Among the elderly population, a sideway fall is a most frequent cause of hip fracture. An old man of mass 65 kg and height 1.7m was sent to Prince of Wales Hospital due to sideway fall. He slipped and fell laterally down with a straight body. Before falling, his centre of mass was 0.9 m above ground. His centre of mass was on the ground at the end of the fall. The radius of gyration about the anterior-posterior axis at his centre of mass was 0.55 m. (a) Calculate the initial potential energy before his fall. (b) Assuming his potential energy would be converted to linear kinetic energy of his centre of mass and rotational kinetic energy about his centre of mass, calculate the impact velocity v of his centre of mas right before he hit the ground. C. M. 1.7m 0.9m

Among the elderly population, a sideway fall is a most frequent cause of hip fracture. An old man of mass 65 kg and height 1.7m was sent to Prince of Wales Hospital due to sideway fall. He slipped and fell laterally down with a straight body. Before falling, his centre of mass was 0.9 m above ground. His centre of mass was on the ground at the end of the fall. The radius of gyration about the anterior-posterior axis at his centre of mass was 0.55 m. (a) Calculate the initial potential energy before his fall. (b) Assuming his potential energy would be converted to linear kinetic energy of his centre of mass and rotational kinetic energy about his centre of mass, calculate the impact velocity v of his centre of mas right before he hit the ground. C. M. 1.7m 0.9m