Measurement

• Rulers can be used to measure small distances of a few centimetres (cm)
• Rulers are able to measure to the nearest millimetre (mm)
• Measuring with a ruler


  • Use a ruler to measure small distances to the nearest mm
• Measuring larger distances


  • Use a tape measure for a few metres or a trundle wheel for even larger distances
• Trundle wheel


  • Can be used to measure large distances
• Measuring cylinders


  • Can be used to measure the volume of liquids
  • Can be used to find the volume of an irregular shape by measuring the change in volume
• Measuring time


  • Stop-clocks and stopwatches can be used
  • Human reaction time can have a significant impact on very short time measurements (less than a second)
• Multiple readings


  • Measuring small quantities accurately by taking multiple readings and averaging
  • Examples: thickness of paper, time period of a pendulum
• Scalar


  Quantity with only magnitude
• Vector


  Quantity with both magnitude and direction
• Examples of scalars and vectors

  • Scalars: distance, speed, mass, time, energy, volume, density, pressure, electric charge, temperature
  • Vectors: displacement, velocity, acceleration, force, weight, momentum, electric field strength, gravitational field strength
• Calculating with vectors


  • Vectors represented by arrows
  • Component vectors drawn with dotted lines and subscripts
  • Calculating vectors graphically: choose scale, draw vectors at right angles, complete rectangle, draw resultant
  • Calculating vectors by calculation: use Pythagoras' Theorem and trigonometry