An F1 car speeding along a straight might allow the photographer to achieve a blurred background at 1/250 second, while the photographer might need to go as slow as 1/40 to achieve the same amount of blur for a picture of a running man.
For capturing a blurred background of an F1 car in motion, a slower shutter speed is necessary, such as 1/250 second. In contrast, for photographing a running man, a faster shutter speed is required, like 1/40 second.