Question

An iron pipe is 21 m long and its exterior diameter is 8 cm if thickness of pipe is one cm & height and weight is 8 g/cm^3 find the weight of pipe

Answer 1

In this type of question, we need to subtract external radius and internal radius to get the answer using the volume formula as the pipe is hollow. Oh! line become a bit complicated, sorry for that, lets solve it.

External radius = 4 cm
Internal radius = 3 cm [because thickness of pipe is 1 cm]

Volume of iron =πr2h=227∗[42−32]∗21cm3=227∗1∗21cm3=462cm3Volume of iron =πr2h=227∗[42−32]∗21cm3=227∗1∗21cm3=462cm3


Weight of iron = 462*8 = 3696 gm 
= 3.696 kg