Find the mass of a 3.5 m long lead pipe,

Length of the pipe (h) = 3.5 cm = 300 cm

External radius of the pipe $(R)=\frac{2.4}{2}=1.2 \mathrm{~cm}$

Thickness of pipe $=2 \mathrm{~mm}$

$=0.2 \mathrm{~cm}$

So internal radius of pipe $=1.2-0.2$

$=1 \mathrm{~cm}$

Thus volume of pipe $=\pi\left(R^{2}-r^{2}\right) h$

$=\frac{22}{7} \times\left((1.2)^{2}-1^{2}\right) \times 300$

$=22 \times 50 \times 0.44 \mathrm{~cm}^{3}$

$=484 \mathrm{~cm}^{3}$

Mass of 1 cm3 pipe is 11.4 gm

Total mass = 4184 × 11.4 = 5517.6 gm = 5.518 kg.