EXAMPLE: Long Exposure + Strobe

I saw this image a while ago, but I just remembered it when I was doing some work with Mr. Z on Monday. What Mr. Z and I were trying to do was combine motion with a still image, if that's how you say it. Essentially one part of the photo would be still, say a person sitting down reading a book, while people would be walking through the frame causing motion and blur. In this image, the photographer had the shutter open for 1/2 second for the waterfall to be smooth, but in order to capture the model in motion, he used a really bright flash on her. This might be a better alternative to a very long exposure where the people are required to be still. It eliminates some potential motion in the still subject.