Question

The curved surface area of a cylinder is 1000 cm^2. A wire of diameter 5 mm is wound round it so as to cover it completely. Find the length of the wire.

Answer 1

Length of wire = CSA of cylinder/diameter
= 1000×10/5
= 2000 cm
Answer.

Answer 2

HELLO DEAR,

Let the no. of turns the wire makes on the cylinder be n

∴ the height of the cylinder = diameter of the wire x n = 5 x n mm = 0.005 m

Let the length of wire needed be L m
But the wire makes n turns over the cylinder,
so L = 2πr x n

⇒ L/n = 2πr.

Curved surface area of the cylinder =
2πrh

2πrh = 1000 cm² = 0.1 m²

0.005n x L/n = 0.1


⇒ L = 0.1/0.005 = 100/5 = 20 m = 20*100cm = 2000cm.​


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