An object has mass 50g and displaces 25mL of water. What is its density?

Ρ = m/V = 50g / 25mL = 2 g/cm³.

Will the object above float in water (ρ=1 g/cm³)?

2 g/cm³ > 1 g/cm³ → it sinks.

A hollow metal sphere appears to have lower density than expected. Why?

The hollow space increases volume without adding mass.

Pro 🔒~15 min

Density Lab

Measure mass and volume to determine density

How it works

Density is the ratio of mass to volume (ρ = m/V). Different materials have characteristic densities — iron is ~7874 kg/m³, water is 1000 kg/m³, and wood is typically 400–900 kg/m³. Water displacement is the standard method for measuring irregular volumes: immerse an object in water and measure the volume increase. Density determines whether an object floats or sinks.

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Step-by-step

Select a material and place the object on the scale to measure mass.
Submerge it in the graduated cylinder to measure displaced volume.
Calculate density and compare with reference values.
Try predicting float/sink behavior before testing in the tank.

Key formulas

$\rho = \frac{m}{V}$ Density
$V = V_{final} - V_{initial}$ Volume by water displacement

Frequently asked questions

An object has mass 50g and displaces 25mL of water. What is its density?: Ρ = m/V = 50g / 25mL = 2 g/cm³.
Will the object above float in water (ρ=1 g/cm³)?: 2 g/cm³ > 1 g/cm³ → it sinks.
A hollow metal sphere appears to have lower density than expected. Why?: The hollow space increases volume without adding mass.