Whirl can be defined as "move or cause to move rapidly around and around". What will you come across today that moves around rapidly? A fan? A windmill? The whirl of a skirt?
If you want to want to show the actual whirl of your subject, using a slower shutter speed will give that blurred effect making it look like it's moving. If you want to freeze motion so it looks like it's not moving, use a higher shutter speed. In this photo I used a high shutter speed to freeze the blades. It wasn't that windy on this day so it was easier to capture it due to the slow movement of the blades.
