Question

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

Answer 1

2 (pie) r

2 * pie * 24.4 = 153.30972

153.30972* 18 = 2759.57496

2759.57496/0.6 = 4599.2916

Ans = lengh of wire is 4599.29 cm

(I’m not pretty sure)

Answer 2

First find the surface area of the cylinder. Formula for the surface area of a cylinder is 2πrh. r is the radius and h is the length of the cylinder. As it is a solid cylinder the two circles at the bottom and top of the circle will also be considered. Therefore the formula for the total surface area will be 2πrh + πr^2 ( pie multiplied by the square of radius.)
Radius of the cylinder is 49÷2= 24.5cm
substituting the values into the formula:-
2×3.14×24.5×18 + 3.14×24.5×24.5=4654.265cm^2 .
=465426.5 mm^2
Therefore length required=465426.5 ÷ 6=77551.08333mm=77.51 metres