b) Determine the minimum crack size that can be tolerated in a sheet of high-tensile yield stress of 1200 MPa and a toughness 30 kJ/m2. If the design stress safety factor is 1.5. Assume that E for the material is 210 GPA.

At a certain instant after jumping from the airplane a, a skydiver b is in the position shown and has reached a terminal (constant) speed vb = 52 m/s. the airplane has the same constant speed va = 52 m/s, and after a period of level flight is just beginning to follow the circular path shown of radius ρa = 2330 m. (a) determine the velocity and acceleration of the airplane relative to the skydiver. (b) determine the time rate of change of the speed vr of the airplane and the radius of curvature ρr of its path, both as observed by the nonrotating skydiver.