It was dark, you were driving with your headlight on the highway. As you turn the corner a small kid is out on the street chasing after her ball. You slam the breaks, but you still hit her.
In which case you were driving such that your stopping distance exceeded the distance that you could see to be clear, either round the corner or beyond the reach of your headlights, so you were going too fast.
Despite the fact that people get away with flying round blind corners assuming the other side is clear all the time, you are definitely liable on the occasion that it isn't.