If the clamping force on the boards is 600 lb. determine the required magnitude of the cou...

If the clamping force on the boards is 600 lb. determine the required magnitude of the couple forces that must be applied perpendicular to the lever A B of the clamp at A and B in order to loosen the screw. The single square-threaded screw has a mean diameter of 1 in. and a lead of 0.25 in. The coefficient of static friction is us = 0.3.