Unit Conversions • Conversion Factors: a ratio of equal measurements
Unit Conversions So… how many meters are in… - 1 km? 1000 m - 1 Mm? 1, 000 m (106 m) - 1 Gm? 1, 000, 000 m (109 m) How many cg are in 1 gram? 100 g How many mg are in 1 g? 1000 mg How many μg are in 1 g? 1, 000 μg (106 μg) How many ng are in 1 g? 1, 000, 000 ng (109 ng)
Unit Conversions Conversion factors change numbers, but not actual amount 100 cm = 1 m 100 cm 1 m 1 m 100 cm 1000 m. L = 1 L 1000 m. L 1 L 1 L 1000 m. L
Dimensional Analysis • Used to change from one set of units to another Process: 1. Find goal 2. T-chart 3. Find starting point • in top left corner of T chart • set it equal to goal
Dimensional Analysis Process: 4. Use conversions to transition to goal • Identify useful conversions • conversion factors must = 1 • units must cancel, leaving desired units in answer (top right corner) 5. Solve for goal • multiply by the top • divide by the bottom
Examples How many seconds do we spend in class (1. 1 hours)? 3960 sec = 1. 1 hrs 4. 0 x 103 sec Remember: 60 min 1 hr 60 sec 1 min multiply by top divide by bottom
Examples Convert 153 cm to km 0. 00153 km = 153 cm 1 m 1 km 100 cm 1000 m 1. 53 x 10 -3 km Remember: multiply by top divide by bottom
Examples If you are going 150 km per hour, how many meters per minute are you going? 2500 m/min 2. 5 x 103 m/min = 150 km 1 hr 1000 m 1 km 1 hr 60 min