Question

An industrial rolling machine is made up of three identical cylinders of radius 9 cm. The ends of the rollers are surrounded by a strip of metal. Find the length of the metal strip, giving your answer correct to 1 decimal place.

Answer 1

The radius of the cylinder is = 9

The ends of the rollers are surrounded by metal strip. The metal strip goes round the circle. That is the circumference of the circle.

C = 2πr  = 2π*9 = 18π cm.

Length of metal sheet on one of the circle = 18π cm.

For the 3 rollers = 18π *3 = 54π cm.  Using π ≈ 3.14

Length = 54π ≈ 54*3.14 ≈ 169.56 cm

Therefore length for the 3 metal strips = 54π ≈ 169.56 cm