For the candy bar described in Prob. 4.39, the manufacturer wishes to design the strengt...

For the candy bar described in Prob. 4.39, the manufacturer wishes to design the strength of the grooves so that:

_ Groove BC will break when a force F = 3 lb is applied in the -z direction at point D, as shown in Fig. P4.40, and

_ Groove AB will break when F = 0 and a force Q = 4 lb is applied in the -z direction at the midpoint of line segment CD (this force is not shown in Fig. P4.40).