The compressive force per area necessary to break the tibia in the lower leg is about f/a = 1.6 × 108 n/m2 . the smallest cross sectional area of the tibia, about 3.2 cm2 , is slightly above the ankle. suppose a person of mass m = 60 kg jumps to the ground from a height h0 = 2.0 m and absorbs the shock of hitting the ground by bending the knees. assume that there is constant deceleration during the collision with the ground, and that the person lowers their center of mass by an amount d = 1.0 cm from the time they hit the ground until they stop moving.