The square-threaded boll is used to join two plates together. If the boll has a mean diame...

The square-threaded boll is used to join two plates together. If the boll has a mean diameter of d = 20 mm and a lead of I = 3 mm, determine the smallest torque M required to loosen the bolt if the tension in the bolt is T = 40 kN. The coefficient of static friction between the threads and the bolt is µs = 0.15.