Question

A cylindrical tube opened at both the ends is made of iron sheet which is $2$ cm thick. If the outer diameter is $16$ cm and its length is $100$ cm, find how many cubic centimeters of iron has been used in making the tube ?

Answer 1

Volume of cylinder $=\pi r^{2}hc{m}^2$
Outer radius $=$ $16/2=8$ cm
Inner radius $=$ $8-2=6$ cm
Volume $=\pi ({r^{\prime }}^2-r^2)h$, where $r$' $=$ outer radius and $r$ $=$ inner radius
$=\pi \times 100\times (8^2-6^2)=8792{cm}^3$
Hence, $8792{cm}^3$ of iron has been used in making the tube.