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  • An iron pipe 20 cm long has exterior diameter equal to 25 cm . If the thickness of the pipe is 1 cm , find the whole surface of the pipe .

An iron pipe 20 cm long has exterior diameter equal to 25 cm . If the thickness of the pipe is 1 cm , find the whole surface of the pipe .

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solution:   R=External radious =12.5 c

 Rightarrow          r=Internal radious=External radius - thickness) = (12.5 - 1)=11.5 c

  Rightarrow         h=Length of the pipe=20 cm

herefore             Total surface areaof the pipe  =

                 (External curved surface)+(Internal curver surface) + 2(Area of the base of the ring)

                  = 2pi Rh+2pi rh+ 2(pi R^2-pi r^2)

                   =2pi (R+r)h +2pi (R^2-r^2)

                   =2pi (R+r)h +2pi(R+r)(R-r)

                   =2pi(R+r)(h+R-r)

                  =2 imes frac227 imes (12.5+11.5) imes (20+12.5-11.5)cm^2=2 imesfrac227 imes 24 imes21 cm^2

                  =3168 cm^2   

      

 

Posted by

Deependra Verma

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