Question

The external diameter of the barrel of an air-gun is found to be 1.62 cm and the thickness of the metal is 7 mm. Find (in centimetres) the internal diameter .​

Answer 1

Answer :-

• Internal Diameter of Barrel of gun = 0.22 cm

Given :-

• External Diameter = 1.62 cm
• Thickness = 7 mm = 0.7 cm     [1 cm = 10 mm]

To Find :-

• Internal Diameter of Barrel of gun = ?

Explanation :-

In order to find the find the Internal Diameter, First we need to Find the Outer Radius

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

$\rm \odot \: Outer \: Radius \: (R) = \dfrac{1.62}{2} = \bold{0.81 \: cm}$

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Now we need to find the Internal Radius of pipe by Subtracting the Thickness From Outer Radius.

$\blue { \boxed { \bf \bigstar \: Internal \: Radius = Outer \: Radius - Thickness \: \bigstar }}$

$\rm : \: \longrightarrow Internal \: Radius = 0.81 - 0.7 \: cm$

$\pink { \bf : \: \longrightarrow Internal \: Radius = 0.11 \: cm }$

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Now, we will find the Internal Diameter.

$\orange { \boxed { \bf \bigstar \: Diameter = Radius \times 2 \: \bigstar }}$

$\rm : \: \longrightarrow Internal \: Diameter = 0.11 \times 2 \: cm$

$\red { \underline { \boxed { \bf : \: \longrightarrow Internal \: Diameter = 0.22 \: cm }}}$

Hence, the Internal Diameter of the Barrel of the gun is 0.22 cm