Question

A copper wire of diameter $6$ mm is evenly wrapped on the cylinder of length $18$ cm and diameter $49$ cm to cover the whole surface;

Find the length of the wire.

Answer 1

Diameter of copper wire $=6mm$
Length of cylinder $=18cm$
Since the wire is wrapped along full length,
Total revolutions $=\frac{18cm}{6\times 0.1cm}=30$
Given diameter of cylinder $=49cm$

Base circumference of cylinder:
$=2\pi r=2\pi \times \frac{49}{2}=\frac{22}{7}\times 49=154cm$

Length of wire to complete one revolution $=154cm$

Total length of wire $=154\times 30$

$=4620cm$

$=4.62$ metres.