Science involves measurement

• • To describe physical phenomena, scientists make measurements of various aspects of nature
  • Measurements are made using scientific apparatus
  • As simple as a ruler
  • As complex as an electron microscope
• Each measurement is associated with a physical quanitity

  • E.g. a ruler measures length
  • E.g. a stopwatch measures time
• Each measurement is done in terms of a unit

  • E.g. Typical ruler measures in cm
  • In USA, typical ruler measures in inches
  • Both are measuring the same physical quantity
• The laws of physical science are expressed as mathematical relationships between physical quantities