Problem 4 (1D motion of vesicles inside cells) In a study of the forces involved when motor proteins move subcellular structures in cells, Shtridleman et al.* studied the motion of objects in living cells. In this paper, they extracted the position of a vesicle using video. Some of the frames are shown in the figure at the left below. The position of the vesicle is shown by the black arrow in these images. The vesicle moves in a straight line. The position of the vesicle along this line (designated as the y-direction) is shown at the right. t = 0s t=2s f el d 6 b y (um) t = 45 t = 6s 2 2 4 6 t(s)* Six instants of time are identified on the graph at the right and labeled by the letters A through F. Assuming that a smoothed model of the motion is appropriate for understanding the forces involved, choose the letter for the instant of time that would represent the events labeled in parts A through C below.
