Question

Find the mass of a 3.5 m long lead pipe, if the external diameter of the pipe is 2.4 cm, thickness of the metal is 2 mm and mass of $1c{m}^3$ of lead is 11.4 g. (Take $\pi$ = 22/7)

• A. 5.518 kg
• B. 6.518 kg
• C. 7.518 kg
• D. 8.518 kg

Answer 1

Answer: (A)

5.518 kg

Length of pipe $=3.5m=350cm$

external diameter of the pipe $=2.4cm$,
external radius of the the pipe $=1.2cm$
thickness of the metal $=2mm=0.2cm$

so, internal radius $=$ external radius- thickness $=1.2cm-0.2cm=1cm$

Volume of pipe $=V=\Pi (R^2-r^2)h$
$V=\Pi ({1.2}^2-1^2)\ast 350$
$V=484c{m}^3$

As per question,
mass of $1c{m}^3$ of lead $=11.4g.$
mass of $484c{m}^3$ of lead $=11.4\ast 484g=5517.6g=5.518kg$