Radius of Spheres

The formula for the volume of a sphere, V, in terms of its radius, r, is:

  V = 4/3πr³

We can rearrange this formula to make r the subject.

The formula for the radius of a sphere, r, in terms of its volume, V, is:

Example

Calculate the radius, r cm, of a sphere which has a volume of 100 cm³. 

Give your answer to 3 sig. figs.

Answer

r³ = 3 x 100 ÷ (4 x π) = 23.873

r = ^₃√23.873 = 2.8794 ≈ 2.88 cm (3 s.f.)