A person or object moving along a path, with possible stops, can go faster or slower at different times. Assume constant speeds during one-second intervals.[more]
A common way to show this is with a time-displacement diagram.
Forward motion is shown with a line sloping up from left to right. Backward motion shows the line sloping down from left to right. If the line is flat, there is no motion. Higher speeds correspond to lines with greater slope.[less]