Here are 2 motion studies from the PA Renaissance Fair. The first uses a long lens which follows the lateral motion of the horse during exposure (1/60th"), creating a blurred background and simulated 2D motion. The other photo of the pumpkin man was forward motion created by zooming the lens back during exposure at about 1/30". Prepare to take many exposures to nail the right image. These exposures require a tripod (or at least a mono-pod) to be effective.