The prison ball

Calculate the density of the material from which the prison ball is made if you know its diameter is 15cm and its weight is approximately 2.3kg. With the help of mathematical-physicochemical tables, estimate what material the ball is made from.

Correct answer:

h =  1301.5338 kg/m³

Step-by-step explanation:

$$\begin{gathered} D=15\text{cm}\to \text{m}=15:100\text{m}=0.15\text{m} \\ m=2.3\text{kg} \\ r=D/2=\frac{3}{20}/2=\frac{3}{20\cdot 2}=\frac{3}{40}=0.075\text{m} \\ V=\frac{4}{3}\cdot \pi \cdot r^3=\frac{4}{3}\cdot 3.1416\cdot 0.075^3\doteq 0.0018{\text{m}}^3 \\ h=m/V=2.3/0.0018=1301.5338{\text{kg/m}}^3 \end{gathered}$$

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