# AQA A-Level Physics/Density

Density at A-Level is no different to density at GCSE. You should recall that density is defined as measure of a material's mass per unit volume. Using this definition we can work out that density, $\rho =\frac { m }{ V }$, where $m$ is mass, in kg, and $V$ is volume in cm-3. Once again, using the formula, it can be found that density has the units kgˑm3, since it is a fraction of kg over cm3.

A more dense material will be heavier than a less dense material of the same volume, since a smaller numerator in the fraction reduces the value of $\rho$

## Experiment to measure density

You are required to be able to state a method in order to measure the density of a given object.

1. The first step is to measure the objects mass. This should be done using a set of scientific balances of sufficient precision (e.g. ±0.001 grams). Record this value.
2. If the object is irregular, fill a beaker or measuring cylinder enough to cover the object once it is submerged and measure this initial volume. Place the object into the container and measure the new volume. The volume of the object itself is $\Delta V$, found by subtracting the initial volume from the final volume.