Part 2. Using a Balance to Measure the Mass of Pennies
Copy the following table into your lab notebook to record your data. Be sure to include units.
In 1983, the composition of pennies was changed from 95% copper to 97.5% zinc coated with a thin layer of copper (2.5%). The size of the pennies remained the same.
Obtain four pre-1982 pennies and four post-1983 pennies. Check the dates on the pennies.
Place a piece of weighing paper on the balance. To tare the weight, zero the balance by briefly pressing the 0/T bar on the balance.
Place one penny on the weighing paper and record the mass and year of the penny in your notebook.
Repeat steps 2-3 for all of the pennies, one penny at a time.
Calculate the average mass (the mean value) for the copper pennies and the average mass of the zinc pennies. Calculate the average deviation from the mean in each case.
6• Look at your data to make sure the results make sense.
