A bicyclist maintains a constant velocity on the outgoing leg of a trip, zero velocity while stopped, and another constant velocity on the way back. Figure 2.22 shows the corresponding position-time graph. Using the time and position intervals indicated in the drawing, obtain the velocities for each segment of the trip.

Figure 2.22  This position-vs.-time graph consists of three straight-line segments, each corresponding to a different constant velocity.

Reasoning  The average velocity is equal to the displacement Dx divided by the elapsed time . The displacement is the final position minus the initial position, which is a positive number for segment 1 and a negative number for segment 3. Note for segment 2 that Dx=0 m, since the bicycle is at rest. The drawing shows values for Dx and Dt for each of the three segments.

Solution The average velocities for the three segments are