An iron pipe is 42 cm long and its exterior radius is 4 cm. If the thickness of the pipe is 1 cm and iron weights 100 ${\text{g/cm}}^{\text{3}}$ , the weight of the pipe is

Given, length/height of Iron pipe $=42\text{cm}$

Exterior radius $\left(R\right)=4\text{cm}$

Thickness of pipe $=1\text{cm}$

$R-r=1$

$4-r=1$

$r=3\text{cm}$

Weight of iron $=100{\text{g/cm}}^{\text{3}}$

Volume of cylinder $=\pi \left(R+r\right)\left(R-r\right)h$

$=\pi \left(4+3\right)\left(4-3\right)\times 42$

$=\frac{22}{7}\times 7\times 1\times 42$

$=22\times 42$

$=924{\text{cm}}^{\text{3}}$

Weight of pipe $=924\times 100$

$=92400g$

$=92.4\text{kg}$