Problem 3.2 If the permissible normal stress on the cross-section of member BC is 150 MPa, what is the allowable magnitude of P? Member BC has a square tubular cross-section with inner edge dimension 23mm and outer edge dimension 25mm. 4P 4P 2P 0.5 m 0.5.m -1 m- -1.5 m -1.5 m- C 30° B