Practice Problems Sol3

Problem 3 Solution: The graph on the right represents the motion of an UFO.

a) In which segment is the object moving fastest? slowest? The object is moving fastest in segment C. Since the object is not moving in segment B, that could be considered the slowest or it could be argued that segment A shows the slowest motion. Physicists like to avoid the messiness of such semantics and would prefer to assign a numerical value to the velocity for each segment and not worry about which is "slowest." b) State two ways in which the motions of segments A and C are different and explain how you know. A shows motion slow and away from the origin. (small positive velocity according to the graph) B shows motion several times faster toward the origin. (large negative velocity according to the graph) c) In which segment does the object have the greatest displacement? Explain how you know. The greatest displacement occurs in segment C. Although the motion lasts slightly longer in segment A, the displacement each second (velocity) is much greater in segment C. Another way of comparing the displacement is by looking at the area between the horizontal axis and the velocity graph. These areas are calculated by velocity x time which equals displacement. Clearly, C has the greater displacement. d) Draw a corresponding position-time graph for the UFO.