Question

Question 3
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 $\frac{g}{c{m}^3}$?
$[Assume\pi =\frac{22}{7}]$

Answer 1

Radius (r) of the metallic ball
$=\left(\frac{4.2}{2}\right)cm=2.1cm$

Volume of the metallic ball
$=\frac{4}{3}\pi r^3$
$=[\frac{4}{3}\times \frac{22}{7}\times (2.1{)}^3]c{m}^3$
$=38.808c{m}^3$

$Density=\frac{Mass}{Volume}$
$Mass=Density\times Volume$
$=(8.9\times 38.808)g$
$=345.3912g$

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