Factor Label Method Factor Label Method used to
Factor Label Method
Factor Label Method used to convert from one unit to another by multiplying the original measurement by fractions that are equal to one. Examples of fractions that are equal to one : 1 kg 1000 g 1 00 cm 1 m 1 in 2. 54 cm 1 hr 3600 sec When a measurement is multiplied by one of these fractions the units will cancel and the number will change but the quantity is still the same.
Example 1: Equivalent Fraction: Convert 80 mm to m 80 mm 1 1 m x 1000 mm = 1 m 80 m = 1000 = 0. 08 m or = 8 x 10 -2 m
Example 2 Find the number of kilometers in 5. 00 miles. Given: 1 mi = 1. 609 km 5. 00 mi x 1 1. 609 km 5. 00 x 1. 609 km 1 mi = = 8. 05 km
Multi-step conversions Example 3 7. 80 km = ? ft First find the equivalent relationships to get from km to feet. 1 mi = 5280 ft 1 mi= 1. 609 km 7. 80 km 1 1 x mi 1. 609 km 7. 80 x 1 x 5280 ft = 1 x 1. 609 x 1 x 5280 1 41 184 ft 1. 609 ft = mi = 25 600 ft
Example 4 Converting compound units. 65 mi/h = ? ft/s 5280 ft = 1 mi Separate the 1 st compound unit Convert the mi to ft Convert h to s 65 mi 1 h x 5280 ft 1 mi 65 x 5280 x 1 ft 3600 s x 1 h 3600 s 343 200 ft = 3600 s = = 95 ft/s
A few tips The units you want to get rid of must cancel out (one on top and one on the bottom) Make sure the top of your conversion factor is equal to the bottom Use the right units with the right numbers – remember that any conversion factor can be flipped upside down if needed Always show your work!
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