A metal pipe is 77cm long. The inner diameter of a cross section is 4 cm, the outer diameter being 4.4 cm. Find its
(i)inner curved surface area
(ii)outer curved surface area
(iii)total surface area
Length of pipe = 77 c.m.
Inner diameter = 4 c.m.
Outer diameter = 4.4c.m.
1) Inner curved surface area
radius = inner diameter / 2 => 4 c.m./2 => 2 c.m.
curved surface area = 2 / rh => 2* 22 * 77 => 2 *22* 11 = 968 c.m.2
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2). Outer curved surface area
radius = outer diameter / 2 => 4.4 c.m. / 2 => 2.2 c.m.
curved surface area = 2 / rh
= 2 * 22* 2.2* 77
__________________ => 1064.8 c.m.2
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3) total surface area
Let outer radius be R and inner radius be r
surface area on the end = 2 / ( R+r )( R -r )
= 2 *22 * ( 2.2 + 2) ( 2.2 -2)
__
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= 2* 22* 4.2 * 0.2
________________ = 5.28 c.m.2
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total surface area = 968 c.m.2 + 1064.8 c.m.2 +5.28 c.m.2 = 2038.08 c.m. 2