Every ratio (Tanθ, velocity or price), which is not changing with the passage of time or 'within time', is a constant or unchanging information, and it must be shown by a line parallel to the axis of time. In order to assert that different values of velocities were uniform within units of time it is necessary to show all those values parallel to the axis of time starting from V=0 or the initial velocity. On which axis did Newton show acceleration on a velocity vs time graph – horizontal axis or vertical axis?