1. The problem statement, all variables and given/known data A person jumps from the roof of a house 4.5m high. When he strikes the ground below, he bends his knees so that his torso decelerates over an approximate distance of 0.70m. This the mass of his torso(excluding legs) is 45Kg,find (a) his velocity just before his feet strike the ground and (b) the average force exerted on his torso by his legs during deceleration. 2. Relevant Questions I really dont know how to start this question and all i really got was Force of gravity Fg=441N and i dont even know if its used in this question.