sound and space in pyhsics

• Sound waves are longitudinal waves that require a medium such as gases, liquids or solids to travel through.
• In science a wave is an oscillation or

  vibration that transfers energy or

  information.

  A wave can also be an undulation on the

  surface of water.

  Matter does not get transferred.

  Waves have many uses, for example,

  microwaves cook food, and sound waves

  help you communicate.
• Transverse waves:

  • The wave travels away from the source
  • The direction of the wave is at right angles to the movement of the source
  • In a transverse wave, the coils do not travel horizontally, each coil of the Slinky just vibrates up and down
  • Examples include: water waves, electromagnetic waves, light waves, Mexican waves
• Longitudinal waves:

  • The wave travels away from the source
  • The direction of the wave is parallel to the movement of the source
  • In a longitudinal wave, the coils do not travel horizontally, each coil of the Slinky just vibrates left and right
  • Examples include: sound waves, ultrasound waves
• Compression

  The wavelengths are close together.

  Rarefaction

  The wavelengths are spread apart.

  When waves bounce off a surface

  we call this reflection.

  The waving coming into the barrier

  (object) is called the incident

  wave.

  The wave coming out of the

  barrier is called the reflected

  wave.
• Superposition (superpose) is seen when two waves of the same type

  are put together. One of two things will happen:

  If the waves are in step they

  will add up and you get more

  than you had before.

  If the waves are not in step

  they cancel each other out

  and you get less than you had

  before.
• Sound waves can reflect off of surfaces. When sound reflects off a

  surface this is called an echo. Sometimes echoes are clear repeats of

  a sound like when you call “Hello” into a deep cave and hear “hello…

  hello…” repeated back. Most echoes are not this clear though.

  Sound takes time to travel, so there is a time delay between making a

  sound and hearing the echo. Since we know the speed of sound in air

  (340 m/s) we can use echoes as a way of measuring distance. Some

  animals can do this too, for example; bats use echoes to help them hunt.
• When sound waves echo, it can result in lots of echoes joining together to

  produce a longer sound; called reverberation. Reverberations are a nuisance

  in cinemas and theatres because they make it difficult to hear the show.

  Putting soft covers on the walls and carpets on the floors can reduce echoes.

  Ultrasound echoes are useful. Hospitals can use them to

  make images of things inside the body like unborn

  babies, cancerous tumours and injuries. They can also be

  used on ships to measure the depth of the water and to

  locate shoals of fish.
• In science, a wave is an oscillation or vibration that transfers energy or information
• A wave can also be an undulation on the surface of water
• Waves do not transfer matter
• Examples of waves include microwaves for cooking food and sound waves for communication
• Features of a wave:

  • Peak: top of a wave
  • Trough: bottom of a wave
  • Frequency: the number of waves passing a point each second
  • Amplitude: the distance between the origin and a peak/trough
  • Wavelength: the distance of one whole wave (between 2 peaks/troughs)
• Transverse Waves:

  • Wave travels away from the source
  • Direction of the wave is at right angles to the movement of the source
  • Coils vibrate up and down
  • Examples include water waves, electromagnetic waves, light waves, Mexican waves
• Longitudinal Waves:

  • Wave travels away from the source
  • Direction of the wave is parallel to the movement of the source
  • Coils vibrate left and right
  • Examples include sound waves, ultrasound waves
• Compression: wavelengths are close together

  • Rarefaction: wavelengths are spread apart
• Superposition:

  • Two waves of the same type put together can either add up if in step or cancel out if not in step