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Learn about significant figures in measurements and how they apply to air traffic controller altitudes. Discover the rules for determining the number of significant figures in various measurements.
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Significant Figures
Significant figures – all the digits known with certainty plus one final digit which is somewhat uncertain or estimated 50,000 ft Air Traffic Controller 40,000 ft 30,000 ft 20,000 ft How far away? 10,000 ft 33,000 ft ? 40,000 ft 34,000 ft ? 30,000 ft
All nonzero digits are significant. • 1,2,3,4, . . .8,9 are significant digits in a measurement. • 0 is sometimes significant. 12.4 cm 3 sig figs 7.428 g 4 sig figs 34 km 2 sig figs
2. Zeros between nonzero digits are significant. 40.7 cm 3 sig figs 87,009 g 5 sig figs 1.034 km 4 sig figs
3. Zeros appearing in front are not significant. 0.0957 cm 3 sig figs 0.0009 g 1 sig fig
4. Zeros at the end of a number and to the right of the decimal point are significant. 85.00 cm 4 sig figs 9.0000 g 5 sig figs
5. Zeros at the end of a number and to the left of the decimal point are not significant 2000 cm 1 sig fig 2000. g 4 sig figs 34,000 ft 2 sig figs 3.40 x 104 ft 3 sig figs 4 sig figs 3.400 x 104 ft
How many significant figures in the following measurements? 28.6 g 3 sig figs There are no zeros, so all three digits are significant. 3440. cm 4 sig figs Rule 5. the decimal point at the end shows it was measured to the ones place. 910 m 2 sig figs By rule 5. Was the ones place measured? 0.04604 4 sig figs By rule 3 the first 2 digits are not significant; by rule 2, the third zero is significant. By rule 3 the first 3 digits are not significant; by rule 4, the last two zeros are significant. 4 sig figs 0.006700
When multiplying or dividing, your answer is rounded so it has the same number of significant digits as the least accurate number being multiplied (the one with the least number of sig figs) 3 s. f. 3 s. f. 3 s. f. 12.0 x 12.0 = 144 2 s. f. 2 s. f. 3 s. f. 12 x 12.0 = 140 4 s. f. 4 s. f. 4 s. f. 12.00 x 12.00 = 144.0
2 s. f. 3 s. f. 537 x 12 = 6444 = 6400 2 s. f. weakest number 2 s. f. 2 s. f. 12 / 537 = 0.022346369 = 0.022 3 s. f. 2 s. f. 2 s. f. 78 x 12.00 = 936 = 940 4 s. f. weakest number
12.7 +3.18 When adding or subtracting, your answer is rounded to the least accurate place value. ? 15.88 15.9
2.183 +144.18 ? 146.363 146.36
0.0464 +12.3 ??? 12.3464 12.3