Question

A hollow cylindrical pipe is 210cm long. Its outer and inner diameters are 10cm and 6cm respectively. The volume of the copper used in making the pipe is

___ ${cm}^3$.

Answer 1

Outer radius = 5 cm

Inner radius = 3 cm

So, volume of copper used = Outer volume - Inner volume

$=\pi$$R^{2}h-\pi$$r^{2}h$

$=\frac{22}{7}\times 5^2\times 210-\frac{22}{7}\times 3^2\times 210$

$=10560{cm}^3$