Two students are given a small cylinder of aluminium of known mass and asked to determine its density. (The density of aluminium is 2.702 g/cm3.) Since density is mass/volume, ‘accepted’ the students need to calculate the volume of the cylinder. To do this, the height and diameter of the cylinder need to be measured. Student A is told to use a simple plastic ruler and to make four independent measurements for each dimension. Student B is told to use a precision measuring tool called a micrometer. Student A plastic ruler Student B micrometer – – 2.2 g/cm3 2.703 g/cm3 2.3 g/cm3 2.701 g/cm3 2.7 g/cm3 2.705 g/cm3 2.4 g/cm3 5.811 g/cm3 Calculate the average value for each set of density values, making sure that any are ‘outliers’ not included. Student A plastic ruler Student B micrometer – – Calculate the % error for each set of values. Student A plastic ruler Student B micrometer – – Compare the average value for each set with the accepted value:
Two students are given a small cylinder of aluminium of known mass and asked to determine its density. (The ‘accepted’ density of aluminium is 2.702 g/cm3.) Since density is mass/volume, the students need to calculate the volume of the cylinder. To do this, the height and diameter of the cylinder need to be measured. Student A is told to use a simple plastic ruler and to make four independent measurements for each dimension. Student B is told to use a precision measuring tool called a micrometer. Student A – plastic ruler Student B – micrometer 2.2 g/cm3 2.3 g/cm3 2.7 g/cm3 2.4 g/cm3 2.703 g/cm3 2.701 g/cm3 2.705 g/cm3 5.811 g/cm3 Calculate the average value for each set of density values, making sure that any ‘outliers’ are not included. Student A – plastic ruler Student B – micrometer Calculate the % error for each set of values. Student A – plastic ruler Student B – micrometer Compare the average value for each set with the accepted value:
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