Density: Mass and Volume

What is Density?

Density is a measure of how “packed” matter is in an object. It is defined as mass per unit volume.

• SI Unit: $kg/m^3$
• Common Unit: $g/cm^3$ or $g/mL$

Measuring Density

To find the density of an irregular stone:

1. Find Mass ($m$): Weigh it on a digital balance.
2. Find Volume ($V$): Use the water displacement method in a measuring cylinder.
   • $V = \text{Final Water Level} - \text{Initial Water Level}$.
3. Calculate: Divide Mass by Volume.

Factors Affecting Density

1. Temperature: generally, heating causes expansion (Volume increases), so Density decreases.
   • Hot air rises because it is less dense than cold air.
2. Pressure: High pressure compresses gases (Volume decreases), so Density increases.