measurements

• 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
• 10^-16 radius of a hydrogen nucleus

  10^-10 size of typical atom

  10^-4 average width of a human hair

  10^-3 diameter of a wire

  10^-1 length of a pair of chopsticks

  10^2 length of a football field

  10^3 height of Mount Everest

  10^6 radius of earth

  10^15 distance travelled by light in a year

  10^22 distance from earth to andromeda galaxy
• measuring tape: zero to several metres, 0.01cm or 0.1mm

  metre rule: zero to one metre, 0.01cm or 0.1mm

  digital calipers: zero to 15cm, 0.001cm or 0.01mm

  digital micrometre screw gauge: zero to 2.5cm, 0.0001cm or 0.001mm
• • period of pendulum varies by the length of pendulum
  • pendulum depends on; gravitational field strength, length of pendulum
  • human reaction time is about 0.3-0.5s
  • stopwatch precision of 0.01s
• scalar: magnitude only

  eg. distance, speed, mass, time, energy

  vector: magnitude and direction

  eg. displacement, velocity, weight, force, acceleration
• speed = distance/time taken (m/s)

  velocity = displacement/time taken (m/s)

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  velocity is rate of change of displacement