Question

The external diameter of a $20 \mathrm{~cm}$ long and $1 \mathrm{~cm}$ thick hollow iron pipe is $25 \mathrm{~cm}$. determine the whole surface of the iron pipe. $\left(\right.$ take $\left.\pi=\frac{22}{7}\right)$ [hint. put the value of $\pi$ in the end.]

Answer 1

The whole surface area of the iron pipe is 3318.85 cm².

What is a hollow cylinder?

The hollow cylinder consists of one that is empty on the inside and has a discrepancy in external and internal radius. Examples of hollow cylinders include tubes, round buildings, straws, and so forth.

Now, according to the question;

The length or height of the cylinder is; h = 20 cm.

The outer diameter is given as 25 cm

Thus, the outer radius will be; R = 25/2 cm.

The thickness of the pipe is 1 cm.

So, the inner radius will be; r = (25-2)/2 = 23/2 ( 2 for both side)

The curved surface area of the outer surface = 2$\pi$Rh

= 2$\pi$(25/2)×20

= 500$\pi$

Similarly, the curved surface area of the inner surface = 2$\pi$rh

= 2$\pi$(23/2)×20

= 460$\pi$

The area of the top and bottom surface of the pipe = 2$\pi$(R + r)(R - r)

= 2$\pi$(25/2 + 23/2)(25/2 - 23/2)

On simplification,

= 96$\pi$

The whole area of the pipe = external area + internal area + bottom and top area

Area = 500$\pi$  + 460$\pi$ + 96$\pi$

        = 1056$\pi$

Substitute the value of   $\left.\pi=\frac{22}{7}$  

Area = 3318.85

Therefore,  the whole surface area of the iron pipe is 3318.85 cm².

To know more about the hollow cylinder, here

https://brainly.com/question/15247285

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The correct question is-

The external diameter of a $20 \mathrm{~cm}$ long and $1 \mathrm{~cm}$ thick hollow iron pipe is $25 \mathrm{~cm}$. determine the whole surface area of the iron pipe. Take  $\left.\pi=\frac{22}{7}$  [hint. put the value of $\pi$ in the end.]