Question

a hollow cylinderical pipe is made of copper .the volume of the metal used in the pipe is 2640 cubic cm .its external radius is 7cm and length is 21 cm .find the thickness of the pipe​

Answer 1

$\underline{A \:hollow\: cylinder \:pipe\: is \:made \:up \:of}$ $\underline{copper.\: The\: volume\: of\: metal \:used\: in}$ $\underline{pipe \:is \:2640 \:cubic\: cm.\: It's \:external}$ $\underline{radius\: is\: 7 \:cm\: and \:length\: is \:21\: cm.\: Find}$ $\underline{the\: thickness\: of \:the\: pipe.}$

$\huge\underline{\bold{\red{Answer}}}$

Given;

$\textbf{Length of pipe (height) = 21 cm}$

$\textbf{External Radius = 7 cm}$

$\textbf{Vol of metal used = 2640 cubic cm}$

$\textbf{Let R be the external radius and r be}$ $\textbf{internal radius.}$

$\boxed{Vol\: of \:cylindrical \:pipe \:= \:Vol \:of\: metal\:used}$

π (R² - r²) h = 2640

$\frac{1}{2}$ × [(7)² - (r)²] × 21 = 2640

$\frac{1}{2}$ (49 - r²) 21 = 2640

22 × (49 - r²) × 3 = 2640

49 - r² = $\dfrac{2640}{66}$

49 - r² = 40

- r² = 40 - 49

- r² = - 9

r² = 9

r = √9

r = ± 3

$r\:=\:-\:3\:cm$ (Not possible)

So,

$r\:\:=\:+\:3\:cm$

$\textbf{Thickness = R - r}$

= 7 - 3

= 4 cm

$\boxed{\boxed{Thickness \:of\: the\: pipe\: is\: 4\: cm}}$

Answer 2

Step-by-step explanation:

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hope it's help u