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Physics 2.1 Take measurements of physical quantities and analyse data graphically to determine a relationship

Achievement criteria

The criteria for each level of achievement is based on the ability to use instruments to take measurements of physical quantities using techniques that increase accuracy, and the ability to analyse data to determine increasing complex relationships.

Assessment will include:

• the use of instruments that:
  • have potential for a parallax error
  • require a zero error correction or reading
  • have more than one scale to select from
    
    (You must demonstrate the measurement of at least three different physical quantities and use at least three different types of measuring instruments.)
• familiarity with the following graphs:
  • linear
  • square
  • inverse
  • inverse square.

Analysis will not include exponential or log graphs.

Achievement

• Use instruments to take measurements of physical quantities. Instruments are set up and connected or operated in order for you to take a measurement. You must record a unit along with the measurement.
• Use graphical techniques in analysing data to determine the type of relationship between two variables. Graphical techniques could include:
  • data plotted correctly
  • choice of appropriate axes and scales
  • axes labelled with quantities and units
  • a line of best fit.
  
  Use the shape of the graph to suggest the type of relationship.
  
  

Achievement with Merit

• Use instruments to take measurements of physical quantities using techniques that increase accuracy, such as:
  • placement of the observer and/or the instrument
  • appropriate significant figures
  • zero error correction
  • averaging repeated measurements
  • number of readings sufficient for purpose.
  
  Techniques could be observed, stated or obvious from the data measurements.
  
  
• Use graphical techniques in analysing data to determine the equation of a linear relationship and the value of a physical quantity. You will be required to:
  • plot the data
  • calculate a gradient and intercept, where relevant
  • state the mathematical relationship between the two variables
  • determine a physical quantity from the gradient or intercept.

Achievement with Excellence

• Use instruments to take measurements of physical quantities using techniques that increase accuracy. Justify the techniques used to increase the accuracy of the measurements, by providing an explanation of the rationale for using the techniques.
  
  Note: The result of a measurement will, in general, differ from the true value of the quantity being measured, due to the limitations of the measuring equipment and the measurement procedure. Such a difference is called a measurement error. There are two types of measurement error: systematic error and random error.
  
  An accurate measurement is one for which both systematic errors and random errors are relatively small.
  
  A precise measurement is one for which the random errors are relatively small.
  
  
• Use graphical techniques in analysing data to determine the equation of a non-linear relationship and the value of a physical quantity. You will be required to:
  • process the data from a non-linear graph to enable a linear graph to be constructed
  • determine a gradient and intercept, where relevant
  • state a mathematical relationship between the two variables
  • determine a physical quantity, with its unit, from the gradient or intercept.

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