What Is Sound? Video

4 The Physical Setting

  • Subchapter F
    • Motion
      • For Grades: 6-8
        • Learning Goal 2
          • Something can be "seen" when light waves emitted or reflected by it enter the eye—just as something can be "heard" when sound waves from it enter the ear.
        • Learning Goal 4
          • Vibrations in materials set up wavelike disturbances that spread away from the source. Sound and earthquake waves are examples. These and other waves move at different speeds in different materials.
      • For Grades: 9-12
        • Learning Goal 5ab
          • The observed wavelength of a wave depends upon the relative motion of the source and the observer. If either is moving toward the other, the observed wavelength is shorter; if either is moving away, the wavelength is longer.
        • Learning Goal 5c
          • Because the light seen from almost all distant galaxies has longer wavelengths than comparable light here on Earth, astronomers believe that the whole universe is expanding.
        • Learning Goal 6ab
          • Waves can superpose on one another, bend around corners, reflect off surfaces, be absorbed by materials they enter, and change direction when entering a new material. All these effects vary with wavelength.