Question

The external diameter of a 20 cm long and 1cm thick hollow iron pipe is 25cm. Determine the whole surface of the iron pipe.(take π=22/7)​

Answer 1

Answer :-

• The whole surface of the iron pipe​ = 3168 cm²

Given :-

• External Diameter = 25 cm
• Thickness = 1 cm
• Length (Here Height) = 20 cm

To Find :-

• The whole surface of the iron pipe​ = ?

Explanation :-

In order to find the Whole Surface Area of the Hollow Pipe, First We need to find the Internal Radius and External Radius.

$\blue { \boxed { \bf \bigstar \: Radius = \dfrac{Diameter}{2} \: \bigstar }}$

$\rm \odot \: External \: Radius \: (R) = \dfrac{25}{2} = \bold{12.5 \: cm}$

$\rm \odot \: Internal \: Radius \: (r) = 12.5 - 1 = \bold{11.5 \: cm}$

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Now, we will find the TSA of Hollow Pipe

$\blue { \boxed { \bf \bigstar \: TSA \: of \: Hollow \: Pipe = 2 \pi h(R+r) + 2 \pi (R^2 - r^2) \: \bigstar }}$

$\rm : \: \implies 2 \times \frac{22}{7} \times 20 (12.5 + 11.5) + 2 \times \frac{22}{7} \times [(12.5)^2 + (11.5)^2]$

$\rm : \: \implies (\frac{880}{7} \times 24) + (\frac{44}{7} \times 156.25 + 132.25)$

$\rm : \: \implies \frac{21120}{7} + \frac{1056}{7}$

$\rm : \: \implies \frac{22176}{7}$

$\red { \underline { \boxed { \bf : \: \implies 3168 \: cm^2 }}}$

Hence, the WSA(TSA) of the Hollow pipe is 3168 cm².