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
A. 120\(\pi\)cm3 B. 110\(\pi\)cm3 C. 60\(\pi\)cm3 D. 50\(\pi\)cm3
Correct Answer: B
Explanation
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)\(\pi\) = (36 - 25)\(\pi\)cm sq vol. of the pipe = \(\pi\) (R2 - r2)L where length (L) = 10 volume = 11\(\pi\) x 10 = 110\(\pi\)cm3
