4. The heel in contact with ground provides an example of Newton's Third Law, the ground reaction force. For the picture below (LeVeau, 1992) assume the man weighs 1000N, and the angle of the foot at initial contact is 20, indicated by theta in the picture. Calculate the resultant force (0) at initial contact and the horizontal force component (X). If the step length increases the angle to 30, recalculate the X component and explain the irnpact on the horizontal component during gait? What force in nature opposes this horizontal component? What must happen to this opposition force as step length increases? Can you describe a strategy you could use to maintain safe ambulation in light of these force changes? Draw and label what yOu would expect the ground reaction force to look like? (5 pts) FIGURE 433 m--__..__.____________, Vertical (Y) and horizontal {X} components of force 0 act- ing against the ground at heei strike in walking. Relative magnitudes of the components depend on the angle of force application. which is related tat-step length. The angle made by O and Y is 9