Measurement Units, Conversion Factors, and Precision in Science

Measurement

comparison between quantity and known standard (unit)

1 in

2.54 cm

1 km

0.6 mi

1 kg

2.2 lbs

1 qt

0.946 L

1 min

60 s

1 hr

60 min

1 day

24 hr

1 week

7 days

1 yr

12 mo

1 mi

5280 ft

1 decade

10 yrs

1 century

100 yrs

1 millennium

1,000 yrs

1 ft

12 in

1 yd

3 ft

1 gal

4 qt

1 qt

2 pt

1 pt

16 fl oz, 2 cups

1 cup

8 fl oz

1 lbs

16 oz

1 T (tablespoon)

3 t (teaspoons)

1 ton

2,000 lbs

dimensional analysis/factor label method

making unit conversions based on math principles of fractions

conversion factor

equivalent relationship between different units

Adding/subtracting Sig Figs

Round to the least number of sig figs in problem, accounting for periods————as certain as least certain measurement

multiplying/dividing

Only contain as many sig figs as measurement with least amount of sig figs

precision

the reproducibility of a measurement

Accuracy

how close a measurement is to the true value