Acoustics

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Is the distance that the waves travel in unit time (m/s). The different waves travel at different speeds, the waves on the sea are slow compared to the speed of sound, the sound travel 330 meters every second but even that's not as fast as radio waves, they travel at the speed of light. =====

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Is the distance between matching points on the wave (m); The distance between one peak or crest of a wave of light, heat, or other energy and the next corresponding peak or crest. For example, when you move something slowly there is a large wavelength, when you move something quickly there is a small wavelength. =====

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Is the vibration parallel to direction of travel of wave. Longitudinal waves travel in the direction of the length; running lengthwise. =====