Q29 of 56 Page 13

A solid cuboid of iron with dimensions 53 cm × 40 cm × 15 cm is melted and recast into a cylindrical pipe. The outer and inner diameters of pipe are 8 cm and 7 cm respectively. Find the length of pipe. (CBSE 2015)

Outer and inner radius of the pipe: r’ = 8/2 = 4cm and r’’ = cm

Volume of cuboid = volume of pipe


L b h = π h[R2 – r2]




⇒ h = 2698.18cm ≈ 27m

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