Chapter 1: Measurement and the Scientific Method

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Chapter 1 Measurement and the Scientific Method

• Nave and Nave
• pages 1-6

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Experimentation

• Scientists assume that nature acts in an orderly
  and reproducible manner
• A controlled experiment should carried out many
  times should yield similar results
• Example Galileo discovered that all objects
  dropped near the earths surface fall at the same
  rate if air resistance is neglected
• Falling objects are much simpler systems than the
  human body, but understanding the simple physical
  laws is tantamount to understanding complex
  systems

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Measurements

• Scientists must use the same units of measurement
  to convey their results to each other
• There are three fundamental mechanical units used
  by scientists
• All other mechanical quantities are expressed in
  units derived from these fundamental units

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Accuracy Significant Figures

• Each measurement that is made is not exact and
  has some amount of uncertainty
• If a meterstick is used to measure the dimensions
  of your book, then you obtain the values listed
  in the table below
• Identical uncertainties were obtained because the
  same measuring device was used for all
  measurements
• The precision of a measurement is determined by
  the measuring device

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Accuracy Significant Figures...

• When mathematical operations are carried out on
  measurements with uncertainties, the result can
  be no more accurate than the least accurate
  measurement
• Example If the length and width of an object are
  8.50 /- 0.01 inches and 11.0 /- 0.1 inches,
  then the area of the object would be 93.5 /- 0.1
  inches NOT 93.5 /- 0.01 inches.
• Develop good habits and always include an
  uncertainty with each measurement

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Scientific Notation

• You will encounter very large and small numbers
  in science that can be easily expressed using
  scientific notation
• Scientific notation uses powers of 10 to
  facilitate mathematics using extremely large and
  small numbers
• 10x10 100 102 10-1x10-1 10-2
• 1000 103 0.001 10-3
• 300,000,000 3x108 0.000000628 6.28x10-7

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Unit Conversions

• Familiarize yourself with unit conversions
• Any conversion can be accomplished if you
  understand how to set up a conversion
• Example Convert 6 ft 2 inches to meters.
• 1 m 3.28 ft
• 1 ft 12 inches

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Suggested Exercises

• Do problems 1, 2, 3, 4, 6, 8, 9, 10