Question

Find the volume of a sphere whose radius is :
i.7cm
ii.0.63cm

Answer 1

Hint: Use the formula for volume of sphere and then substitute the value of r to obtain the required value of volume.
Volume of a sphere = $4/3\pi r^3$

Complete step-by-step answer:

For r = 7 cm
We know,
Volume of a sphere = $4/3\pi r^3$
Substituting the value of r, we get:
 $$4/3\pi r^3=4/3\pi (7{)}^3$$
$$\begin{gathered} =(4/3)(22/7)\times 7\times 7\times 7 \\ =4312/21 \end{gathered}$$
 Volume $$=1437.33$$cm³

ii) For r = 0.63 m

   We know,
   Volume of a sphere = $4/3\pi r^3$
   Substituting the value of r, we get:
   $$4/3\pi r^3=4/3\pi (0.63{)}^3$$
$$\begin{gathered} =(4/3)(22/7)\times 0.63\times 0.63\times 0.63 \\ =(4/3)(22/7)(63/100)(63/100)(63/100) \end{gathered}$$
(To remove decimal and make calculation easier)
$$=22004136/21000000$$
 Volume $$=1.0478$$m³
Therefore Volume of the sphere when radius= 7cm is 1437.33 cm3 and when radius is 0.63 cm, it is 1.0478 m³.

Note: Be very careful with the units, for the radius given in cm, the volume will be in cm3 and for m, the volume will be in m3.
A sphere is a three dimensional (3 – D) figure and in simple terms the boundary occupied by a 3 – D object is referred to as volume.
In the sphere, the width, circumference and mean curvature are constant.