Question

9. A piece of metal is in the form of a cylinder of radius 0.5 cm and length 7 cm. It is drawn out into
a wire of diameter 1cm. What is the length of the wire so obtained?​

Answer 1

Explanation:

Diameter of metallic cylinder = 1 cm Radius of metallic cylinder = d/2 = 1/2 = 0.5 cm Length of cylinder = 5 cm Diameter of wire drawn from it = 1 mm = 0.1 cm Radius of wire = 0.5mm = 0.05cm Let length of wire be ‘h’ cm Length of wire drawn from metal = volume of metal/ volume of wire = πr2h / πr2 = (½)2 × 5 / (0.05)2 = (5/4) / 0.0025 = 1.25/0.0025 = 500 cm = 5m ∴ Length of the wire is 5m