The diameter of a metallic ball is 4.2 cm. What is the mass of the ball, if the density of the metal is 8.9 g per \({cm}^3\) ?

Given :
Radius of sphere = \(\frac{4.2}{2} cm = 2.1 cm\)

We know that,
Volume of sphere
= \(\frac{4}{3}{\pi}{r}^3\)
= \(\frac{4}{3} × \frac{22}{7} × {2.1}^3\) \({cm}^3\)
= \(38.808\) \({cm}^3\)

Now, we know that,

\(Density = \frac{Mass}{Volume}\)
\(\Rightarrow \) Mass = Density × Volume
\(\Rightarrow \) = 8.9 × 38.808 g
\(\Rightarrow \) = 345.3912 g

Hence, the mass of the ball is 345.39 g (approximately).