Chapter 3 Rules and Key Points Exponents Scientific Notation Prefixes Metric Conversion Velocity Weight

Exponents Rule 3 ‑ 1: If we make the exponent more positive, the decimal point moves to the left. Rule 3 ‑ 2: If the exponent is made more negative, the decimal point moves to the right = 670 X 10 = 67.0 X 10 2 = 6.70 X = X 10 ‑ 1 = X = 2.75 X 10 ‑ 3

Scientific Notation Key Point: Expressing numbers as numbers between 1 and 10 times the proper power of ten is called scientific notation. Expressing numbers as numbers times powers of ten that are multiples of 3 is called engineering notation. 47,000 = 4.70 X 10 4 in scientific notation to three places. 47,000 = 47.0 X 10 3 in engineering notation to three places.

Prefixes Rule 3 ‑ 3: To change numbers with prefixes to regular numbers, replace the prefix with the power of ten that it represents and then change to a regular number. 30 mA = 30 X 10 ‑ 3 A = A 33 k  = 33 X 10 3  = 33,000 

Metric Conversion Some conversions of linear measure between English and metric are: 1 in = 2.54 cm 1 cm = in 1 yd = m 1 m = yd 1 mi = km 1 km = mi 20 cm = in 12 in = cm 100 m = yd 5 mi = km

Velocity The units of velocity are meters/second or kilometers/hour in metric feet/second or miles/hour in English. 15 m/s = ft/s

Weight Common units of weight in metric are the milligram, gram, and kilogram. In the English system, we have the ounce, pound, and ton. 16 oz = 1 lb 1 kg = oz 2000 lb = 1 ton 1 lb = gm 100 lb = kg 100 kg = lb