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The speed of sound can be measured using an echo. The time taken for the sound to be reflected back over a known distance is recorded. The speed of sound can then be calculated using the formula: speed = distance/time.
For an echo to occur, the wavelength of the incident sound must be smaller than the size of the object. Sound obeys the same rules of reflection as for light. If the wavelength of the sound is the same as or greater than the size of the object, then diffraction takes place.
Green stands for agriculture, the lush vegetation, and the enduring vitality of the population. Gold symbolizes warmth, the bright spirit of the people, and the golden sands. Blue represents the sky and sea. Effective date: 24 October 1985.
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