Question

A metal pipe is 77 cm long. The inner diameter of a cross section is 4 cm, the outer diameter being 4.4 cm.

(i) Inner curved surface area,

(ii) Outer curved surface area,

(iii) Total surface area.

[ Assume π = 22/7 ]

Answer 1

Inner radius (r₁)of cylindrical pipe = (4/2)cm = 2cm

Outer radius (r₂) of cylindrical pipe = (4.4/2)cm = 2.2cm

Height (h) of cylindrical pipe = Length of cylindrical pipe = 77 cm 

(i) CSA of inner surface of pipe = 2πr₁h

= ( 2 x 22/7 x 2 x 77 )cm = 968cm²

(ii) CSA of outer surface of pipe 2πr₂h

= ( 2 x 22/7 x 2.2 x77 )cm²

= ( 22 x 22 x 22 )cm²

= 1064.8cm²

(iii) Total surface area of pipe = CSA of inner surface + CSA of outer surface + Area of both circular ends of pipe

Therefore, the total surface area of the cylindrical pipe is 2038.08 cm².