Problem 6. When 0=20°, the 50-lb uniform block compresses the two vertical springs 4 in. If the uniform links AB and CD each weigh 10 lb, determine the magnitude of the applied couple moments M needed to maintain equilibrium when 0 = 20°. k = 2 lb/in. 1 ft B D M M A C 1 ft 2 ft k = 2 lb/in. [1ft 1 ft 4 ft