound cannot travel.
      • Alternating areas of high and low pressure in the air (compressions and rarefactions)
    • Compression Where particles are pressed together as the sound wave moves through matter.
    • Compression
      • Where particles are pressed together as the sound waves move through matter
      • For example,
        • a wave travels through the springs just like sound waves travel through the air
        • the places where the springs are close together are like compressions in the air.
      compression
      • Compressions - The close together part of the wave.
      • Rarefactions - The spread-out parts of a wave.
      • Compression Wave = Longitudinal Wave
    • Longitudinal Wave (Compression Wave) Each wave particle vibrates back and forth in the same direction of the wave.
    • Sound waves covered till now:
      • States of matter (solid, liquid, gas)
      • Speed of sound through matter
      • No sound in a vacuum
      • Vibration
      • Compression + Rarefaction
      • Longitudinal waves
      • Remember that ….
    • Waves transfer energy without moving matter. Frequency= waves/time If you watch the 3 red dots you will see them vibrate, but not move with the wave to the end.
    • Wavelength & Frequency
      • Wavelength is the distance between one part of a wave and the same part of the next wave
      • Frequency is the number of waves passing a point in a certain tme
      • Many waves = high frequency
      • Few waves = low frequency
    • Pitch = Frequency
      • How high or low a sound is
      • Pitch depends on the frequency of a sound wave
      • For example,
      • Low pitch
      • Low frequency
      • Longer wavelength
      • High pitch
      • High frequency
      • Shorter wavelength
    • Frequency is measured in Hertz
      • For example:
      • If 20 waves are made per second, then the frequency is 20 cycles per second =
      • 20 Hertz
      • Hz
    • 20 Hz – 20,000 Hz The human ear can only hear sounds between 20Hz and 20,000 Hz (Frequency/Pitch) Below 20 Hz is called infrasound Above 20,000 Hz is called ultrasound
    • Ultrasound sound waves with frequencies above the normal human range of hearing. Sounds in the range from 20,000-100,000Hz Infrasound sounds waves with frequencies below the normal human range of hearing. Sounds in the 0.001 - 20Hz range
    • The Ear
      • Sounds reach our ears through vibrating air particles
      • Our ears capture sound waves and turn them into signals that go to our brains
      • Sound waves move through 3 parts of the ear; outer ear , middle ear , + inner ear
    • The Human Ear
    • Amplitude is the maximum distance the particles in a wave vibrate from their rest positions.
    • Amplitude = loudness
      • The intensity of a sound decreases as you move away from a sound. The sound is softer.
      • As the source of a sound comes closer the sound becomes louder, more intense
      • A loud sound has a high amplitude
      • A soft sound has low amplitude
      soft loud
    • Amplitude = loudness
      • The volume or loudness of sound is measured in decibels
      • dB
    • Loudness of Sound in Decibels Sound Loudness (dbs) Hearing Damage Average Home 40-50 Loud Music 90-100 After long exposure Rock Concert 115-120 Progressive Jet Engine 120-170 Pain
    • Sound and Instruments
      • Different musical instruments create different sound vibrations
      • Wind instruments by blowing and vibrating the air e.g. flute, saxophone, organ
      • String instruments by touching and vibrating the strings e.g. guitar, violin, piano
      • Percussion instruments by hitting a surface e.g. drums, cymbals, triangle
    • Sound and Instruments
      • Instruments can be played at different pitches (musical notes) by changing the lengths of different parts.
      • For example,
      • Another way to make different pitches is to change the thickness of the material that vibrates.
      A trombone’s mute absorbs some of the sound waves produced, so a different sound is made.
    • Sonar
      • Sonar uses reflected sound waves (echoes) to find objects in water or air
      Animals use sonar or echo location to find their prey (food); these sounds have such a high pitch or frequency that the human ear cannot hear them Humans use sonar to locate or find objects
    • Ultrasound (above 20,000 Hz) Ultrasound waves are used in medicine They are also reflected sound waves
    • Other types of waves
      • Remember sound waves are longitudinal and mechanical
      • Other waves are transverse, electromagnetic and water waves
    • Transverse waves wave particles vibrate in an up-and-down motion.
    • Transverse waves
      • Crests - Highest part of a wave
      • Troughs - The low points of the wave
    • Electromagnetic waves
      • Electromagnetic waves travel as transverse waves
      • Electromagnetic waves CAN travel through a vacuum
      • Light, microwaves, x-rays, and TV and radio transmissions are all examples of electromagnetic waves
    • Water Waves
      • The blue surface particles move in a clock-wise direction
    • Wave concepts covered in this power point:
      • Sound Waves
      • States of matter (solid, liquid, gas)
      • Speed of sound through matter
      • No sound in a vacuum
      • Vibration
      • Compression + Rarefaction
      • Longitudinal waves
      • Wavelength
      • Frequency = Pitch
      • Hertz Hz
      • 20 – 20,000 Hz
      • Ear ( outer, middle, inner ear)
      • Amplitude = Loudness = Volume
      • Decibels dB
      • Sonar
      • Ultrasound, infrasound
      • Other waves
      • Transverse waves
      • Crests
      • Troughs
      • Electromagnetic waves
      • Water waves
    • That’s all folks!