Question

A metal pipe is 154 cm long. The inner diameter of a cross-section is 8 cm, the outer diameter being 8.8 cm.

Find its total surface area. ​

Answer 1

Answer:

Length =77cm, 

Inner diameter =4cm, hence inner radius (r)=2cm

outer daimeter =4.4cm, hence outer radius (R) =2.2cm

Height of the pipe =length

⇒Inner surface area ( inner CSA) = 2πrh

⇒ Inner CSA = 2×722×2×77

⇒Inner CSA = 968cm2

Outer CSA= 2πRh

⇒Outer CSA = 2×722×2.2×77

⇒Outer CSA= 1064.8cm2 

Now the total surface area on the ends = 2π(R−r)(R+r)

⇒2×722×4.2×0.2

⇒5.28 cm

The total surface area=outer CSA + Inner CSA + TSA on the ends 

The total surface area = 1068.8+968+5.28

The toal surface area = 2038.08 cm2