Determining Density

Mass Density • Mass density is a measure of mass per volume • Formula sheet High Density M = VD m Rearrange to solve Now need M and V Low Density

Mass Density: Mass per Volume • Mass measured in units such as – US Customary: ounces (oz) or pounds (lb) – SI: grams (g), kilograms (kg) • Volume measured in units such as – US Customary: Cubic inches or feet (in.

3 or ft 3 ) – SI: Cubic centimeter or meter (cm 3 or m 3 )

Material

Atmosphere (Earth @ Sea Level) Water (Pure) Water (Sea) Aluminum Steel (1018) Lead

Mass Density (kgm -3 )

1.2

1,000 1,030 2,700 7,833 11,340

Sources of Mass and Volume Measurement • Mass – Typically measured directly using a scale • Volume – Calculate based on geometry and dimension measurements – Indirect measurement using water displacement or 3D scanner

Volume: Calculation • Some object volumes can be calculated • What is the volume formula for each object?

Volume: Indirect Measure • Volume of an irregular object can be determined indirectly with fluid displacement Level Elevates

Volume: Indirect Measure • Record water level with only water • Add samples • Record new level • Difference is sample volume Read level here Volume Change Meniscus shape is exagerated for clarity

Example • What is the density of a 1.12 in. sphere of titanium that weighs 0.96 lb • What volume of water would it displace?