A Level Physics Practice Exam

How is the density of a material defined?

1. Volume divided by mass

2. Mass divided by surface area

3. Mass divided by volume

4. Weight divided by volume

The correct answer is: Mass divided by volume

The correct definition of density is mass divided by volume. Density is a measure of how much mass is contained in a given volume of a material. It provides insight into how tightly compacted the material's particles are. When calculating density, you take the total mass of the material and divide it by the volume it occupies. This gives you a value that is often expressed in units such as kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³). It's important to note that while other combinations like weight divided by volume are related to specific contexts (such as buoyancy), the standard definition of density is universally recognized as the mass-to-volume ratio. Surface area is not relevant in the standard definition of density, which is why the other options do not correctly describe how density is defined.