Question

How much iron is needed to make a rod of length 90 cm and diameter 1.4cm

Answer 1

$\huge\mathbb{SOLUTION:-}$

$\sf\bullet Height\:of\:rod=90cm\\ \\ \sf\bullet radius=\dfrac{1.4}{2}=0.7cm$

• The rod is in the shape of cylinder so volume of cylinder

$\boxed{\bigstar{\sf{Volume\:of\: cylinder=\pi r{}^{2}h}}}$

$\sf\implies Volume=\dfrac{22}{\cancel7}\times 0.7\times \cancel{0.7}\times 90\\ \\ \sf\implies Volume=22\times 0.7\times 0.1\times 90\\ \\ \sf\implies Volume= 2.2\times 63\\ \\ \sf\implies Volume=138.6cm{}^{3}$

$\underline{\sf{\dag{Volume\:of\:rod\:=138.6cm{}^{3}}}}$

Answer 2

$\huge\bold\green{Question}$

How much iron is needed to make a rod of length 90 cm and diameter 1.4cm ?

$\huge\bold\green{Answer}$

According to the question we have given :-

°•° Height = 90 cm

°•° Radius = 0.7cm

The shape of rod is cylinderical , so by using formula

of volume of cylinder , we can find answer :-

$\tt\green{Volume\:of\: cylinder=\pi r{}^{2}h}$

$\begin{lgathered}\tt = volume=\dfrac{22}{\cancel7}\times 0.7\times \cancel{0.7}\times 90\\ \\ \tt = volume=22\times 0.7\times 0.1\times 90\\ \\ \tt = volume= 2.2\times 63\\ \\ \tt = volume=138.6cm{}^{3}\end{lgathered}$

Hence, the required volume is 138.9 cm³