Mr' Perez

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Mr. Perez

• Grade 6 Science
• Science Court

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Part 3

• About how fast does the sound we hear travel
  through the air to our ears?
• Sound that we hear travels at a speed of 300
  meters per second (m/sec), which is about 700
  miles per hour (MPH)
• Does sound always travel at the same speed?
• No, sound travels at different speeds through
  different materials.

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Sound Waves Gases, Liquids, and Solids
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Part 3

• Why does it seem like you hear words at the
  moment they are spoken when you are talking in a
  room?
• It seems like you hear the words instantly
  because the distance between you and the speaker
  is short. So, there is not a noticeable delay.
• What are two examples that demonstrate that sound
  takes time to travel?
• A jet plane flying overhead is seen before it is
  heard. Fireworks explode in the sky before they
  are heard. Lightning is seen before you hear the
  thunder. A person singing in a stadium is seen
  on a tv screen, but the words are heard later.

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Part 3

• The next time Shep fired the cannon, it took the
  boom slightly less than ten seconds to reach
  town. Why might it have taken less time?
• It may have been a different temperature outside,
  or it might have been more humid. Sound travels
  through different kinds of air at different
  speeds.

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Part 3

• When Doug yells at the mountains, why does he
  hear his yell again later?
• Dougs yell travels through the air, bounces off
  of a mountain wall, and travels back to him.
  This is called an echo.