19. Velocity vs. time graphs for three objects, labeled A, B, and C, are all shown on the same axes below. All three objects start with a velocity of 12 m/s at t = 0, and end with a velocity of 38 m/s at t = 26 s. Velocity (m/s) 12 Time (s) 20 26 s A. Rank the displacements of the three objects during the entire 26 s period from largest to smallest. Explain the reasoning behind your ranking. B. Rank the acceleration of the three objects at t = 20 s from largest to smallest. Explain the reasoning behind your ranking. C. Is the acceleration of object C increasing with time, decreasing with time, or constant? Explain your reasoning. 20. Masses P and O move with the position graphs shown. Do P and O ever have the same velocity? If so, at what time or times? 1 (s) A. P and O have the same velocity at 2 s. B. P and O have the same velocity at I s and 3 s. C. P and O have the same velocity at I s, 2 s, and 3 s. D. P and O never have the same velocity. 21. Consider a kinematic equation x = (1/2) at, where a has units of acceleration, t has units of time, and x has units of distance. If t = 61.9 s, find the difference between the values of x obtained when a = 9.81 m/s' and a = 10 m/s'. A. 400 m B. 300 m C. 600 m D. 1000 m E. None of the above