Question

3.08 cubic metre of copper is drawn into a wire of radius 1.4 cm find the length of wire in km so formed

Answer 1

Pie× r square ×length = 3080000

Length = 3080000/ (3.14×1.96)

= 5.07665 Km

Answer 2

Here volume of copper given 3. 08 m³ or 3080000 cm³ (∵ 1 m³ = 1000000cm³)

Radius of wire given = 1.4 cm

Let length of wire be L

We know that when we use a quantity of any element to reshape then

volume of the shape formed = volume of the element

∴ volume of cylindrical wire = 3080000 cm³

But we know that volume of cylinder = πr²h

∴ π (1.4)²L = 3080000

(22/7)(1.4)(1.4)(L) = 3080000

$L=\frac{3080000 \times 7}{22 \times 1.4 \times 1.4}$

L = 500000 cm or 5 KM (∵ 1 cm = 100000 km)

∴ Length of wire is 5 km