Measurements

• Physical quantity

  Anything that can be measured with a measuring instrument
• Accuracy

  Making sure that any measurement taken is as close as possible to it's correct value.
• Precision

  When a measurement is taken more than once, it should be the same or close in value each time repeated.
• SI units stand for?

  International System of Units
• SI units definition?

  Used by scientists to make sure that measurements are carried out the same way and can be understood by everyone.
• Standard unit for: Time

  Seconds (s)

  Stopwatches and timers
• Standard unit for length:

  Metre (m)

  When measuring something shorter or longer than a metre, the following units are used:

  • Millimetre (mm)
  • Centimetre (cm)
  • Kilometre (km)
• Trundle wheel

  Is used to measure long curved lengths, e.g a running track
• Opisometer


  Looks like a mini Trundle wheel and is used to measure short, curved lengths, e.g lines on a map
• Digital caliper


  Used to measure small, curved objects, e.g. the diameter of pipes or coins
• Area


  The amount of space a two-dimensional shape takes up
• Volume 


  The amount of space and object takes up
• Graduated cylinder


  The piece of laboratory equipment used to measure the volume of a liquid
• Meniscus


  The name of the curve in the top surface, always read the bottom of the meniscus at eye level to ensure accurate reading
• Mass


  The amount of matter in an object
• Mass balance and spring balance


  Instruments used to measure mass
• Temperature


  The measurement of the hotness or coldness of an object or body.
• Thermometer 


  The instrument used to measure temperature
• Types of thermometers (most common)

  • Alcohol in glass
  • Digital
• Error


  Is a mistake that is introduced into a reading it an investigation
• Blunder


  Mistake caused by carelessness,

  e.g spilling liquid before measuring it.
• Systematic error


  Due to a problem with the measuring instrument or environment, e.g a metre stick that's worn down at the end
• Random error 


  A mistake made by the person taking the measurement, e.g reading a scale incorrectly