Physical Quantities

• SI base units

  • mass- kilograms
  • length- meters
  • time- seconds
  • temperature- kelvin
  • current- ampere
  • amount of substance- mole
  • luminous intensity- candela
• Scalar quantity has only a magnitude
• Vector quantities have both magnitude and direction
• Accuracy is how close the measured value is to the true value of the quantity being measured.
• Precision is how close the measured values are to each other
• Zero error is a type of systematic error which occurs when an instrument gives a reading when the reading is supposed to be zero
• Random errors are unpredictable fluctuations in a reading as a result of uncontrollable factors such as human error, environmental conditions
• Systematic errors arise from the use of faulty instruments or flaws in the experiment
• Absolute uncertainty is where the uncertainty is given as a fixed quanitity
• Percentage uncertainty is where the uncertainty is given as the percentage of the measurement
• Relative uncertainty is where the uncertainty is given as a fraction of the measurement
• Average value = (sum of all readings) / number of readings
• Prefixes

  • pico- 10^-12
  • nano- 10^-9
  • micro- 10^-6
  • milli- 10^-3
  • centi- 10^-2
  • deci- 10^-1
  • kilo- 10^3
  • mega- 10^6
  • giga- 10^9
  • tera- 10^12