CHAPTER 1: Physical quantities and measurements 5 Hours

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CHAPTER 1Physical quantities and
measurements(5 Hours)
www.kmph.matrik.edu.my/physics
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1.1 Physical Quantities and Units

• Physical quantity is defined as a quantity which
  can be measured.
• It can be categorised into 2 types
• Basic (base) quantity
• Derived quantity
• Basic quantity is defined as a quantity which
  cannot be derived from any physical quantities.
• Table 1.1 shows all the basic (base) quantities.

Table 1.1
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• Derived quantity is defined as a quantity which
  can be expressed in term of base quantity.
• Table 1.2 shows some examples of derived quantity.

Table 1.2
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• Unit is defined as a standard size of measurement
  of physical quantities.
• Examples
• 1 second is defined as the time required for
  9,192,631,770 vibrations of radiation emitted by
  a caesium-133 atom.
• 1 kilogram is defined as the mass of a
  platinum-iridium cylinder kept at International
  Bureau of Weights and Measures Paris.
• 1 meter is defined as the length of the path
  travelled by light in vacuum during a time
  interval of

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• The unit of basic quantity is called base unit
• addition unit for base unit
• unit of plane angle - radian (rd)
• unit of solid angle- steradian (sr)
• The common system of units used today are S.I
  unit (System International/metric system) and cgs
  unit - UK.
• The unit of derived quantity called derived unit

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1.1.1 Unit Prefixes

• It is used for presenting larger and smaller
  values.
• Table 1.3 shows all the unit prefixes.
• Examples
• 2700000 m 2700 km 2.7 Mm
• 0.00000476 s 4.76 x 10-6 s 4.76 ?s

Table 1.3