Determining Densities
Students use two different methods to determine the densities of a variety of materials and objects. The first method involves direct measurement of the volumes of objects that have simple geometric shapes. The second is the water displacement method, used to determine the volumes of irregularly shaped objects. After the densities are determined, students create x-y scatter graphs of mass versus volume, which reveal that objects with densities less than water (floaters) lie above the graph's diagonal (representing the density of water), and those with densities greater than water (sinkers) lie below the diagonal.
The concept of density has many useful applications. This image is an electron density map, which is used by biochemists to help understand the structure of proteins.Copyright Argonne National Laboratory http://www.anl.gov/OPA/logos18-2/photos/edm.jpg
Density is an important property in many materials engineering applications. Students make measurements and calculations to determine the densities of a wide range of objects, then compare them to known densities determined from precise laboratory measurements and calculations.
After this activity, student should be able to:
- Describe a method for determining the density of an object or material that has a simple geometric shape (rectangular prism, sphere or cylinder).
- Describe a method for determining the density of an object or material that has a complex geometric shape.