Measurement

Measurement

physical quantity
1. quantity that can be measured
2. numerical magnitude & a unit
  1. SI units
    1. prefixes
      1. 10^9 (G, giga-)
      2. 10^6 (M, mega-)
      3. 10^3 (k, kilo-)
      4. 10^-1 (d, deci-)
      5. 10^-2 (c, centi-)
      6. 10^-3 (m, milli-)
      7. 10^-6 (micro-)
      8. 10^-9 (n, nano-)
3. 7 base quantities
  1. #mass
    1. kilogram (kg)
  2. #time
    1. second (s)
    2. stopwatches
      1. precision to 0.1s
    3. pendulum
      1. period
        time taken for one complete oscillation
        swing from one end to the other and back again to starting position
      2. oscillation
        each complete to-and-fro motion
    4. human reaction time
  3. #electric current
    1. ampere (A)
  4. #temperature
    1. kelvin (K)
  5. luminous intensity
    1. candela (cd)
  6. amount of substance
    1. mole (mol)
  7. #length
    1. metre (m)
    2. metre rule
      1. avoid parallax errors
      2. precision to 0.1cm; length of a book
    3. vernier calipers
      1. main scale & sliding vernier scale
      2. check for zero error
        positive/ negative
      3. how to read?
        1. grip object gently using outside jaws of calipers
        2. read main scale opp. zero mark on vernier scale
        3. find the mark which coincides with a marking on main scale
        4. find diameter by adding main scale reading to vernier scale reading
      4. precision to 0.01cm; diameter of a test-tube
    4. micrometer screw gauge
      1. how to read?
        1. turn thimble until the anvil and spindle gently grip the object, turn until ratchet clicks
        2. read main scale reading at edge of thimble
        3. thimble scale has 50 divisions, each is 0.01mm. take thimble reading opposite datum line of main scale
        4. find diameter by adding main scale reading to thimble reading
      2. precision to 0.01mm; wires
      3. check for zero error
        positive/ negative
    5. tape measure
      1. precision to 0.1cm; a person's waist
4. derived quantities
  1. area
    1. length*width (m^2)
  2. volume
    1. length*width*height (m^3)
  3. speed
    1. length/time (ms^-1)

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	Creado por Syifa hace casi 11 años