Question

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${}^3$?

Answer 1

Given that,

The diameter of a metallic ball is $4.2cm$.

The density of the metal is $8.9g/c{m}^3$

To find out,

The mass of the ball.

We know that, $\text{Mass}=\text{Volume}\times \text{Density}$

Also, a ball is spherical in shape.

And, volume of a sphere $=\frac{4}{3}\pi r^3$

Here, $r=\frac{4.2}{2}=2.1cm$

Hence, volume of the ball $=\frac{4}{3}\times \frac{22}{7}\times (2.1{)}^3[\because \pi =\frac{22}{7}]$

$=\frac{814.97}{21}$

$=38.81c{m}^3$

So, mass of the ball $=38.81\times 8.9$

$=345.41g$

Hence, the mass of the ball is $345.41g$.