Chapter 1_ Introduction to Physics_1_

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Chapter 1_ Introduction to Physics_1_ Powered By Docstoc
					Chapter 1: Introduction to

    1.1 Understanding Physics
1.1 Understanding Physics

   1. Like all sciences, physics is based on experimental
    observations and quantitative measurements.
1.1 Understanding Physics

   2. Historically, until nineteenth century,
    physics was called natural philosophy.
1.1 Understanding Physics

   3. Physics is a branch of science concerning
    study of natural phenomena, that is, properties
    of matter and energy.
1.1 Understanding Physics

   4. Some examples of natural phenomena
   (a) sunrise and sunset,
   (b) lightning and thunder,
   (c) rainbow and blue sky,
   (d) earthquake and tsunami.
Field of study in Physics

   1 In general, physics is concerned with the
    study of energy and the properties and
    structure of matter.
Field of study in Physics

   2 The fields of study in physics can be
    divided into classical physics and modern
Field of study in Physics

   3 Classical physics deals with questions regarding
    motion and energy. It includes five important areas:
    mechanics (forces and motion), heat, sound, electricity
    and magnetism, and light.
Field of study in Physics

   4 Modern physics concentrates on scientific
    beliefs about the basic structure of the material
    world. Its major fields include atomic, molecular
    and electron physics, nuclear physics, particle
    physics, relativity, origin of the universe, and
Chapter 1

   1.1.2 Understanding Base Quantities
   and rived Quantities
Base Quantities

   1. Physical quantities are quantities that
    can be measured.
Base Quantities

   2. A physical quantity can be represented by a symbol of
    the quantity, a numerical value for the magnitude of the
    quantity and the unit of measurement of the quantity.

                       Length, l = 1.67 m

          l - symbol    1.67is the value    m - unit
Base Quantities
   3. Base quantities are physical quantities
    that cannot be defined in terms of other

    Base quantity :   Derived quantity :
    Length            Area = length x length
Base Quantities
   4. Table 1.1 shows five base quantities and
    their respective SI units.
Base Quantities
        Base quantities            SI base units

    Name           Symbol      Name           Symbol

    Length                l    Metre               m

     Mass             m       Kilogram             Kg

     Time                 t   Second               s

    Electric              I   Ampere               A
  Temperature         T        Kelvin              K
Derived Quantities
   1 Derived quantities are physical quantities derived
    from base quantities by multiplication or division or both.
    The unit for a derived quantity is known as a derived unit.
Derived Quantities

   2 Table 1.2 shows some examples of derived quantities
    and their corresponding derived units. Several derived
    units are complex. Special names are substituted for these
    units. For example, the unit for the derived quantity, force,
    is the newton (N).
Derived Quantities
Derived quantities                       Derived units

Area = Length x breadth            [Area] = m x m = m2

Velocity = Displacement            [Velocity] =
               Time taken          = ms–1         s
Acceleration=                       [Acceleration] = ms
              Change in velocity
                 Time taken         = ms–2            s

Density = Mass                     [Density] = kg = kgm–3
Scientific Notation
   1 Scientists have developed a shorter method of
    expressing very large or very small numbers. This method
    is called scientific notation or standard form.

    Distance from house to school : 5 000 m
Scientific Notation
   2 Scientific notation is based on powers of the
    base number 10. The scientific notation in
    standard form is written as:
                            A x 10n
   where
   (a) 1  A < 10 and A can be an integer or decimal number.
   (b) n is a positive integer for a number greater than one or
    a negative integer for a number less than one.
   1. Prefixes are used to simplify the
    description of physical quantities that are
    either very big or very small.

   2. It is not easy to figure out a distance of
    100 000 mm. Neither it is easy to imagine
    the size of an atom which has a radius of
    0.0000005 m.

   3. Table 1.3 lists some commonly used SI prefixes.

Ram : 512 Mb                     HD : 80 Gb
   Prefix    Symbols   Power/factor          Value

    Giga-      G           109        1 000 000 000

   Mega-       M           106        1 000 000

    Kilo-       k          103        1 000

    Deci-       d          10-1       0.1

   Centi-       c          10-2       0.01

    Milli-     m           10-3       0.001

   Micro-      μ           10-6       0.000 001

   Nano-        n          10-9       0.000 000 001

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