Question

find length if copper wire needed to wrap thw whole surface of
a cylinder of height 18 cm and diameter 49 cm

Answer 1

Question :---- we have to find length of copper wire .

You didn't write what is the radius or diameter of copper wire ?

so, I assumed it as let radius of copper wire is 0.3cm .

$\bold{Given}\begin{cases}\sf{</strong><strong>height</strong><strong>\</strong><strong>:</strong><strong>of</strong><strong>\</strong><strong>:</strong><strong> cylinder</strong><strong>=</strong><strong>1</strong><strong>8</strong><strong>\</strong><strong>:</strong><strong>cm</strong><strong>}\\\sf{</strong><strong>Diame</strong><strong>ter</strong><strong>\</strong><strong>:</strong><strong>of</strong><strong>\</strong><strong>:</strong><strong> cylinder</strong><strong>=</strong><strong>4</strong><strong>9</strong><strong>cm</strong><strong>}\\\sf{</strong><strong>radius</strong><strong>\</strong><strong>:</strong><strong>of</strong><strong>\</strong><strong>:</strong><strong>copper</strong><strong>\</strong><strong>:</strong><strong>wire</strong><strong>=</strong><strong>0</strong><strong>.</strong><strong>3</strong><strong>cm</strong><strong>}\end{cases}$

Now ,

radius of cylinder = $\huge{\frac{</strong><strong>4</strong><strong>9</strong><strong>}{</strong><strong>2</strong><strong>}}$

Number of rotation on cylinder = $\huge{\frac{</strong><strong>1</strong><strong>8</strong><strong>}{</strong><strong>0</strong><strong>.</strong><strong>3</strong><strong>}}$ = 60

base circumference of cylinder = 2πr = 2 * 22/7 * 49/2 = 154cm

so, length of wire = 154*60 = 9240cm (Ans)

(Hope this helps)