Force, N 1. A force-time graph for the analysis of the walking gait of a patient is measured using a force plate. The red plot represents the vertical component or the normal force of the GRF. The blue plot is the horizontal component of the force representing friction. L and R are forces at two instants of time. Using the graph, answer the following questions. Assume that the mass of the person is 75 kg. 90H 800 I. . l': 500 ''I I1: 400 o I I 1 a I I i l I l 3 300 ' I a j I I I 200 f" : : 1 I z. ' I 108 --1'1 . . A me Time, s 08 13 12 14 16 1.3 10. 11. 12. 13. The point L is in which interval: heel strike, midstance, toeoff. From the graph read the vertical component of the force at L denoted by NL From the graph read the horizontal component of the force at L denoted by Fleon't forget the sign) Calculate the magnitude of the total GRF at L: Calculate the angle of GRF at L with respect to the positive horizontal direction. Hint: Which quadrant is the GRF vector at L? Angle the foot pushes the ground measured counterclockwise from the positive horizontal direction = The point R is in which interval: heel strike, midstance, toe-off. From the graph read the vertical component ofthe force at R denoted bv NR From the graph read the horizontal component of the force at L denoted by FR(don't forget the sign) Calculate the magnitude of the total GRF at L: Calculate the angle of GRF at L with respect to the positive horizontal direction. Hint: Which quadrant is the GRF vector at L? Angle the foot pushes the ground measured counterclockwise from the positive horizontal direction = Net force on the person at L 14. 15. 16. 17. 18. Assume that at time around 1.0 s, the L foot experiences forces and shown in the graph. At the same time, the right foot experiences the same forces at the point R. Using this assumption, calculate the net force in the vertical direction. Using Newton's second Law, calculate the vertical acceleration at t = 1.0 s using that g = 10.0 m/sz. Calculate the net force in the horizontal direction. Using Newton's second Law, calculate the vertical acceleration at t : 1.0 s using that g = 10.0 m/sz. Does this acceleration, speed up or slow down the horizontal speed is the person in the positive horizontal direction