B3

Page 9 of The Hong Kong Polytechnic Question B3 A pendulum consists of a solid sphere with radius r = 0.2 m and mass 0.5 kg attached to a thin rod with length _ = I'm and mass 0.3 kg. The surface of the sphere is connected to the end of the rod as shown in Figure B3. Figure B3 (a) Calculate the rotational inertia of the pendulum about the pivot point, O. (6 marks) (b) Calculate the distance between the pivot point and the centre of mass of the pendulum. (6 marks) (c) Calculate the period of oscillation. (6 marks) Question B4 Two submarines A and B move towards each other in motionless water. Submarine A moves at speed VA - 30 km/h and submarine B moves at speed ve = 40 km/h. Submarine A sends out a sonar signal (sound wave in water) at 5 kHz. Sonar waves travel at 5470 km/h