Science
What is Density?
Density is how much mass is packed into a given space — mass divided by volume. It's why a small steel ball sinks but a huge ship floats, and why oil floats on water: less dense things rise, denser things sink.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains density.
Key things to understand
- 1How much mass fits in a given volume.
- 2Density = mass ÷ volume.
- 3Denser-than-water things sink; lighter ones float.
- 4Explains floating, sinking, and why oil sits on water.
Frequently asked questions
- How do you calculate density?
- Divide an object's mass by its volume (density = mass ÷ volume); common units are g/cm³ or kg/m³.
- Why do some things float?
- An object floats when it's less dense than the liquid around it, so the liquid can hold its weight up.
- Does temperature change density?
- Yes — most things expand when heated, spreading the same mass over more volume, so they become less dense.