Calculate the density (in kg/m³) of a metallic ball having mass 1.75 g and diameter of 7.6 mm.

Radius of ball,

r = Diameter /2 = 7.6 mm/2 =3.8mm

$\therefore$ Volume $=\frac{4}{3}\times \pi \times r^3$

$\begin{array}{l}\mathrm{Volume}=\frac{4}{3}\times \frac{22}{7}\times (3.8 \mathrm{mm}{)}^3\\ =230 {\mathrm{mm}}^3\end{array}$

Density is calculated as:

$\text{ Density }=\frac{\text{ Mass }}{\text{ Volume }}=\frac{1.75 \mathrm{g}}{230 {\mathrm{mm}}^3}$

$\begin{array}{l}\mathrm{Density}=\frac{1.75\times {10}^{-3} \mathrm{kg}}{230\times {10}^{-9} {\mathrm{m}}^3}\\ \left[\because 1 \mathrm{kg}={10}^3 \mathrm{g}; 1 \mathrm{mm}={10}^{-3} \mathrm{m}\right]\end{array}$

Density $=7608.69 \mathrm{kg} {\mathrm{m}}^{-3}$