The metric system has units in powers of ten for ease in computations

The metric system has units in powers of ten for ease in computations

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The metric system has units in powers of ten for ease in computations, with prefixes nano = 10 -9 = 1/1,000,000,000, as in nanometers (nm). The speed of light is 1 foot per nanosecond. micro = 10 -6 = 1/1,000,000, abbreviated µ. A micrometer is often called simply a micron. milli = 10 -3 = 1/1,000. Used everywhere: millimeters (mm), milligrams (mg), milliseconds. centi = 10 -2 = 1/100. Mostly important for centimeters (cm). 1 inch is exactly 2.54 cm. kilo = 10 3 = 1,000. One kilometer (km) = 5/8 mile. Time in hours, years, not kiloseconds. mega = 10 6 = 1,000,000. Mostly used for MB, megabytes. Megameters and Megagrams never caught on. Angular Measure is used to measure arc lengths in the sky. A circle has 360° (degress). The distance between the pointers of the Big Dipper is about 5°. The angle is formed by drawing a line from the star to your eye to the other star,
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Unformatted text preview: • but the best way to think of it is like a flat ruler placed on the sky. • One degree = 60' (minutes). The sun's or moon's diameter is about 30', or 1/2°. • One minute = 60" (seconds). One second is the smallest separation visible in most telescopes. Angular Measure is also used to measure arc lengths on the spherical earth. • 1° is the north-south length of the corner missing from the otherwise rectangular shape of Utah. • 1' of latitude is one nautical mile (a little more than a usual mile). • 1" of latitude is almost exactly 100 feet. • Note that angles of longitude are less than latitude because longitudinal lines get closer together as one approaches the poles. For example, Utah is 5° high and 5° wide, but it doesn't look square....
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