Question

A cylindrical roller made of iron is $2\text{m}$ long. Its inner diameter is $35\text{cm}$ and the thickness is $7\text{cm}$ all round. Find the weight of the roller in $\text{kg}$, if weight of $1{\text{cm}}^3$ of iron is $8\text{g}$.

Answer 1

Volume of cylindrical roller $=\pi h(R^2-r^2)$

Where $R$ is outer radius and $r$ is inner radius.

Given:

$R=21\text{cm}$

$r=17.5\text{cm}$

$h=200\text{cm}$

$V=200\pi ({21}^2-{17.5}^2)$

$V=84623{\text{cm}}^3$

Given $1{\text{cm}}^3$ of iron weights $8\text{g}$.

Then, total weight of roller $=84623\times 8=676984\text{gm}=676.984\text{kg}$