The support below will be used to attach a climbing rope for young children at the point of load P. It is constructed using two 2-in. by 4-in. pieces of wood braced as shown. If the allowable bending stress is 600 psi, determine the largest load P that can be applied. Also, determine the associated maximum spacing of nails, s, along the beam section AC if each nail can resist a shear force of 800 lbs. Assume the beam is pin-connected at A, B, and D. Neglect the axial force developed in the beam along DA.