The dimensions of a solid iron cuboid are 4.4 m x 2.6 m x 1.0 m

The dimensions of a solid iron cuboid are 4.4 m x 2.6 m x 1.0 m. It is melted and recast into a hollow cylindrical pipe of 30 cm inner radius and thickness 5 cm. Find the length of the pipe.

Answer

Volume of cuboid = 4.4 × 2.6 × 1 m³ 

Inner and outer radii of cylindrical pipe = 30 cm, 35 cm

$$ \text{Volume of material used} = \frac{\pi}{100^2} (35^2 - 30^2) \times h $$

$$ = \frac{π}{100^2} \times 65 \times 5h $$

$$ \frac{π}{100^2} \times 65 \times 5h = 4.4 \times 2.6 $$

$$ h = \frac{7 \times 4.4 \times 2.6 \times 100 \times 100}{22 \times 65 \times 5} $$

$$ h = 112 \; m $$