Question

A solid iron pole consists of a cylinder of height $220$ cm and base diameter $24$ cm, which is surmounted by another cylinder of height $60$ cm and radius $8$ cm. Find the mass of the pole, given that 1 $c{m}^3$ of iron has approximately $8$ g mass. (Use $\pi$ = 3.14)

Answer 1

Height ($h_1$) of larger cylinder $=220$ cm
Radius ($r_1$) of larger cylinder = $\frac{24}{2}=12$ cm
Height ($h_2$) of smaller cylinder = $60$ cm
Radius ($r_2$) of smaller cylinder =$8$ cm
Total volume of pole = Volume of larger cylinder + Volume of smaller cylinder

$=\pi r_1^2{h}_1+\pi r_2^2{h}_2$

$=\left(\pi \right(12{)}^2\times 220)+(\pi (8{)}^2\times 60)$

$=\pi [144\times 220+64\times 60]$

$=3.14[31,680+3,840]$

$=3.14\times 35520=111,532.8$ cm ${}^3$

Mass of 1 $c{m}^3$ iron = $8$ g

Mass of $111532.8$ cm ${}^3$ iron = $11532.8\times 8=892262.4$ g