Question

the inner and outer radii of a cylindrical pope are 4 cm and 5 cm respectively find the area of cross section of the pipe

Answer 1

Area = π(5^2-4^2) = 9π cm^2

Answer 2

Explanation:

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=462cm3