Let h and r be the original height and radius of iron rod Since, iron-rod is in cylindrical form ∴ initial volume =πr2h After recasting Volume =πr2h where h' is the new height =π(
r
4
)2h′ Since, its volume remains constant ∴πr2h=πr2h′ πr2h=π(
r
4
)2h′ h=
hI
16
⇒h′=16h Hence, the new length will become 16 times of the original