Iron pole

What is the mass of a pole with the shape of a regular quadrilateral prism with a length of 1 m and a cross-sectional side length of a = 4.5 cm made from iron with density ρ = 7800 kg/m³?

Correct answer:

m =  15.795 kg

Step-by-step explanation:

$$\begin{gathered} \rho =7800{\text{kg/m}}^3 \\ c=1\text{m} \\ a=4.5\text{cm}\to \text{m}=4.5:100\text{m}=0.045\text{m} \\ V=a^2\cdot c=0.045^2\cdot 1=\frac{81}{40000}\doteq 0.002{\text{m}}^3 \\ m=\rho \cdot V=7800\cdot 0.002=15.795\text{kg} \end{gathered}$$

Try another example