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    Scientific Measurement

     

    A Scientific measurement is a result of a scientific process or experiment, usually expressed in numbers or standard units, that you obtain by measuring something. The scientific name for material is ‘matter’. All the matter occupies space and has what is called ‘mass’. Many properties of matter are quantitative; that is, they are associated with numbers. When a number represents a measured quantity, the units of that quantity must always be specified. 

    Scientific Measurement



    To say that the length of a pencil is 17.5 for example, is meaningless. However, to say that it is 17.5 centimetres (cm) properly specifies the length. The units used for scientific measurement are those of the metric system. Matter can be measured in terms of time, length and mass.

    The metric system, which was first developed in France during the late eighteenth century, is used as the system of measurement in most countries throughout the world.

    SYSTÈME INTERNATIONAL D’UNITÉS

    In the past, many countries followed their own system of measurement and units. To avoid inconveniences that would result from this difference, a common scientific system of units of measurements became necessary. In 1968, a group of scientists from different countries met at ‘the conférence Générale des Poids et des Mesures (CGPM)’ (General Conference on Weight and Measures). 

    The system they recommended came to be known as ‘système International d’Unités’ (International System of units) shortened to S.I. units. The system uses seven base units and all others units are derived from these base units by multiplying or dividing one unit by another without introducing a numerical factor.

    NAMES AND SYMBOLS FOR BASE S.I. UNITS.

    Physical quantity

    Name of Si base unit

    Symbol for unit

    Length

    Mass

    Time

    Electric current

    Thermodynamic temperature

    Luminous intensity

    Amount of substance

    Metre

    Kilogramme

    Second

    Ampere

    Kelvin

    Candela

    Mole

    m

    kg

    s

    A

    K

    cd

    mol

    Base quantities and units


    Scientific Measurement tools

     DERIVED UNITS

    Most of the units commonly used are a combination of the basic units. There are given in the table below

    Quantity

    Unit

    Symbol

    Velocity

    Acceleration

    Force

    Energy

    Frequency

    Angle

    Area

    Volume

    Density

    Momentum

    Pressure

    Power

    Electric charge

    Potential difference

    Resistance

    Capacitance

    metre per second

    Metre per second squared

    Newton

    Joule

    Hertz

    Radian

    Square metre

    Cubic metre

    Kilogramme per cubic metre

    Kilogramme metre per second

    Pascal

    Watt

    Coulomb

    Volt

    Ohm

    Farad

    m/s

    m/s2

    N or kg·m/s2

    J or kg·m2/s2

    Hz

    rd

    m2

    m3

    Kg/m3

    Kg·m/s

    Pa

    W or N·m/s

    C

    V

    Ω

    F

    Derived quantities and units


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