Question

a hollow cylindrical iron pipe is 21cm long .its outer diameter and inner diameter are 10cm and 6cm. find the volume of iron used in making pipe also find surface area of pipe?

Answer 1

radius of inner cylinder = 3 cm
radius of outer cylinder = 5cm
height of cylinder = 21 cm
volume of pipe. = πh(Rsq-rsq)
= 22÷7×21×{5×5-3×3}
= 22÷7×21×{25-9}
=22÷7×21×16
= 22×3×16
= 1056
surface area of pipe = 2πrh+2πRh
= 2× 22÷7 × 3×21+2×22÷7×5×21
= 2×22×3×3 +2×22×5×3
= 396+660
= 1056
hopefully answer right ho becoz typing me gadbad ho jati h

Answer 2

use the voulme of hollow cylinder that is pie(R square ×h)-pie(r square×h)