To find the density of a cube, you can use the formula:
\[ \text{Density} = \frac{\text{Mass}}{\text{Volume}} \]
First, calculate the volume of the cube. The volume \( V \) of a cube with side length \( s \) is given by:
\[ V = s^3 \]
In this case, the side length \( s \) is 2 meters:
\[ V = 2 , \text{m} \times 2 , \text{m} \times 2 , \text{m} = 8 , \text{m}^3 \]
Now, you can use the mass and the volume to find the density. Given the mass \( m \) is 40 kg:
\[ \text{Density} = \frac{40 , \text{kg}}{8 , \text{m}^3} = 5 , \text{kg/m}^3 \]
Therefore, the correct response is:
5 kg/m³