CLAIM:Pennies are not all copper.
EVIDENCE:The density of copper bar is 8.4 g/cm^3, while the pennies have a density of 6.9 g/mL.
Reason:If the density of the pennies are not the same as the copper bar. The pennies can't be pure copper.
My teacher wants me to find out why pennies are not all copper.
Mint produced more than 130 billion pennies. Then, in 1982 the Mint introduced a penny that is 97.6 percent zinc and only 2.4 percent copper with a density of 7.2 g/mL. By comparison, the old pre-1982 copper pennies were 95 percent copper and 5 percent zinc with a density of 8.8 g/mL.
