Accuracy, Precision, and Significant Figures in Measurement

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Presentation transcript:

Accuracy, Precision, and Significant Figures in Measurement Accuracy is how close to the true value a given measurement is. Precision is how well a number of independent measurements agree with one another.

Accuracy, Precision, and Significant Figures in Measurement Significant Figures are the total number of digits in the measurement. The results of calculations are only as reliable as the least precise measurement. Rules exist to govern the use of significant figures after the measurements have been made.

Mass of a Tennis Ball Figure: Table 01-06-01UN Title: Caption:

Accuracy, Precision, and Significant Figures in Measurement Rules for Significant Figures: Zeros in the middle of a number are significant Zeros at the beginning of a number are not significant Zeros at the end of a number and following a period are significant Zeros at the end of a number and before a period may or may not be significant.

Accuracy, Precision, and Significant Figures in Measurement Rules for Rounding Numbers: If the first digit removed is less than 5 - round down If the first digit removed is greater than 5 - round up If the first digit removed is 5 and following numbers are nonzero - round up If the first digit removed is 5 and following numbers are zero - round down

Accuracy, Precision, and Significant Figures in Measurement How many significant figures does each of the following measurements have? (a) 0.036653 m (b) 7.2100 x 10–3 g (c) 72,100 km (d) $25.03

Accuracy, Precision, and Significant Figures in Measurement How many significant figures does each of the following measurements have? (a) 0.036653 m (5) (b) 7.2100 x 10–3 g (5) (c) 72,100 km (3 or 4 or 5) (d) $25.03 (exact)

Accuracy, Precision, and Significant Figures in Measurement Round off each of the following measurements. (a) 3.774499 L to four significant figures (b) 255.0974 K to three significant figures (c) 55.265 kg to four significant figures

Accuracy, Precision, and Significant Figures in Measurement Round off each of the following measurements. (a) 3.774 L (b) 255 K (c) 55.26 kg

Accuracy, Precision, and Significant Figures in Measurement Rules for Calculating Numbers: During multiplication or division, the answer can’t have more sig figs than any of the original numbers. During addition or subtraction, the answer can’t have more digits to the right of the decimal point than any of the original numbers.

Significant Figures in Calculations

Significant Figures in Calculations

Significant Figure Calculations Ok, now… Try These!