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Title
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Wave Movement
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Type
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Primary: Mission Briefing Article
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Operation
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Infinite Potential
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Mission:
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Mission 2: Waves of Change
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Print Page
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33,34
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Subjects
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Physical science | Energy | Science
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Grades
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5 | 6 | 7 | 8
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Keywords
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wave, mechanical, compression, vibrate, direction, squeeze, squash, stretch, compression, rarefaction, sound wave, transverse, right angle, perpendicular, direction, electromagnetic, crest, trough, amplitude, wavelength, frequency
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Duration
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00:15:00 (HH:MM:SS)
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Audience
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Teachers | Elementary Grades | Junior High
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Created On
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3/30/2009
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Copyright
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Speaker and Spring toy photos: Wikimedia Commons; Team Highlight photo: Whitney Caldwell, The JASON Project
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From: Infinite Potential Mission 2: Waves of Change (pp: 33,34) |
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Wave Movement Mechanical waves can be divided into compression and transverse waves. How do these waves move and what affects their movement? Learn more in this article. |
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|  |  | | | The speed of sound waves depends on the medium and temperature. These waves travel faster through solids, whose particles are closer together, compared with liquids and gases, whose molecules are farther apart. For example, sound travels around 12,000 m/s (39,000 ft/s) through diamond (a solid) and only 343 m/s (1,130 ft/s) through air (a gas).
In addition to the type of medium, the speed of a compression wave depends upon temperature. For example, sound travels around 331 m/s (1,090 ft/s) through air at 0ºC (32ºF) and increases to 343 m/s (1,130 ft/s) through air at 20ºC (68ºF). | |  | |  | When energy moves in waves, it can be observed as either compression waves or transverse waves. Compression Waves
Compression waves vibrate the medium back and forth in the same direction that the wave travels. You can make a compression wave by squeezing together and releasing several coils of a stretched spring. Repeat this process and you will notice that some areas become squashed together while other areas get stretched out. The areas that are squashed together are called compressions. On either side of the compressions, the spring coil is being stretched. These areas are called rarefactions. Sound waves move as compression waves. Hold your hand in front of a speaker playing music and you can feel these compression waves. When a speaker moves in and out, it transfers kinetic energy to the air particles next to it. The speaker’s movement pushes and pulls the air particles, creating compressions and rarefactions in the air. Compression waves, such as sound waves, can use solids, liquids, or gases as a medium. However, the speed of the wave is affected by the medium it is traveling within. Transverse Waves
Transverse waves move at right angles, or perpendicularly, to the direction the energy travels. You can see transverse waves when you shake one end of a jump rope from side to side or up and down. While the energy moves along the rope from end to end, the disturbance that created the wave moves at right angles to the direction of the energy. Electromagnetic waves are also examples of transverse waves. Describing Waves
Observe waves at the beach and you will notice the basic parts of a wave. The water waves you can see are transverse waves, which have a distinct crest and trough. Crests are the high points of the wave, and troughs are the low points between crests. The height of each crest or the depth of each trough from the center is called the amplitude. In a compression wave, the compressions are similar to the crests of a transverse wave and rarefactions are similar to the troughs. The amplitude of a compression wave is measured by the density of the medium at its greatest compression. The distance from crest to crest or trough to trough in a transverse wave is called the wavelength. In a compression wave, wavelength is measured from compression to compression or rarefaction to rarefaction. Suppose you stood in the water and counted the number of wave crests that passed by you in a given amount of time. This count would tell you the frequency of these waves. In a compression wave, this frequency would be measured by determining the number of compressions over time.  
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