Question

Find the total surface of a hollow cylinder open at both ends , if the length is 12 cm , the external diameter 10 cm and thickness 2 cm .

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

The outer radius (R) = 5 cm, Thickness = 2 cm∴. Inner radius (r) = 5 cm – 2 cm = 3 cmOuter curved surface of the cylinder          = 2πrh = 2 × π × 5 × 12 = 120πcm2Inner curved surface of the cylinder 27πrh          = 2 × π × 3 × 12 = 72 π cm2.Both ends of the cylinder will be of the shape, as shown in figure (ii).∴. Area of one of end of the cylinder = πR2 – πr2          = π × 52 – π × 32 = 25π – 9π = 16π cm2.Area of both ends = (2 × 16π) cm2 = 32π cm2∴Total surface of the cylinder = External curved surface + Internal curved surf ace + 2 (Area of the base of the ring)