Question: User: why is the unit m³?
1. **State the problem:** We want to understand why the volume unit is $m^3$ (cubic meters).
2. **Explain volume units:** Volume measures the amount of space an object occupies.
3. **Unit derivation:** Since length is measured in meters ($m$), volume is measured in cubic meters ($m^3$) because volume is length \times width \times height.
4. **Formula:** $$\text{Volume} = \text{length} \times \text{width} \times \text{height}$$
5. **Units multiplication:** Each dimension is in meters, so multiplying three lengths gives:
$$m \times m \times m = m^3$$
6. **Conclusion:** Therefore, volume is expressed in cubic meters ($m^3$) because it represents three-dimensional space.