In a study of head injury against the instrument panel of a car during sudden or crash stops where lap belts without shoulder straps or airbags are used, the segmented human model shown in the figure is analyzed. The hip joint O is assumed to remain fixed relative to the car, and the torso above the hip is treated as a rigid body of mass m freely pivoted at O. The center of mass of the torso is at G with the initial position of OG taken as vertical. The radius of gyration of the torso about O is ko If the car is brought to a sudden stop with a constant deceleration α, determine the velocity v relative to the car with which the model's head strikes the instrument panel. Substitute the values m = 50kg,
r = 800mm, ko = 550mm, θ = 45° and α = 10kg. and compute v.
