How to Calculate the Density of Solids & Liquids

Calculating the density of various objects is a perfect classroom science experiment.

The density of an object is a measure of mass per unit of volume. You can find it by dividing the object's mass by its volume: Density = Mass/Volume. You can easily measure the mass of a solid or liquid using a scale, and find the volume of a liquid by using a graduated cylinder. Because of Archimedes' Principle, which the great Greek mathematician and physicist discovered in the 3rd century BCE, you can also use a graduated cylinder to easily calculate the volume of a solid. Archimedes found that any solid completely submerged in a liquid will displace its volume of that liquid.

Things You'll Need

• Graduated cylinder
• Scale
• Calculator

Instructions

Calculate the Density of a Liquid

1. Measure and record the mass of the empty graduated cylinder on the scale.

2. Fill the graduated cylinder with the liquid of unknown density until the liquid reaches one of the measuring lines. That number is the volume of the liquid.

3. Measure the filled cylinder on the scale.

4. Subtract the mass of the empty cylinder from the mass of the filled cylinder. This is the mass of the liquid.

5. Divide the mass of the liquid by its volume. The result is the density of the liquid.

Calculate the Density of a Solid

1. Measure and record the mass of the solid on the scale.

2. Fill the graduated cylinder with water until the water reaches one of the measuring lines. Record this number.

3. Submerge the solid in the water; the water must cover it entirely.

4. Record the new water level.

5. Subtract the new water level from the initial water level. This is the volume of water the solid has displaced, and, according to Archimedes' Principle, it is also the volume of the solid.

6. Divide the mass of the solid by its volume. The result is the density.

References

• Cenco Physics; Densities of Solids and Liquids; B. Pearson; July 2009