Question

A hollow cylindrical pipe is 21 dm long. Its outer and inner diameters are 10 cm and 6 cm respectively. Find the volume of the copper used in making the pipe.

Answer 1

We have,

Length of cylinder = 21 dm = 210 cm

Outer diameter = 10 cm

Outer radius, R = 10/2 = 5cm

Inner diameter = 6 cm

Inner radius, r = 6/2 = 3cm

∴ Volume of copper used in making the pipe = π (R² – r²)h

= 22/7 (5² – 3²) 210

= 22/7 (25-9) 210

= 10560 cm³