Question

An iron pipe 20 CM long has exterior diameter equal to 14 CM. If the thickness of the pipe is 1 cm,then find whole surface area of pipe.

Answer 1

Height=20 cm

exterior diameter= 14cm

Therefore, exterior radius(R)=14/2=7.

Thickness of Pipe= 1cm.

Therefore Inner Radius (r)=R - Thickness

7-1=6

Assuming that top and bottom are open, Whole surface area of Pipe=

2πh(R+r) + 2π (R^2-r^2)

2 x 22/7 (7+6) + 2 x 22/7 (7^2-6^2)

=44/7 x 13 + 44/7 x 13

=81.71 x2

=163.428