Problem 3 (A problem from the NEXUS project) 105 2s In a study of the forces involved when motor proteins move subcellu- lar 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 Figure 2 and a graph t = 65 of the position of one of the vesicles that moved along a straight line (in a direction they call y) is shown in Figure 3. 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, Figure 2: Microscope images choose the letter for the instant of time that would represent the of a vesicle moving in a living events labeled in parts 1 through 3 below, providing your reasoning cell. The black arrow points to in each case. vesicle being tracked. 1. The instant of time at which the vesicle is moving with the highest speed. D E 2. The instant of time at which the vesicle is moving with the B slowest speed. y (um) 3. The instant of time at which the magnitude of the vesicle's acceleration is the largest. 2 For the next two questions, choose whether speed is 0.1 um/s, 1.0 um/s, or 2.0 um/s. 2 4. The instantaneous speed at instant D. t (s) 5. The average speed between f = 0 and D. Figure 3: Graph of the posi- tion of one of the vesicles that Problem 4 moved along a straight line