A iron pipe is 21 m long and its exterior diameter is 8cm.If the thickness of the pipe is 1cm and iron weight 8g/cm3,find the weight of pipe?
Given: External diameter = 8 cm
Then
External radius = 4 cm,
Internal radius = 4-1=3 cm.
∴Volume of iron = {(22/7)* [(4)2 - (3)2] x 21} cm3= {(22/7)*7*1*21} cm3 = 462 cm3
⇒Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.