4. The 30 kg pendulum has its mass centre at G and a radius of gyration about point G of kg = 300 mm. If it is released from rest when 0 = 0, determine its angular velocity at the instant 0 = 90. Spring AB has a stiffness of k = 300 N/m and is unstretched when 0 = 0. Q1: Q3: 300 mm 500 m 3 m B 3 m Q2: Q4: 45 0.35 m ial 0.1 m 600 mm -0.6 m = 200 N B k-300 N/m