1. A robot designed to walk like a human being is tested for accuracy by being programmed to walk back and forth in a horizontal line.

In a three-part test the robot walks with average velocities of $−0.5m{s}^{-1},1.5m{s}^{-1}and−1m{s}^{-1}$, in that order.

The first two parts of the robot’s walk produce an average velocity of $0.7m{s}^{-1}$ and the last part of the walk lasts 10 seconds. The final displacement of the robot is 4 m.

Plot the displacement-time graph of the robot on the axes below, labelling the coordinates of the points where the robot’s velocity changes and the coordinates of its final position.