If a metal pipe 10cm long has an external diameter of 12c...
If a metal pipe 10cm long has an external diameter of 12cm and a thickness of 1cm find the volume of the metal used in making the pipe
120πcm3
110πcm3
60πcm3
50πcm3
Correct answer is B
The volume of the pipe is equal to the area of the cross section and length.
let outer and inner radii be R and r respectively.
Area of the cross section = (R2 - r2)
where R = 6 and r = 6 - 1
= 5cm
Area of the cross section = (62 - 52)π = (36 - 25)πcm sq
vol. of the pipe = π (R2 - r2)L where length (L) = 10
volume = 11π x 10
= 110πcm3