Significant Figures in Reading Measurements and Metric Measurements Lab

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Significant Figures in Reading Measurements and
Metric Measurements Lab
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Making Measurements
How do I read this?!?!
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Making Measurements

• Read the measurement to the smallest subdivision
  of your instrument (Subdivision the distance
  between two of the smallest lines)
• Estimate one more digit

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Making Measurements

• Each subdivision represents a certain
  measurement.
• Example The paper is at least ______ but no more
  than ______ .

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Making Measurements
1. Smallest Subdivision?
15 mm
3. It is at least______ but no more than______.
16 mm
millimeters
2. How many mm?
4. How many mm?
15.5 mm
about 15 mm
estimated digit
5. How many cm?
1.55 cm
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Uncertainty in Measurements

• Work in pairs (or groups of three)
• Using the meter stick, measure the width of your
  paper in meters (one persons paper).
• Measure it using each side of the meter stick and
  write down your measurements.

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Uncertainty in Measurements

• Which side of the meter stick gave you the best
  measurement?
• Why is it the best measurement?

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Precision in Measurements

• The millimeter side of the meter stick has the
  greatest precision because it has the most
  subdivisions and thus gives you the measurement
  with the MOST certain digits.

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Significant Figures

• Definition
• All of the digits that are CERTAIN plus a last
  digit that is estimated.
• How many significant figures are in each of the
  measurements you made using the 4-sided meter
  stick?
• 1m side? cm side?
• dm side? mm side?

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Nature of Measurements
Measurement - quantitative observation consisting
of 2 parts
Part 1 - number Part 2 - scale (unit)
Examples 20 grams 6.63 x 10-34 Joule seconds
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The Fundamental SI Units(le Systéme
International, SI)
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SI PrefixesCommon to Chemistry
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Metric Measurement Lab

• We are going to go into lab and practice making
  measurements.
• Pick the units you want to measure each item in
  as a group. For example, you will be measuring
  the length of the classroom and you can pick to
  measure it in either m, cm, mm, or km.
• Just remember to measure to the smallest
  subdivision and estimate one digit!!