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Chapter 1 Introduction to Scientific Investigation, b) measuring mass, c)…

- - - - do not enter the laboratory w/o permission.
        
        never start an experiment w/o the teacher's instructions.
        
        read & understand the instructions of the experiment beforehand.
        
        use the chemicals & apparatus correctly and carefully.
        
        eating,drinking & playing are prohibited in the laboratory
        
        do not take the apparatus and chemicals out of the laboratory.
        
        1 more item...
    - - do not point the mouth of the test tube at your face/at other ppl
        
        use safety goggles when mixing/heating chemicals
        
        keep highly flammable chemicals away from any heat sources.
        
        do not taste or smell anything unless allowed by the teacher.
- - - - b) measuring mass
        mass of an object : the quantity of matter
        S.I. unit : kilogram (kg)
        
        lever balance
        
        triple beam balance
        
        c) measuring time
        S.I. : second (s)
        
        stopwatch
        
        d) measuring temperature
        
        the degree of heat of an object
        S.I. : Kelvin (K)
        
        laboratory thermometer
        
        clinical thermometer
        
        e) measuring electric current
        
        ammeter
        
        f) measuring volume of water
        
        measuring cylinder
      - ruler
        
        measuring tape
  - - - vernier calipers
        
        used to measure the thickness/outer diamter,inner diameter & depth of an object
        
        smallest division - 0.01 cm / 0.1 mm
        ACTUAL READING=READING OF VERNIER CALIPERS-ZERO ERROR
        
        micrometer screw gauge
        
        used to measure the thickness and diameter of small objects like paper & hair
        
        smallest division : 0.001 cm / 0.01 mm
        more accurate than the vernier calipers
        ACTUAL READING=READING OF MICROMETER SCREW GAUGE-ZERO ERROR
        
        ZERO ERROR
        when the anvil is closed completely.
        
        ZERO ERROR
        when the jaws of the vc are closed.
  - - - The uncertainties in measurement caused by the observer when taking measurements.
        example :
        
        parallax error
        
        carelessness of observer when taking the reading
        
        wrong technique
        
        ways to overcome :
        
        take a few readings of measurement and average reading
        
        reduce the impact of parallax errors,observer"s eyes should be perpendicular to the scale reading
    - - consistent errors obtained from a measuring instrument for every measurement.
        example :
        
        zero occurs
        
        inaccurate measuring instruments
        
        ways to overcome :
        
        conduct experiments with caution
        
        repeat the experiment using different measuring instruments