This can happen when you take a picture of a penny, slide it a bit (.5 cm) and then take another picture and repeat and then when all the photos are played in a fast slideshow, the penny looks like its moving.
http://en.wikipedia.org/wiki/Stop-motion#Techniques
Blurred Action: a photo where the subject is clear, but the background is not, because the subject is moving so fast.
Use the Sports action, and focus on the subject. the background should be blurred.
Panning: Where the subject is clear but background is blurred even if subject is still.
Swing the camera just as picture is taken when focus is on subject.
Blurred action is the best way because the subject is moving fast, even if it's the hardest to do.
