1c. 1 m/s. The speed (magnitude of the velocity) is defined as change in displacement/change in time. In this graph that is the slope of the line, which is rise/run. Because the displacement is increasing with time (becoming more positive) we say that the velocity is in the positive x-direction. (The choice of what to call the single dimension in this one dimensional problem is completely arbitrary. We could call it x or y or z. The physics of the problem remains unchanged.)