The roll radius is 50 cm and coefficient of friction is 0.2. The angle of contact is

Question

A wide strip is rolled to a final thickness of 6.35 mm with a reduction of 30 percent. The roll radius is 50 cm and coefficient of friction is 0.2. The angle of contact  is

(a) 0.5 radians                 (b) 0.0738 radians  

(c) 0.0123 radians           (d) 0.0235 radians