Question

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

Answer 1

Given: In hollow cylindrical pipe,

length of the pipe $\left(h\right)=210cm$.

Outer diameter $\left(D\right)=10cm$

$\Rightarrow$ Outer radius $\left(R\right)=\frac{10cm}{2}=5cm$

Inner diameter $\left(d\right)=6cm$

Inner radius $\left(r\right)=\frac{6cm}{2}=3cm$

So, volume of cylinder used $=$ (Outer volume - Inner volume)

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

$=\pi h(R^2-r^2)$

$=\frac{22}{7}\times 210\left(\right(5{)}^2-\left(3{)}^2\right)$
$=\frac{22}{7}\times 210\times (25-9)$

$=\frac{22}{7}\times 210\times 16$

$=22\times 30\times 16$

$=10560c{m}^3$

Therefore, the volume of the copper used in making the pipe is $10560c{m}^3$.