If of cast iron weighs 21 g, find the weight of a cast iron pipe of length 1 m with a bore of 3 cm in which the thickness of the metal is 1 cm.
Given,
Weight of 1 cm3 cast iron = 21 g
Length of wire = h = 1 m = 100 cm
Internal radius (r1) =
Thickness of metal = 1 cm
So, External radius (r2) = 1.5 + 1 = 2.5 cm
Volume of metal = (External volume – internal volume)
= πr22h – πr12h = πh (r22 – r12) = × 100 (2.5 + 1.5) (2.5 – 1.5)
= × 100 × 4 × 1 cm3
Weight of metal =