1- In drilling a 9 5/8" hole, the used weight is 3000 lb/inch of bit diameter. If 75% of drill collars should be in compression, find the necessary number of joints of drill collar needed. Drill...

Extracted text: 1- In drilling a 9 5/8" hole, the used weight is 3000 lb/inch of bit diameter. If 75% of drill collars should be in compression, find the necessary number of joints of drill collar needed. Drill collars used have 6 " OD and 2 ½" ID and 134 kg/Mt. nominal weight. Air is used as a drilling fluid.