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# Measurements and Their Uncertainty 3.1 - PowerPoint PPT Presentation

Measurements and Their Uncertainty 3.1. 3.1. 3.1. Significant Figures in Calculations. Significant Figures in Calculations How does the precision of a calculated answer compare to the precision of the measurements used to obtain it?. 3.1. Significant Figures in Calculations.

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## PowerPoint Slideshow about ' Measurements and Their Uncertainty 3.1' - camille-banks

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Significant Figures in Calculations

• Significant Figures in Calculations

• How does the precision of a calculated answer compare to the precision of the measurements used to obtain it?

Significant Figures in Calculations

• In general, a calculated answer cannot be more precise than the least precise measurement from which it was calculated.

• The calculated value must be rounded to make it consistent with the measurements from which it was calculated.

• Significant Figures in Calculations

• Rounding

• To round a number, you must first decide how many significant figures your answer should have. The answer depends on the given measurements and on the mathematical process used to arrive at the answer.

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Significant Figures in Calculations

• The answer to an addition or subtraction calculation should be rounded to the same number of decimal places (not digits) as the measurement with the least number of decimal places.

• 12.52

• 349.0

• 8.24

• 369.76

The correct number of SF’s..

Significant Figures in Calculations

• Multiplication and Division

• In calculations involving multiplication and division, you need to round the answer to the same number of significant figures as the measurement with the least number of significant figures.

• The position of the decimal point has nothing to do with the rounding process when multiplying and dividing measurements.

Number of SF’s.

• 3.1.

• 1. In which of the following expressions is the number on the left NOT equal to the number on the right?

• 0.00456  10–8 = 4.56  10–11

• 454  10–8 = 4.54  10–6

• 842.6  104 = 8.426  106

• 0.00452  106 = 4.52  109

• 2. Which set of measurements of a 2.00-g standard is the most precise?

• 2.00 g, 2.01 g, 1.98 g

• 2.10 g, 2.00 g, 2.20 g

• 2.02 g, 2.03 g, 2.04 g

• 1.50 g, 2.00 g, 2.50 g

• 3. A student reports the volume of a liquid as 0.0130 L. How many significant figures are in this measurement?

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