Exercise: Panning with different shutter speeds

I have taken a series of photographs with shutter speeds between 1/10th of a second to 1/250th of a second of various motor cars passing on a duel carriageway.

One can see that the sharpness of the images runs from soft at low shutter speeds to sharp at high shutter speeds which is balanced against the impression of speed which is gained at slower shutter speeds and lost at higher speeds.