The 8-mm-diameter A-36 steel bolt is screwed tightly into a block at A . Determine the c...

The 8-mm-diameter A-36 steel bolt is screwed tightly into a block at A . Determine the couple forces F that should be applied to the wrench so that the maximum shear stress in the bolt becomes 18 MPa. Also, compute the corresponding displacement of each force F needed to cause this stress. Assume that the wrench is rigid.