Density

We have been digging into density lately. We have reviewed the formumla: Density = Mass divided by volume (How many grams per cubic centimeter, or milliliter?). The homework introduced the concept and we did some practice math problems in class. Today we measured the density of pennies from before 1982 and after 1982. In 1982 they switched from making pennies out of mostly copper (95% copper and 5% zinc) to making them mostly out of zinc with a copper coating (2.5% copper and 97.5% zinc). Zinc is less dense than copper and we were able to show that by measuring the mass and volume of pennies from before and after 1982. No homework this week, Adolescent Issues and MLK Day have taken up most of our week.