W4!5

• What are the two fundamental concepts in measurement?

  Accuracy and precision
• What is the true value in measurement?

  The correct value for the measurement based on reliable references
• What is the experimental value?

  Values obtained in experimental processes
• What are errors in measurement?

  The difference between the experimental value and the accepted value
• What are significant figures?

  Numbers that are substantial to the overall value of a certain number
• What are the rules for determining the number of significant figures?

  1. All nonzero digits are significant.
  2. Zeros between nonzero digits are significant (captive zeros).
  3. Zeros before the first nonzero digit are not significant (leading zeros).
  4. Zeros after the last nonzero digit may or may not be significant (trailing zeros).

  • If there is a decimal point, all trailing zeros are significant.
  • If there is no decimal point, trailing zeros are not significant.
• How many significant figures are in the number 1.39?

  Three significant figures
• How many significant figures are in the number 309.2?


  Four significant figures
• How many significant figures are in the number 0.327?

  Three significant figures
• How many significant figures are in the number 341.20?


  Five significant figures
• How many significant figures are in the number 50?


  One significant figure
• What is scientific notation and its rules?

  • Coefficient should contain only one figure to the left of the decimal point.
  • Measurement consists of two parts: number and unit.
• What are the two systems of measurements mentioned?

  • Metric system
  • English system
• What are the characteristics of the English system of measurement?


  • Uses more than one unit for a single property.
  • Examples:
  • Length: inch, foot, yard, mile
  • Mass/Weight: pound, ounce, grain
  • Volume: gallon, pint, fluid ounce
• What are the characteristics of the Metric system of measurement?

  • Uses only one unit for each property.
  • Uses prefixes as indicators of large or small quantities.
  • Examples:
  • Length: meter
  • Mass/Weight: gram
  • Volume: liter
• What is density and its formula?

  Density is the amount of mass present in each volume, calculated as $d =$$\frac{m}{v}$
• What are the units for density?

  g/cm³, g/mL, kg/L