A skateboarder starts 2 m west of a marked origin line on a straight, level sidewalk. The following sequence of events occurs.
• She pushes off and moves east, speeding up uniformly for several seconds.
• She then coasts at constant speed, passes the origin line, and continues east.
• She slows uniformly to rest 3 m east of the origin line.
• After pausing for a brief moment, she walks west at a slow, nearly constant speed toward the origin line.
Ignore all vertical motion and assume her path is a straight line along the x-axis.
(a) Describe qualitatively the overall shape of the skateboarder’s position–time graph for the entire trip, beginning at the push-off and ending when she is walking back toward the origin. In your description, indicate intervals where the graph is concave up, concave down, or linear, and where its slope is positive, zero, or negative.
(b) Sketch a qualitative velocity–time graph corresponding to the motion described in part (a). Label the times when the velocity is zero and when the acceleration is zero.
(c) Explain how specific features of the velocity–time graph correspond to each stage of the skateboarder’s motion described in the stimulus.