Determining Density

Mass Density

• Mass density is a measure of mass per volume

• Formula sheetHigh Density Low Density

M = VDm

Rearrange to solveNow needM and V

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 ft3)– SI: Cubic centimeter or meter (cm3 or m3)

Material Mass Density (kgm-3)Atmosphere (Earth @ Sea Level) 1.2

Water (Pure) 1,000

Water (Sea) 1,030

Aluminum 2,700

Steel (1018) 7,833

Lead 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

VolumeChange

Meniscus shape isexagerated for clarity

Read level here

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?