Find the length of 13.2 kg copper wire of diameter 4 mm, when 1 cubic cm of copper weighs 8.4 gm.
Given,
Weight of copper wire = 13.2 kg = (13.2×1000) gm
Diameter of wire = 4mm
So, radius of wire = 
Weight of 1 cm3 wire = 8.4 gm
Let length of wire = h cm
So, volume ×8.4 = 13.2×1000
= πr2h×8.4 = 13.2×1000
= 
= h = 
31